All right, I'm in after I think we'll get started. Thank you everyone for joining us. I would say this morning, or midday, depend where you are and part of the country outside the country. My name is Jason's around schema University of Florida. And I will share this session today which we're really excited about to get a Grinch in the overhead athlete and musculoskeletal medicine. So, this is through the American Academy of Human R's online learning portal, this is the connect chain to overhead athlete. And it is February 12 today. I'd like to thank the American Academy of physical medicine rehabilitation the academy is really making a strong effort to provide its members with learning opportunities, particularly when a significant portion of the last two years have been virtual as we all know that we are hoping to see everyone in person. Next November. I personally know splurge disclosures from my talk. I would also like to spotlight, no pun intended, of the series and this is called the API in our spotlight series and particularly this is the heart of the connection modules. I put the website up there. I would like to thank Dr john Bianca he is the chair of the Mac for the American Academy of Human R he's leading this endeavor. This is the second of hopefully a goal of approximately two to four connection modules per year. The next one is already starting to be talked about so be on the lookout for that. And, you know, this is the world that we're in right now welcome to point point two, I thought this was pretty cool with with our speakers today. We really do have a national international player we have Dr. Craig back out in the West Coast Dr holtz is in the West Coast in Canada. Dr. Sian is in Texas myself and Dr. Bowers from the southeast. Dr. Micho is down in Puerto Rico didn't fit on this map sorry. Dr. Brothers up in the northeast so it's pretty cool when you think about it and the technology that we have. This is the line today I put this as central time the reason I did that that's based where the academy is located in Chicago, so it should be 10am right now. I will do the introductions and then a little bit of just introducing the connect chain, and how does it really pertain to the overhead athlete. Dr Bowers then go and talk about the biomechanics the baseball pitcher with this relationship with neck chain, then we'll flip it and have Dr holtz talked about from a softball perspective, particularly the windmill pitch. Then we'll make sure we bring in Dr Craig back speaking from a swimming perspective, and Dr Michelle talk on the scapula. And then, Dr. Rather we'll talk on the hip and lumbar spine and its relationship to throwing and overhead athletes. So just a brief introductions for everyone and I can spend 10 or 15 minutes with all of our expert speakers today but we're just going to do a quick slide for everybody. Dr Bowers is currently an assistant professor in orthopedics and will play of medicine at Emory in the Emory Sports Medicine Center, he is the director of the baseball medicine program and he's a team position I think for every single sports team Atlanta, but in particular the brave short tech baseball car park Skyhawks and Woodward High School Academy. And there's this Twitter below if you'd like to tweet at him. Dr holtz, she is the triumph health medical director, she's a fellow of the Royal College of Physicians and Surgeons and Kim are. He's also clinical assistant professor at the University of British Columbia in Vancouver. Prior to that, or prior to medicine she competed for Canada and the women's national softball winning silver at the 2003 Pan American Games and placing fifth in the Athens Olympics, she's an avid active researcher educator and writer and there's her Twitter handle below. Dr Craig back as a clinical professor of rehabilitation orthopedics and sports medicine, he's at the University of Washington and Seattle children's sports medicine, and he is a national team position for USA swimming. Dr. Woodward is a past president for the academy. He's also professor and chair, as well as the sports medicine fellowship director for the physical medicine rehabilitation and sports medicine department, the University of Puerto Rico School of Medicine. He's also the director of the sports injury clinic in the Center for Sports Health and Exercise Sciences for the Puerto Rico Olympic Training Center. He's an attending physician for HSS and will Cornell medicine, she's the medical director for HSS lifestyle medicine. He's the clinical medical director for the HSS osteoarthritis center and the medical director for the share savings outpatient musculoskeletal programming, and she's board certified and team our sports medicine lifestyle medicine. Hi, I'm Jason dremski I'm a clinical associate professor and director of the UF thrown clinic, as well as our medical director for the adolescent high school sports medicine outreach program here at the University of Florida and my Twitter handle is below. So, you know, to kind of start this off. You know, I think a lot of us, particularly those of us in psychiatry know what the connection is, but, you know, really what is it. How does it pertain to the overhead athlete, a lot of times we think about legs and hips and knees and ankles and how's actually pertain to the upper part of the body. So I'm going to start off with a very short case. The speakers have seen this slide, and I'm more embarrassed Dr Craig back a little bit but I was a resident in March, 2010, I did my residency at Tufts in Boston by didn't weigh rotation. I had the opportunity to rotate Dr Craig back as I wants to go do a sports medicine fellowship through a variety of contacts I got hooked up with Dr Craig back and he said come on out Seattle for a couple weeks. I'm a little bit aware I'm coming back from the Olympics so I may be a little frazzled when I come back so it was March of 2010 Vancouver Olympics had just ended with Seattle, I was a PG y three and Dr Craig got back I think he told me the day before. And I think he forgot I was rotating with them on the very first day back in clinic. So I was not possible. That's not possible. The first patient I saw happened to be a throwing athlete and shoulder pain, so I was actually pretty nervous for those of you that know me sometimes I get a little anxious and as a resident I want to impress Dr Craig back on my first day. So I thought I gave him the best, you know, efficient presentation ever and to him is probably five minutes of yada yada yada. And his first question was good job but did you actually check his hips and gluteus medius, and what I said to him was I'll back in my head it was stuff I can't say out loud right now. So this is actually something that happened that is actually kind of stuck with me that pretty much anyone who's a throwing athlete if you take care of throwers or upper extremity athletes such as swimmers cross players tennis players, etc. Really got check below the belly button so to speak. What is the connect chain so the concept was was introduced in 1875 that's the first time I can find it. If you want to have seen it, or see a publisher or in that please let me know but but Dr below said is a rigid overlapping segments that were connected via joints, and this created a system where movement at one joint produced or affected movement at another joint in the kinetic link. So there's different types of connect change and I think most of us know this unless we have a couple of our younger residents on so this will be possibly new you but they're basically an open connection the close connect chain, the open connect chain, the way to remember is that terminal segments can move freely with some characteristics, there's rotary stress pattern at a joint. For example, when you're doing a seated knee extension, the stress to the joint is in the rotation of the distal tibia distal segment, even though there's movement in other locations. There's one primary axis, the motion primarily occurs in one plane as you can see in the pictures I took from Becker Becker's manuscript. The number of simultaneously moving segments is simply limited to one. And this type are these types of exercises allow for more isolation, because less muscle co contractions you perform the movement. Close connect chain, this is when the distal segment needs an external resistance that prohibits free movement. So, you can see the pictures below the easiest example that I always tell PG y twos or medical students have been doing a squat your computer connected to the ground that's the easiest way to visualize this but a true put a close to that chain movement patterns never occur in the extremities, except in isometric exercises where no movement occurs movement will occur at multiple joints, and multiple joint axes. Simultaneous movement occurs in more than one second so this is the opposite of the open connect chain, and an increase in muscle contraction is indeed required to stabilize and control movements across the joints of the chain, like a squat. So great, you know, I just gave you an overview that he wouldn't have read off the internet right now but great so how does this actually pertains to overhead athlete, and we're throwing athlete. There's a really nice manuscript I encourage everyone to check it out, I'm actually was through the team our journal, but Dr. Chu was the lead author, and Dr. Kibler Dr job on the second and third. So really nice updated manuscript and connection or visit revisited with respect to concepts and throwing mechanics and throwing athlete. Basically the summit up is the throwing motion is a complex activity that is achieved through activation of the neck chain and this holds if you're not a thrower as well. The links are numerous throughout the body this allows for transfer of force and motion you must go back to your physics class when you were in college where you'll learn about Delta s. This requires optimal anatomy physiology mechanics, and it's involved in all phases of growing in all movements of sports whether swimming lacrosse running soccer handball, etc. If there's any breaks or deficits in the connect chain this can absolutely to injury or decrease performance. So in this came directly from Dr. Choose manuscript I thought was really nice to highlight for an understanding of the mechanics and path of mechanics seen in each phase of throwing the clinician can better evaluate and screen for potential connect athletes and overhead throwing athlete and I, again I want to make sure I'm clear on this well, this quote talks about the throwing athlete, it also came to non throwing overhead athletes such as swimmers. So obviously great this is applied all sports is Michael Phelps will probably tell you and Dr. Craig back well, well, yes, it applies if you don't throw a ball as well. Things to look at and again for the members that may be on the call today that maybe you don't see this as much or if you've been trainings or fellows on here. Starting out the ankle looking from behind you see a little overpronation of the right ankle maybe that's causing a break in the neck chain. And then doing a single leg squat, which is one of my favorite exercises to look at, in particular with females, although males as well. Is there strength in the gluteus medius is or poor proprioception is there something else going on is there neurological or neuromuscular issue going on that then impair sport performance and lead to injury. This is a more modern fashion sagittal view of someone pitching, and you can see the push off on that right leg, but you can see the, the back of the lumbar spine there's no movement or flexion. So, somehow, they're going to have to flex forward so there's going to be happy a transfer of energy, not in the most efficient way. This is a picture of a tennis or we don't have a tennis clock today. And obviously if you don't have good timing down and there's colleagues in our academy that can speak on this. You are at risk for having a lumbar injury. And obviously Dr. Holtz is going to talk about the window pitch and the connects there. Again, this is all connected these pictures alone see ankle beneath the hip lumbar spine and core and upper extremity. So how does this pertain to all thrown sports and the differences well this came from a manuscript that our colleagues at UF did. And we have five different types of motions here, even though they're all overhead. You can see, usually the baseball pitch has been sort of the baseline that folks used to compare but cricket understand the differences in cricket so if you have an opportunity to either watch or either care for cricketeers. One difference with cricketeers is in the pitching or bowling motion. You're not allowed to flex your elbow more than 15 degrees so I've actually do some research, UCL injuries or comedy john injuries are non exist, non existent and bold volleyball players, there's different types of serves you can have you can have kind of a window approach and you can have an overhead approach. Football, there's been a lot of biomechanics studies primarily led by a biomechanist, Dr. Glenn Fleissig in Birmingham, that the amount of stress on the elbow and shoulder is significantly less because of the way you end up growing the football as opposed to a baseball and javelin years javelin years is very interesting. The number of javelin years in the country and in the world is significantly less because they're just not a lot of them. If you sustain a shoulder, elbow injury due to the length of the sphere in the forces about the shoulder and elbow and the rotation the rotational work. The risk of injuries actually significantly higher than baseball players or baseball pitchers is just you don't care about as much as there aren't as many javelin years. The other thing, you know, please don't forget that the importance of the lower extremity, the trunk and scapula and Dr. Micho and Dr. Prather will be talking about this in great detail, but it's the development of optimal terminal segment acceleration and overhead motion in general. Again, failure of any links in the connect chain has implications for shoulder and elbow injury and upper extremities, as well as other locations as well. For the clinical implications look from a throwing perspective, some of our faculty members here at UF myself put this together. I think Dr. Prebeck was actually the reviewer on this or the editor. You know you have injury prevention the center but there are multiple factors that have encompass it. Yeah, you talk about how much are you throwing yeah talk about where your risk factors yeah patient centered outcome tools. Yeah, we'll get our biomechanics and how to connect chain training program you're a huge component of this. If you look at this in more detail we developed a model for injury causality and adolescent throwing athletes. And if you look at the box in the lower left hand side of your screen. These developmental risk factors, two of them that I highlighted with the arrows are strength and range of motion, and in particular quite like my shoulder and elbow there but obviously feathers once as well. When you're throwing or pitching biomechanics, these, if they are not in tune, can lead to predisposing an adolescent throwing athlete to becoming susceptible for an injury. But again, let's look at this from a non throwing perspective, look at clinical implications and swimmers, the same concept applies right here. Dr. Craig that was part of this manuscript as well. And if you look at this there's all these different factors here but I wanted to highlight to faulty mechanics can lead to fatigue can lead to injury can lead to maybe the coaches need to assist a little bit better and lack of strength and muscle imbalance again can lead to the same concerns. So what's important you actually understand the biomechanics graph, just because you like swimming, or just because you like softball doesn't make you an expert in it, you have to understand what your athletes are going through, and what they're doing, and you have to understand biomechanics, do you have to be a PhD like Dr. Bowers, no, you don't. It's helpful. But if you do have to learn more about it you're going to have to read, not just the clinical manuscripts, you're going to have to read the biomechanical manuscripts as well. So for example in this swimming cartoon, really nice from Dr. Casa Guerra, is that you have to know what muscles are supposed to be active in different phases of your swimming stroke. From an injury prevention standpoint because honestly if you want to study this, you're going to have to have access to athletes whether professional Olympic Paralympic collegiate high school and younger. And I can tell you from experience I think every speaker on here can tell you from experience that if you don't propose this to the coaches and the athletes that your research can lead to injury prevention improve performance, they don't care. So this is really important from two perspectives. Injury prevention, something called the Y balance test, a decreased score on the Y balance test can actually lead to or has been shown to lead to an increased likelihood of possible UCL injuries in the elbow. What about scapular dysfunction? Well we know that scapular dysfunction is 43% more likely to develop shoulder pain in athletes than without scapular dysfunction. Injury prevention again, limitation in hip range of motion. This can affect upper extremity loading during throwing motion and also negatively impact performance and elevate injury risk. And actually healthy and uninjured tennis players, this is actually a really cool study, failed one leg stability about half the time indicating hip weakness. So you can imagine if you could just test someone, that very first slide that I showed when I was a resident, and check their gluteus medius on a simple pre-participation screen examination, or during a physical examination because they may be injured, or the athletic trainer is checking them out, you'll be able to detect something much sooner than when they develop an injury. And with that, that's just a little flavor of everything that our experts are going to talk about. So again, these times are in central time zone. So, we're going to have Dr. Bowers up first, then Dr. Holtz, Dr. Krabeck, Dr. Micheo and Prather and then I blocked off 20 minutes for additional Q&A. I will make an effort to check the chat function as we go so that we can try to answer a few questions between each other, we certainly will. And with that, I'm going to unshare my talk and let Dr. Bowers take over. Thanks, giving me some extra time. That is a dangerous proposition. Okay. Sharing this all good? Yeah, looks good. Good. So let me see if I can. Come back, give me one second. Okay. So I'll go ahead and get started with this and I think probably what you'll, you'll end up hearing across the course of the, you know, the session this morning is a lot of the same things from all of us as far as the kinetic chain goes. So certainly some of the things that Dr. Zaremski already touched on, I'm going to touch on in my talk as it specifically pertains to the pitcher. So I'm also standing up for this and I may demonstrate some things or try to my best as we're doing this so if you see me moving around a lot, that's the reason why. But at any rate, so we're going to talk about the kinetic chain and the biomechanics of the baseball pitcher. I'm Robbie Bowers. I'm the director of the Amory Sports Medicine Center in Atlanta, and the director of our baseball medicine program we started a couple years ago as well as take care of some of the baseball teams here in town including the Braves and Georgia Tech's baseball team. So I'm excited for college baseball season to get started next weekend from a Georgia Tech standpoint. A couple of slides that I do have in this talk come from Dr. Zaremski and Dr. Holtz, so I assure you if there are, if you see any similarities between my talk and Dr. Holtz's talk, I ripped her off, she did not rip me off. So just, I'll throw that out there to begin with. Shameless plug, this is just the site for our baseball medicine program has resources on there if you're interested, you can go to the site and see if there's anything that may help you out from a baseball medicine standpoint. Another shameless plug Dr. Zaremski and I recently just, this was just published in the final formatted version just came out yesterday so you can find that through the PM&R Purple Journal, our review on upper extremity peripheral nerve injuries and throwing athletes, and I bring this up because a breakdown in the kinetic chain frequently will lead to these peripheral nerve injuries and throwing athletes and so what we're talking about today just pertain to to these peripheral nerve injuries that we wrote about in this review. So, if anyone's seen some of my baseball talks before you know a lot of times I'll lead with this question. This is the most common injury in professional baseball and frequently we think of baseball players as upper extremity athletes. However, the, the most common injury in baseball is actually a hamstring strain so it's just an, you know, an interesting thing to think about that even in our so called upper extremity sports, and we'll talk about this today. We want to focus on lower extremity and the trunk as well. So this is a good definition of the kinetic chain and athletic performance in general from from this paper, just last year. It says an effective athletic chain is characterized by three components so number one is going to be your optimized anatomy so you work on the appropriate strength and flexibility and power generation and the appropriate body segments, and then efficient task specific motor patterns for muscle activation so an optimized biomechanics from a baseball standpoint so picture biomechanics and then number three sequential generation of forces that are going to be appropriately distributed across those motions of the baseball pitch that are going to end up with your desired athletic function. And so I think this is a good explanation of the kinetic chain just athletic performance in general that can go across for whether it's baseball or softball or volleyball or swimming or tennis any of these overhead sports. So the kinetic chain and baseball pitchers specifically, and the kinetic chain as we touched on begins at the legs and the hips which transmits energy to the trunk to the shoulder to the elbow and eventually to the hands to impart that power on the ball relative weight and any deficiencies in the kinetic chain are going to result in more stress on the distal segment so the upper extremity, your shoulder and your elbow. We need to decrease performance and increase risk of injury. So you just have to understand the importance of training the whole body so from the hips to the trunk to the scapula, not just your arm care program from from a baseball standpoint so you're certainly going to focus on your arm care program for pitchers. But if you have weak hips or weak core or scapular dyskinesis, you're going to be shot and it's not going to matter what you what kind of arm care program, you're doing. So this is kind of wordy but kinetic chain. The sequence of body movements started so for specifically with baseball with lifting that that lead foot in the wind up phase, you're going to progress to a link motion of the hips and trunk that culminates with the ballistic motion of the upper extremity to propel the ball. And so the lower extremity of the trunk really what it was going to generate that force that you're then going to transmit to the arm and you're going to use the scapula, as the, and you'll hear I know you'll hear Dr Holtz said the same thing and I'm going to say it, the scapula is the force funnel that's going to take that energy from the lower body through the scapula and impart it onto the upper extremity. So the lifting motion should not just be considered an upper extremity action, it's the integrated motion of the entire body that just culminates with the rapid motion of the upper extremity and optimist optimization of mechanics and the kinetic transfer of energy from the legs in the core to the throwing arm, and it's this optimization that's going to prevent injury by reducing forces on the throwing shoulder and throwing elbow. So look here at the phases of the pitching motion intricately coupled for the efficient generation and transfer of energy so the first phase is going to be your windup phase. Second phase is stride, third phase is arm cocking, followed by arm acceleration, arm deceleration and follow through. And so you'll see down here, kind of what, what, what are the endpoints of each of these phases and so the windup phase is going to be that balance point where you're on your back leg and you kind of have maximum knee height. The, as far as the stride phase, the endpoint of that is going to be your foot contact for the cocking phase the end phase there is going to be maximum shoulder external range of motion. For an arm acceleration phase the endpoint is going to be ball release for the deceleration phase your endpoint is going to be the maximum internal rotation of the shoulder. And then for follow through is going to be when the pitchers in that fielding position which, you know, frequently at the end of the motion you'll see pictures falling off to the side one way or the other and won't be in a perfect building motion. That's going to be the end of our follow through phase. We can see this here a little bit more fluid they just added a couple more pictures and in this in this here so you see the windup phase where you have the, the maximum knee height. Go down to foot contact and in the stride phase maximum external rotation of the shoulder and in the cocking phase. Ball release and in the acceleration phase, maximum internal rotation shoulder in the, the deceleration phase, and then the pitcher at the end and his so called fielding position in a follow through fits. So, what are we doing through the phases of pitching, you're creating energy in the lower body and core, and you're transferring that to the arm through the scapula for ball release. So the windup is going to position your body in preparation for force generation, your stride is going to initiate velocity through linear forward movement that places the arm in the cocking position the pelvis it's going to rotate forward toward towards home, generating more power in the cocking phase, you're going to see many of the shoulder and elbow injuries are going to be encountered in this cocking phase is where you get a lot of rotational show to shoulder torque, and a lot of elbow elbow valve this their energy is transferred here from the lower body to the upper body to the scapula as you as you're rotating towards the batter. And this is going to begin when that lead foot hits the ground. In the acceleration phase you're transferring all of that energy from the body on to the arm and on to the baseball, you're getting explosive power through the shoulder internal rotators with with powerful elbow extension and wrist flexion deceleration the baseballs released your internal rotators of the shoulder slowed that rotator cuff is going to resist the distractive momentum of the arm, and then follow through that motions complete in the bodies in the fielding position. So key points here in the phases and then I'll, I'll let that go so the wind up in stride position, the lower extremity and trunk for effective performance through the kinetic chain, the legs in the trunk again are the main force generators with the that's going to facilitate energy transfer from the legs in the trunk to the upper extremity you hear me say that more times across this talk as we go along, is power from the legs in the trunk that powers is funneled through the scapula to the upper extremity. So scapular dysfunction is going to prohibit optimum energy transfer scapular dysfunction equals more stress on the shoulder and elbow, which equals more of an injury risk so again, with without focusing on the hips and the trunk and the scapula. I think you're you're missing the boat when it comes to throwing and specifically baseball pitching by mechanics. So just a quick mechanics just checklist that will go through here so we had a video of the picture over here. And then, this is, this is from Dr. Holt she put this mechanics checklist together, I lifted it off of her and so this is credit to her for these this checklist. So we'll start here in the wind up phase just as we were talking about. And as we pause here, and I have that maximum knee height with the pitcher balanced on his back leg. Then, in the stride phase, we're going to begin to see his foot forward in the stride phase here, which is then going to take us to front foot contact. And at front foot contact you want that want them to be slightly towards that front foot in a right-handed pitcher is going to land slightly towards third base with a slightly inward angle of that landing foot that shoulder ideally you'd want around 90 degrees of abduction which we're close to here he's a little bit dropped down in that shoulder at around 60 degrees of external rotation so now we're going to really go into that cocking phase and we'll pause it as he gets to maximum external rotation which is about right here you'll see that pelvis that pelvis and trunk have kind of rotated the pelvis rotates first the trunk rotates after that and that shoulder is going to be maximum external rotation around 180 degrees and the acceleration phase will end at ball release right about here you'll see that elbow is going to extend forcefully the shoulder is forcefully internally rotated and that front knee is going to extend so you'll see it when that front foot lands you're going to have some knee flexion and then as you release the ball you get a lot of power generated through extending that front knee so release the ball here put that shoulder around again and in 90 degrees of abduction you're going to see that lateral trunk tilt away from the throwing arm which you see here from the pitcher as you really pull that lead arm through and then you're going to see in the deceleration phase that trunk is going to flex forward and the arm is going to cross in front of the body so that's just a mechanics checklist that we'll look at as we're going through and assessing pitching motion so really what i want to focus on here are some of these common points uh the breakdown of the kinetic chain this is from a review in sports health back in 2010 and so if you have a premature forward motion during the wind-up and stride phase and that premature forward motion could either be that you just have poor balance and you're and you're falling forward or it could be due to the fact that you have weak glutes and when you come off onto that balanced leg you don't have the glute strength to to balance you and you're going to kind of tilt forward and so if you have premature forward motion that arm is going to lag behind the body and decouple the kinetic chain and so that's one place where you can you can get some kinetic chain breakdown now we're going to look at the the landing foot and so we'll see that here so over here we see that landing foot is landing in a closed position and the foot here see the landing foot is is landing in an open position so if you land in a closed position that's going to decrease your ability to rotate the pelvis and the trunk you've got to throw across your body and you're going to have decreased force generation through the kinetic chain if the stride foot lands in the open position we're back to what we talked about before with with premature forward motion is that's going to decouple the kinetic chain your arms going to lag behind the body and you're going to have to generate more force through the shoulder and the elbow which will increase entry risk so if we come down here and we we look at increased lead knee flexion at ball release so as we talked about before at ball release you can land with your knee inflection but you really want to forcefully extend that knee as you're moving towards ball release to generate power so if you have increased knee flexion at ball release it means you're not generating that force and so again that's just less force generated by the torso um that doesn't allow you to impart that that force onto the ball if you have diminished external rotation at late cocking again the acceleration forces that act on the ball is just going to be over a shorter distance so you're not going to impart that force on the ball and then again so still you'll hear it i think in a number of our talks today is scapular dyskinesis and so with scapular dyskinesis you're just you're not going to have optimum force transfer from the lower body and trunk onto the arm which is is going to lead to increased injury risk decreased force imparted onto the ball and also see with scapular dyskinesis and throwers who can lead to subchromium pinchment as well this here are just a couple cartoons from the chalmers paper in 2017 in sports health this is just you can see here the arm kind of lagging behind the body and in the second picture uh picture here so you can imagine if you were to land with your front foot kind of in an open position that arm lags behind the body a bit and then here in the second picture the three kinetic factors shown to correlate with injury which is going to be elbow valgus torque shoulder external rotation torque pitch velocity which we won't you know it's kind of beyond the scope of this talk the effects of velocity and and injury risk but so we'll focus on valgus torque and shoulder external torque and you have these increased forces with a kinetic chain that is not optimized so if you're not transmitting that power from the lower extremity through the scapula to the arm it means that you're putting more force through the elbow and through the shoulder so you're going to have increased rotational torque on the shoulder increased valgus stress on the elbow which is going to increase your injury risk so from the get-go you need to have strong glutes and good balance so don't let chubbs and patty gilmore throw you off here but he is right when he says it's all on the hips so to begin with so imagine this leg this front leg coming up there's a right-handed pitcher this front leg is is coming up here and so you're bringing that leg up into the balance point and so we see here in this first picture your hips stay level because you have a strong gluteus medius that can fire and keep your pelvis level if you have a weak gluteus medius so when you bring that lead knee up if you have a weak glute med that's going to cause you to tilt forward and your kinetic chain is you know is essentially screwed from the echo and so it doesn't matter again what's going on with the upper body if you have weak glutes especially for a baseball pitcher you're doomed from the start if you have weak glutes and so that's the number one thing you you do want to look at because before you get to anything else before you get to scapula before you get to the arm if you have weak glutes then then that's going to be an increased injury risk for this picture. So this is a slide I got from from Dr. Drzymski I added a couple things to it so the glutes and the scapula musculature I think we really say two things you know look at the glutes and look at the scapula pelvic and scapular stabilizers as I've said and you've kind of gleaned to this point are very important in baseball pitching so if you look specifically at this paper from Gretchen Oliver who does a lot of great work baseball softball medicine she's at at Auburn in Alabama where uh where I did my PhD so the most important muscles here are going to be gluteus medius at the hips and your serratus anterior and lower traps at the um at the scapula and so if we really want to look at it it's for injury prevention in baseball pitchers you're not just doing your arm care program you're also focusing on the lumbopelvic hip and scapular muscle strengthening as well as a coordinated strengthening of the pelvic and scapular stabilizers and they point this out in the paper from Dr. Oliver here. So again don't forget to look at the hips so this is another slide I lifted off of of Dr. Drzymski and it just shows us that you know hip weakness and decreases in hip flexibility specifically rotational flexibility are associated with increased risk of injury at the shoulder and the elbow and we'll see this here and then we know from from studies like this right here that from Dr. Farmer and and some of Dr. Drzymski's other colleagues at the University of Florida that that changes in hip range of motion and strength do occur across the season in baseball players and you're going to get decreased rotational range of motion increased hip weakness which again is going to be associated with increased entry risk so these are things that we want to look at across the course of the season some of our baseball players so changes in hip range of motion occur over the course of the season this is associated uh or you know hip rotational range of motion is associated with shoulder injury so changes in hip range of motion lead to an increase in shoulder torque while throwing which leads to increased injury risk again more looking at the hips here as well so hip injury is associated with UCL injury and so players that have previous hip injuries if you look at the data in major league baseball players also a higher risk of having subsequent UCL injuries we also see here players diagnosed with ulnar collateral ligament tears demonstrate decreased balance a lot of what plays a role in that balance is the gluteus medius so what the balance test that they use here is that y balance test that Dr. Zarymski talked about the gluteus medius plays a large role there so that decreased balance has a lot to do with the gluteus medius and so hip weakness decreased hip range of motion rotational range of motions also associated with UCL injury so in baseball players hip weakness decreased hip rotational range of motion increase with UCL injuries also associated with specifically slap tears at the shoulder so the hips take home hip weakness or tightness decouples the kinetic chain and leads to decreased performance and increased upper extremity injury risk and this is going to be decreased hip rotational flexibility hip abduction weakness and so that specifically the gluteus medius is going to give you that positive Trendelenburg that that you'll see if you bring them up on the to one leg that that gluteus medius can't fire and keep the pelvis stable and you're going to dip down and then also you have valgus knee collapse on a one-legged squat and so here's your one-legged squat here and when instead of keeping the knee over the toe as they come into that one-legged squat you're going to get this valgus collapse and that also is associated with decreased um hip strength or or increased hip weakness and so this paper from Burkhart 2000 shows us as I just mentioned previously the decreased hip rotation flexibility and hip abduction weakness is seen in 49 percent of athletes with arthroscopy proven slap tears so hip weakness decreased hip rotational range of motion associated with slap tears in the shoulder as well as UCL injuries at the elbow so I don't want to step on Dr. Macheo's toes too much in talking about uh the scapula here but again as I mentioned the scapula is very important looking for scapular dyskinesis and scapular dysfunction and you're throwing athletes when they come into the office so have them take their shirt off anything from Dr. Kibler I'm sure that that most of us know anything from Dr. Kibler is going to be an outstanding resource when it comes to scapular dyskinesis and overhead athletes now as I mentioned before I know Dr. Holtz will scapula is a force funnel from the lower extremity in the trunk into the upper extremity and so if you have scapular dyskinesis and scapular dysfunction you're not going to be able to effectively um funnel that force from from the proximal aspects to the more distal aspects and so when you're evaluating the scapula so you're bringing them to forward flexion they'll do that several times and you'll look for a prominence of this medial border here in the scapula and then also as they come into the abduction you'll look for that dyskinesis and abnormal motion compared to the non-throwing side sometimes if you're palpating you'll actually feel a clunk in that scapula there so you're going to look for a prominence of that medial border as well as the motion of the scapula from one side compared to the other you can both look at that motion and you can feel the motion as well so the kinetic chain and prevention specifically for the core and the hips and the lower extremity you want to test hip abduction and glute strength those dynamic tests are going to include a single leg a squat and the y balance test that Dr. Zeromski had mentioned the y balance test is a little difficult to do in the office because you have to have some equipment for it so my go-to in the office quickly is a single leg squat you want to look at your hip and trunk range of motion to identify any asymmetry and internal external rotation because as mentioned these changes in hip range of motion are associated with shoulder injury and overhead athletes elbow injury as well and a stable base can efficiently transfer that energy from the lower body to the upper body through the scapula and control the forces that develop on the shoulder and the elbow so a case in point here is Mark Fidrich actually put this in last night because I was watching the MLB presents on Mark Fidrich and also known as the bird and he was kind of a flash in the pan back in the mid to late 70s and you know he came on the scene red hot as a 21 year old for the Tigers and just came out guns blazing and did amazing in 1976 and then they get into 1977 in the beginning of the season he injured his knee and the Tigers realized that Fidrich was was their meal ticket and so they rushed him back from this knee injury he came back two months after having uh after having knee surgery which was way too soon probably if you had this happen today he may have been out the entire season so they bring him back and his first two starts were great he did very well but then he started to break down and the reason was they rushed him back he didn't have that stable base in his lower extremity his mechanics were changed he did not have an an optimum kinetic chain and he actually ended up tearing his rotator cuff and we know that in in a pitcher a rotator cup tear is disastrous and so from you know he kind of bounced around between the minors and the pros through like the 1982 season but he was never the same as he was in 76 and this was all because a lower extremity injury rushing him back affected his mechanics um did not have an optimum kinetic chain and he tore up his rotator cuff and ended his career so just a case in point uh kind of a real world situation for this another uh I lifted this off Dr. Dremski too so hopefully at least half of my talk is not just stolen slides from him and Dr. Holtz um so when does this injury cycle start and we see it in the youth and the pre-high school kids and the reason for pointing this out is that we really want to focus on mechanics in our younger athletes and our younger throwing athletes because if they don't have optimum or good mechanics once they get to the high school age when their power really increases then they're going to be at a significantly increased risk of injury so as I just said if good mechanics are not taught by high school when power begins to increase there's an increased risk of injuring the shoulder and the elbow so again really need to focus on the kinetic chain and proper mechanics in our younger pitchers so as to decrease their injury risk as they get older and we see this in papers like this the effect of pitching biomechanics on upper extremity in youth and adolescent baseball pitchers and so their conclusion here was youth pitchers with better pitching mechanics generate lower humeral internal rotation torque lower elbow valgus load and more efficiency than do those with improper mechanics and proper mechanic pitching mechanics can help to prevent shoulder and elbow injuries in youth pitchers so you know we see different studies like this and it just you know it tells us we need to we may think we're being a bit premature and some of our younger athletes and really focusing on mechanics but those are the things that we need to look at we need to focus on mechanics and then you know we get into looking at at location before we start trying to teach our young kids to throw curve balls and whatnot there how do we assess these mechanics we don't have a really great easy way to assess mechanics and i'll wrap up here quickly so we have things like the pulse from driveline which used to be the modus sleeve also have marker based which is kind of the gold standard you go to a biomechanics lab that they do the motion capture with marker based things and we see that here but a lot of people don't have access to either something like the pulse or a biomechanics lab and so what we've set out to do here at emory is to develop an evidence-based pitch efficiency rating system that's easily accessible for coaches or even physicians or physical therapists or athletic trainers or for baseball players we want to create a standardized assessment tool and a reliable method to systematically assess pitching mechanics that doesn't require you to to use any of these wearables or also to have to go to a biomechanics lab last year we already established the inter and intra-rater reliability for the pitch efficiency rating we put together so that's kind of step one it's a point-based systematic tool it's easy to use easy to teach easily accessible it's user-friendly with little to no cost and then now we're kind of going into a more longitudinal study where we're going to look at our pitch efficiency rating and how it relates to injury over the course of the season and some of our adolescent baseball players and this is what we're looking at we provide kind of a table or a reference table that people can look at to do their scoring for poor good or excellent mechanics and then they go in and they put in their score here and it comes out to a total and so their total score we can we can look at and see if that relates to injury but it also lets you you know look at the entire pitching motion and hone in on those areas where a pitcher could be poor related to other areas of the motion and so results moving forward like I said it is reliable we had excellent to good intra and inter-related reliability now we're going to see how it correlates with injury moving forward so in the next frontier in in looking at the kinetic chain specifically in baseball players it's just it's going to be looking at energy flow and so Gretchen Oliver who I mentioned previously is uh is doing a lot of work here starting to get in to do a lot of work so we're not just looking at the mechanics from a kinetic chain standpoint actually physically measuring the energy as it flows through the body from the lower extremity through the trunk and the scapula to the arm and so this physical matter of measure of energy is just another way that we can look at the kinetic chain to see is this energy flowing efficiently through the body or is it hitting stops through the chain and so both measuring the energy and looking at the mechanics could be that we the way that we look at the kinetic chain moving forward so energy flow again I had this picture earlier and this is just you know think of the arrows as how energy is flowing through the body from the lower extremity up to through the trunk to the arm and that's what you're measuring with energy flow is the is the you know the physical flow of energy as it as it goes through the body so remember as I'm wrapping up here more than anything as our good friend Chubbs says it's all in the hips and if you don't have that proper hip strength in the gluteus medius especially with a baseball pitcher you're doomed uh doomed from the get-go so thanks I want a couple minutes over but uh I appreciate it and thanks for having me today that was uh that was fantastic thanks Robbie um we have one question before going to Dr. Holtz um it's in the chat but I'll just read it um Dr. Bowers is there a kid-friendly education tool on proper biomechanics that can help them learn how to incorporate segmental movements into their throwing motion either for the kid or for parents or their providers yeah and and I'll let you kind of weigh in on this as well um and I think that's that's kind of what we're trying to develop with our our pitching efficiency rating here is to to have you know a quick and easy resource that people can go to I still point most of you know most of my youth athletes and their parents to the Pitch Smart website um they have all sorts of resources through there um I don't know if there's something else that that you use I mean honestly a lot of time what I do is instead of trying to get deep in the weeds with anything because then we're just gonna especially if we're just talking to the parents and or their pre-high school so athlete trainers isn't really an issue uh or an or an option at that point and I say look everyone's got an iPhone or an Android or some form of device that can capture video just tape your son or daughter show it to me and we go through you know we we can talk about the amount of torque or rotation or you know three degrees I try to keep it simple I usually pick two or three things and say like look get the elbow up or you're stepping in the bucket you know things that we probably all went through when we were younger in whatever sport we played but we usually start with that component I'm sure the other speakers on here will probably have similar stories saying let's get your elbow up and let's stop closing your hips off just do those two things and come back to me in a month so as opposed to what what you guys are doing at Emory and um you know in a few other places too and I know one of your partners did this with tennis Dr. John the family medicine to try to have something honestly where you don't need a lot of money or if there's a socio-economically underserved area to to do what you know what you guys are developing I think it would be awesome to be able to bring to the masses so yeah yeah exactly that's that's what we're trying to to develop is is like you said everyone now has an iPhone that they can take a video so they take you know you go you take a picture behind your son or daughter you take a picture to decide at 90 degrees you you can look at the table we provide and you score it and it's just a simple quick and easy thing to do it allows you to you know to easily you don't have to have a lot of training for it allows you to easily assess and see where kind of the deficiencies in the motion are and and that's what what we're trying to develop here and so I think that's a little bit of a gap of of something we have that's kind of systematic um and that's we're trying to develop so um but yeah so we're we're trying to do that essentially exactly what you're doing just by having to show you the the motion on their video and then again and I see uh Dr. Holtz put put some of the links here in the chat as well just some links to the MLB pitch smart website and they're some of the things that they have on biomechanics there we'll have one more question and then we'll go on Dr. Holtz, Dr. Tomsky I think your hand is up yeah thank you very much for uh that fabulous uh presentation uh there are uh we've been looking at the muscles we've been looking at the trunk rather non-specifically and uh Ernie Johnson talked about the alleged common injury of hamstring injury he looked at Ohio State football players and hamstrings and he found 90 percent of them were radiculopathy and over the last nearly 40 years in practice that's what I've found when we look at the weakness at those muscles that are served by L5 predominantly we're focusing in this kinetic chain we're not talking about side bend rotation and we're not talking about the rib cage and uh as an MD physiatrist who's been luckily trained osteopathically I think I don't hear anybody in the sports medicine world adequately addressing that so that's my comment. I will briefly say not to give anything away I think I'd like to hear when Dr. Prather talks since she is the expert not only today but one of the experts I think in the country in hips and lumbar spine um but I think some of some of that will be addressed I don't know if Dr. Bowers or anyone else on right now wanted to comment or say just anything I and I agree with what you're saying Dr. Tomsky I've seen that a couple times too but I don't have the experience you do at this point but I would not disagree with what you're saying but Robbie I don't know if you had anything else you want to add? Yeah my initial was let's wait and see what Dr. Prather has to say and then and then if there's anything left over go from there. All right without further ado Dr. Holtz. Okay let me just share my screen here. Okay I'm gonna assume you can see my slides and all as well unless someone pipes up. That's great. Great so thanks for inviting me to talk about the softball windmill pitch and how it differs from baseball. I'm sure you'll realize pretty soon that there's a common theme amongst all of us that we're not actually that different um just a little bit about me so I I've uh I'm approaching this talk more from a coach perspective. I've coached softball um longer than I've been probably interested in medicine at least since high school and had the privilege of playing at a high level and so I've been coaching through medical school and residency and been able to work with kids as my understanding of the kinetic chain has improved. And you know now I'm really in my dream job well maybe Robbie has my dream job but in my dream job of being able to understand softball from a medical perspective as well as a coach perspective and giving talks like this is just icing on the cake so thanks for having me. I will advance this way. I have nothing to disclose. So just a quick summary about kind of where we're going to go in the next 20 minutes or so. Give you a few quick softball facts if you're not a softball nerd or new to the sport. Describe the phases of the windmill pitch. Review the importance of the kinetic chain in windmill pitching and hopefully break down um you know how that force funnel works at moving from the trunk through the scapula and then I have some video examples of proper kinetic chain use and others that you know may need some work and hope hopefully I can equip you with some kind of coaching minded tools to use in the office and then I'm going to discuss some tests we use in the office and review a little bit of the work I did as a fellow with UBC baseball team and how we approached evaluating the kinetic chain in pitchers. So there are over two million fast pitch softball players in the U.S. It's a popular sport really popular around May when the Women's College World Series is on. Softball, a softball as you know is larger and weighs a bit more than a baseball and there's some thought that perhaps that can influence injury risk at the shoulder. NCAA surveillance data over the last 20 years as well as data from the Olympic Games shows kind of game and even practice injury rates to be quite low but when you really dig into the pitching position up to 70 percent of college pitchers report pain. This is a picture of the Hall of Fame Stadium of the at the Women's College World Series and it's really been cool to see how it's grown over the years. I've added upper decks and grandstands in the outfield. So I thought it would be important to include this paper which looked at medical costs so this was you know five or six years ago now but looked at medical costs in the Big Ten over five years and they followed 36 teams and actually the biggest spenders were football teams and women's teams. Actually the biggest spenders were football, wrestling and softball like arm pain is a major issue in softball, arm and back pain. And so if you find yourself caring for softball athletes just remember the three S's. Most injuries occur at the start of the season. Most injuries are strain injuries at the shoulder and low back strains kind of occur second and when I played college softball I suffered from both. I think the low back strain was me carrying my books around but I certainly had shoulder pain throughout most of my career. I have another thought on that but we'll wait till the end when we're talking about injury prevention. So like baseball we can divide the phases of the windmill softball pitch according to what's happening biomechanically. For some reason we had put the softball pitching motion on an analog clock and now when I try and explain an analog clock to young kids they look at me like I'm so old so I've just stopped and applied baseball terms to the softball pitching motion instead. So there's a wind up, a stride, this kind of preparation phase just prior to front foot contact, a ball acceleration from front foot contact to ball release and then follow through. Now we were prepping for this lecture series last week and having a mechanics discussion and also a coaching discussion. And so this is for Dr. Zaremski's benefit because Alabama and my good friend, Pat Murphy is the head coach at Alabama, usually comes down and beats the pants off UF. So I thought I'd break down for him why Montana Fouts is so effective for Alabama. So this is, I'm just gonna play maybe half of it or so. A clip from Montana Fouts' perfect game at the World Series against UCLA. I also thought I'd share the energy. Yeah, when it's called World Series, it's really a cool event. I never had the chance to go. So you can see Montana's throwing in the early serving. But if you watch her back foot, and kind of the glute of the back leg, you can see that she is balanced on her back leg throughout her whole switching motion. So I thought I'd walk you through why Montana Fouts is so effective in my opinion. So she's tall, she's over six feet. So she's got really long levers. And as she strides off the mound, her hips open to the catcher. But just before contact, you can see she's already activated the lower half of her body and started engaging the back hip here in the form of internal rotation. When I played on the national team, Laurie Sippel, who's one of the associate coaches at Nebraska and probably one of the best Canadian pitchers, maybe behind Danielle Laurie for Canada. She used to always say to me, think about driving your back knee down towards your front foot or drive your knee to the catcher. And so you can really see Montana's doing a good job of that. And you would imagine if she's just balancing through this back leg, that her back glute is firing like crazy to be able to keep her pelvis up and lean kind of back towards the throwing arm. So she started to engage the kinetic chain here. You can see now after kind of starting to have landed, her hips start rotating towards the catcher, but her shoulders are still open. So now she's trying to transfer the force she's generated from her back leg through her trunk up towards the scapula here. Now, when she lands her arms at about 120 to 130 degrees of abduction, her arm was up much higher than she'd have this position of kind of scapular elevation on her thorax. And that would really impede the force transfer through the ball here. So we'll talk about some examples where that, in some of my pictures where this was the case, but for her, her scapula is kind of retracted on the rib cage and ready to send force through the ball here. And then lastly, in softball, the pitching motion is finished with this forceful kind of, you can see she's externally rotated of her arm here, forceful internal rotation motion, and then the wrist snaps over. So like Robbie, I thought I'd walk you through the pitching motion kind of phase by phase. This is a video of me throwing for the Mass General Biomechanics Lab. They were running a softball study. They published, Donna Scarborough published a few papers. They're looking at range of motion and joints and then some biomechanics parameters. So I'll just run it through right now. These are the first three phases of the pitching motion. So this is the windup and the windup ends when max pre-motion is achieved. So the arm goes completely back. Now, pitcher's arms don't have to swing back. That's just really the convention here in kind of North America, but Australia and Japan, they like to keep the ball, you know, hands together and kind of do this backwards pre-motion with the hands together. It doesn't matter in my mind that style points, not interfering with the kinetic chain. And then when we talk about legs in baseball or softball, we're talking about the stride leg and the non-stride leg or the stride leg and the back leg, you'll often hear people say. So the front leg goes up and forward. And then just prior, oops, we'll advance it here. Just prior to front foot contact, you can see that the foot is turned inward. It's actually slightly towards first base. And depending on what paper you read, this is Dr. Werner's biomechanics assessment of the 2000 Olympic pitchers. They were, and so kind of, they had reported when front foot contact occurs, that shoulder is abducted to about 150 degrees. Mine's probably close to that here, but subsequent biomechanics analysis have suggested it depends on what type of pitch you're throwing. And so anywhere from kind of 120 to 150 is probably acceptable. And the shoulder is externally rotated. And looking at this from the front, this is one of the first few phases. So wind up, stride, front foot contact. You can see here that my pelvis starts rotating. So my hips are rotating, but my shoulder has not, my shoulder upper trunk hasn't rotated yet. So in this preparation phase, pelvis rotation is followed by upper trunk rotation. The shoulder is still externally rotated and the elbow, you can't see it cause it's a little bit behind me, but it's extended. There's about 10 degrees of flexion or so. And then the elbow extends followed by forceful internal rotation. You can see that here. The stride leg remains flexed. So you don't want it to be straight or you're kind of like run over your front side. And you need to be able to kind of stop your forward force linear translation with a bent but firm front leg. There is some lateral trunk tilt towards the throwing shoulder, which I'll highlight in a slide coming up here. And then the arm crosses in front of the body and the trunk stays upright. So in softball pitching, the highest forces at the shoulder occur from front foot contact to ball release. And this is the best male pitcher in the world, Adam Foucault. I'm sure I'm offending some Aussies and Canadians by saying that, but his mechanics are textbook. And so you can appreciate how there, in the second picture here, how there are probably superiorly directed forces occurring to compress the shoulder and resist distraction. You can see, you know, he's done a really great job of internally rotating at the back hip, his arms nice and close to his side here. And there probably aren't sheer forces occurring at the shoulder given his biomechanics. Barentine et al, way back when in 1998, published a biomechanics paper on softball. And so he was a student or a fellow in the Andrews group at the time. So this is Dr. Andrews and Fleisig's group in Alabama. And they found that distraction forces at the shoulder in softball were similar to forces at the shoulder in baseball. They just occurred at different times. So highest forces occur during the acceleration phase of the softball pitching motion, but the highest forces at the shoulder in baseball occur in the deceleration phase. Of course, there are, you know, if you have really terrible mechanics, you're gonna get some wonky forces at the shoulder in baseball, but, you know, kind of classically in that acceleration phase, then forces at the elbow in baseball are higher. Internal rotation torque, so that last like bit, whether you're throwing overhead or underhand, that internal rotation torque is similar. And in both pitching motions, the biceps is involved in resisting shoulder distraction. And it's thought in softball that the biceps is involved even more than baseball, because as you can imagine going from here to here, there would be some kind of resisted elbow extension and so the biceps is anchors, is holding, you know, everything in place as the arm goes through extension in an eccentric way. Dr. Warner went on to show that from her analysis of high level pitchers that lower distraction forces, so, you know, better joint compression was associated with a longer stride, a bent but firm front knee at landing and an open position of the hips, as well as more elbow release after ball release. So, you know, she was the first to suggest after Barentine and colleagues that it is the whole body working together to maximize the performance of the shoulder, not just the shoulder and arm itself. Dr. Oliver, when she was at University of Arkansas had recognized this and as you know, she'd been doing work in baseball on lower extremity kinetics and kinematics and how it relates to the shoulder and elbow. So she took 10 elite youth softball players and measured maximal voluntary contraction of, oops, close that, of the non-stride and stride gluteus medius and maximus muscles. And she found that the non-stride glute medius and max was significantly related to ground reaction forces of the stride leg, as well as ball velocity. We're kind of reinforcing that we should be looking at Montana Fouts' kind of back leg as the key to why she's so successful. Dr. Oliver's now moved on to Auburn and she's doing some really exciting work in softball. And one of her kind of more recent projects before this force transfer stuff has been looking at kinetic chain kind of factors and their association to pain, athletes with pain and no pain. So this is a study looking at 29, I believe they were, she's has maybe two studies, but elite youth softball pitchers as well as NCAA softball pitchers. And she found that the group of athletes with pain had greater shoulder horizontal abduction at foot contact, less lateral trunk flexion toward the throwing side and greater shoulder distraction at ball release. So I'll break this down for you kind of like what Robbie had mentioned. So we're going to hammer this all morning, glute strength sets the proper kinetic chain sequencing. So if you had a weak glute on the back leg or the non-stride leg, then the stride side would likely kind of collapse down. So if I go back to this, you know, at this top of the backswing here, if this glute was weak, this pelvis would drop and this foot would land early and the arm wouldn't have the time to get back to that 120 degrees. And so you can see here that the scapula would probably be elevated off the rib cage if that were to occur. And the whole kinetic kind of unraveling would be disrupted and pitchers would probably end up pushing the ball, resulting in greater shoulder distraction at ball release than the pain-free group. So I can't take credit for the force funnel term that Dr. Bowers was referencing. My mind was blown by Dr. Kibler, who gave a talk at AMSSM a couple of years ago now, I think it might've been 2016 in San Diego, where he presented this idea of the scapula being a force funnel. And myself, you know, I hadn't really ever put together where the kinetic chain would be disrupted, you know, by glute med weakness until hearing that lecture. And really it is, if, you know, the back is weak, then this drops and this lends early, and then that's elevated and the whole force funnel concept can't occur. So I thought I'd show you a few videos of pitchers. These are kids that I've worked with over the years relative to the gold standard. If this is that acceleration phase that we're most, you know, interested in, you know, what are some common ways that this breaks down? So here's, these kids are probably 15, 16. And this is a pitcher pitching with shoulder pain. And it can be, you know, you know something's off with her mechanics after watching Montana, but it's kind of hard to pick out how. So I would, you know, if someone brings you a video in your clinic, I would watch it first full speed and then go try and advance the film to the mechanics checklist, right? So here's her wind up. So she got a bit of a cheater step and maybe she's already turned a little too early stride. So she's nice and long there, looks fine. She's not swimming her glove, but whoops a daisy. She's like off the ground back here. So that's called a crow hop. And then her back foot lands and she's doing her best to try and turn, but she hasn't engaged the back femur to internally rotate. And so her hips and her shoulders are kind of rotating at the same time to try and sling the ball through. That's kind of the term I use for this type of pitching motion. And so you can see, you know, there's no wonder the back of her shoulder is hurting. You know, her rotator cuff is trying to absorb all the force of throwing the ball kind of in the high 50s towards the catcher. So she's really just throwing with her arm here. She's not engaged her lower body at all. And her trunk lean is towards me, the camera person, rather than towards her throwing side. This is another athlete. She went on to play college softball. She's currently playing division one softball and played on our junior national team. If you look at her, you're like, well, that's a pretty good little motion. But again, if we kind of break it down by phase, you can see where her glute, knee, likely and hip lumbo kind of pelvic complex needs some educating. Maybe it's not even a strength issue for her. It's maybe an intention issue. So she gets, I think her foot's still on the ground. She's a little hoppy there, but so she's balancing on her back leg, but she's kind of lost that anchor. It's very externally rotated there. And then as she's coming down to land, you can see there's really no activity from that back hip, internal rotation of the femur. She's kind of leaning forward towards me. I'm sorry, like towards the left side of the screen rather than backwards. And then she isn't over-rotating, but now she's pulling from her bicep. So this is kind of like this pulling type pitching motion. And she throws in the low 60s, but has always been frustrated that she couldn't get much higher than about 63. And she's got tons of athletic potential, but something's off with her intention here of the back leg to try and generate force. It's not over-rotating or under-rotating, just the wrong sequence. This is a picture. She was a little younger than the other ones. She played on our junior national team eventually, and also has a college scholarship to Texas Tech maybe. She throws, that's an easy looking pitching motion, and she throws above average speed. She's also 6'1", so she's kind of a mini Montana Fouts looking at her pitching motion. So that's the end of the pre-motion stride here, looking pretty good, really trying to engage that backside. So she's trying to pinch that knee down towards her front foot or towards the catcher. Arm is at a reasonable kind of 120 degrees, so her scapula isn't elevated. Trying to rotate her hips before her shoulders, and then gets a really forceful internal rotation there. So she was on track, I thought, for her age. Really hard for kids over six feet at 15 years old to engage their kinetic chain. In my experience, it's been something that kids kind of get later in their teens and in college as a concept. So just to kind of further clarify what Robbie was talking about, for your sport, I think it's really important to go through what exactly is happening and what is the sequence is along the kinetic chain. For a long time, it was a black box to me until one of the national team coaches actually asked me, why does the Japanese pitcher, why are they so much better than everybody else? Like, what is it about them? And I was like, I don't actually know. There's lots of things that I could hypothesize, but I knew that Ueno or Yukiko Ueno from Japan just looked a little bit different than everybody else. And so that started my deep dive down the kinetic chain in softball. So for our pitching motion, it's that back hip internal rotation and pelvis rotation starting the pitching motion or starting the kinetic chain unraveling after that stride. And then you get this upper trunk rotation, arm adduction, elbow extension, and then a forceful shoulder internal rotation motion. So this is a recent paper by Dr. Oliver's group at Auburn looking at energy flow of the softball pitch. This is really exciting data to see because it kind of supports this idea of the kinetic chain unraveling. So let me just break this down for you. So this is distal segment power. This is top of backswing here, front foot contact, and then ball release. The solid line is the pelvis. And then this line here is the trunk, humerus and forearm. So you can see at front foot contact, negative is energy going out and then positive is energy coming in. So you have energy kind of, I guess the idea is coming out until front foot contact where you're kind of maximally rotated the pelvis and then the pelvis starts rotating and transferring, oops, energy up the kinetic chain here. Then the trunk does the same thing, the humerus and then the forearm out through that kind of distal segment. They found that the magnitude of outflow in the forearm and humerus is associated with ball velocity, which is no surprise to anybody. So these are the two best in the world right now. You could argue, you know, Cat Osterman should be on here as well if you're a softball fan, but this is Yukiko Ueno from Japan, two-time Olympic gold medalist and Japan just recently successfully defended their gold medal. And then this is Monica Abbott, highest paid softball player in the world. She is the first woman to have a million dollar contract. And you can see this hip shoulder separation. So to your point around kind of thoracic mobility and, you know, exactly how are we transferring force through the kinetic chain? You can see Ueno here has rotated back towards the catcher and she has incredible flexibility through her thoracic spine. And then her scapula sitting nicely on her thorax here when she's ready to really forcefully, internally rotate that arm, keeps it really simple. Same with Monica Abbott here with an eye of faith, given the jersey, you can see her hips are rotated because her back foot's doing what it, her back leg's doing what it needs to do. Shoulders are a little less rotated. She's going to rotate, rotate, arm's going to come down, forceful internal rotation. This is a really great picture of the same concept from up above. So in terms of what I like to look at in the office, I give my throwing athletes the Kerlin-Job Orthopedic Clinic questionnaire. If they score below 90, this has been shown to have a higher risk of subsequent injury kind of in the season, preceding season. Do a good history and physical exam. And some of the things I'm looking for are passive supine range of motion of the shoulder and hips, looking at scapular dyskinesia. And so that's having the athlete face away from me and raising the arms out to the side as well as the front. I don't do the Y balance test in my clinic and I don't do a jump test in my clinic, but we, as part of my fellowship, my sports fellowship at UBC, we did a kind of head-to-toe assessment of the baseball and softball athletes and came up, I'll come back to the slide, but came up with this player report where we looked at their, all these evidence-based things kind of associated with throwing injury. So we looked at grip, total range of motion, range of motion difference, GERD, Y balance test of the lead leg, Y balance test of the back leg, we called it stance leg, and then the leg lowering test. So in a perfect world, if I were Robbie chairing baseball medicine at Emory, I'd think about including it in my assessment in a perfect world with limited resources. That's where I think you live, Robbie. Maybe that's just your Twitter persona. And so you can see, this is a table of kind of evidence-based risk factors for throwing, pitching injury, which is largely work of Dr. Zremski and a couple others to put this all together in an evidence-based way. But you can see that lumbopelvic instability and scapular dyskinesia are two factors that are modifiable we could focus on. All right, so I'm on time. Yes. Just to summarize, softball is a popular women's and men's sport, particularly in the month of May. And if you haven't had a chance to tune in to the Women's College World Series, I would recommend parking yourself on the couch. It's one of my favorite events to watch. The acceleration phase of the windmill pitch is where injury is likely to occur. Proper sequencing probably starts with a non-stride leg before front foot contact. And softball and baseball both have high forces at the shoulder. Proper kinetic chaining results in higher ball velocity and probably lowers injury risk in softball like it does in baseball. This is my contact information. If you ever want to talk softball, I'm game. That was awesome. Thank you, Dr. Holtz. There's one question in the chat. It says, or it asks, is there a high instance eccentric overload or injury on the adductors in the medial knee in the back leg or the push leg of the softball pitcher? Yeah, that's a great question looking at this other question. You know, the back leg, as you see people balancing on that foot, you think, oh, that's not great. But honestly, there's not a ton of like back leg or stance leg or non-stride leg injuries. People have had kind of, in my experience, stress fractures of that back foot and ankle if they balance on it too much. But there isn't any kind of adductor injuries. Although that gets my kinetic chain kind of hat thinking, like perhaps it's not weakness of the glutes. You know, in some of the athletes I'm showing you, it's maybe tightness of the adductors not allowing for glute activation. So as someone who uses dry needling a lot in my practice, I'm thinking, hmm, maybe if I address some of that tightness then maybe we'd get more activation of the glutes. I will say that when I was finishing my playing time at UMass, that's where I did my undergrad, I had this brilliant idea because UMass has a really fantastic biomechanics program that I wanted to study softball biomechanics. So this was 2001, probably around the time that Gretchen started. And UMass was, and the question I wanted to answer was everyone around me seemed to have a stride leg or lead leg ACL injury. And I was like, pitchers never injure their non-stride ACL. Like everyone's injuring their stride ACL and it was often in another sport like soccer, rugby or field hockey. And I was like, there must be something to this. Like, we should look at this. And unfortunately the biomechanics lab at UMass was and still is a really running focused lab. And so they said, no one really cares about softball biomechanics, move along. So I ultimately did my master's degree in energy metabolism which led me down the road to medicine. But that's funny to think, I actually just saw a paper about ACL injury risk in pitchers and I thought to myself like, people care. So just a few years too early. Awesome. All right, well, that was wonderful. And next up is going to be Dr. Krabeck and he is going to talk from the perspective of the swimmer. All right, great. Thanks everyone. And thanks for having me. Give me a moment here to share my screen and begin this talk. I want to thank Dr. Zerimsky for reminding me. It's been a while and I'm getting older since that last time, but actually it's been great to see the work that you've done in your career. And I was glad I could be part of that journey. Also like to thank the Academy and everyone today for being here to learn about swimming. And I'm really excited about the fact that swimming is incorporated in this. It's kind of near dear to me in regard to the sport. As before we get started, just to disclose that you travel with the team as a national physician and get support for time when we travel. So that's really appreciated as well. All right, so let's talk about the objective. Similar to before, I've been fortunate enough to work with some of the key swimmers in the world. For those of you who are wondering, Michael Phelps on the left, Katie Ledecky on the bottom, Lily King on the right, and Reagan Smith, who is one of the backstrokers who has had a really successful career. Like everyone else, we're going to focus on defining the kinetic chain. Now as it relates to swimmer and take a deeper dive into that. And I think by understanding how the kinetic change and the uniqueness of swimming in its medium, the water, plays a role in how we move, how we optimize things, as well as discuss the role of how the breakdown in the kinetic chain can lead to dysfunction and risk of injury to shoulder. And then I'll just give you some basic tips of some things that I sort of look at in regards to the kinetic chain in regards to the swimming athlete as well. So, you know, I just start out, swimming's unique, right? They spend a lot of time in the water training and the extent to which they can compete varies. And the kinetic chain becomes so important. So what do I mean about this? For those of you who follow football, there's the catch. Well, in swimming, there's the touch. So in 2008, Beijing Games, Michael Phelps is going to break Mark Spitz's record. He's competing in the 100-meter butterfly and he's behind, actually, the last part. And he makes just an all-out, you know, sprint there to finish at the end. What's fascinating about this is he, in the middle of the stroke, realized he had to do a half stroke at the end of his butterfly in order to time not gliding in. And I think you can appreciate here how he is all outstretched using all of that length of that kinetic chain to basically out-touch this guy by 0.01 seconds, which was the difference between gold and silver and allowed him to tie the record for the most number of gold medals, which was seven as well. In 2017, Katie Ledecky on the right was just so dominant. And you think about her swimming technique and how she uses her kinetic chain to control the water. In the 1500, she won by 19 seconds. That's like time to bake a cake and deliver it to your friends in the swimming world as well. So we're going to explore a little bit more just how swimming really utilizes the kinetic chain in a slightly different way as we go through. So before we get started, let's just talk about some of the physics behind this, because I think it's important, the fact that we're in the water and that it reacts with our body. So if we think about Archimedes' principle, this is a component of the fact that a fully body or partially submerged body of fluid is buoyed by forces equal to the weight of that fluid it displaces, right? So we have our weight of our athlete and there's a buoy force with that. And then as we're going through multiple planes, we have to think about our thrust force or drag force or how we're moving through the water and the surface and the resistance that goes through there. And what's key about this point is that our bodies have the center of mass in general, and then there's this buoyancy force, the force that is going to equate to us moving and being displaced as well. And what I want you to think about is that that's not necessarily the same, and that can really impact one's ability to transfer through the water. And this is a great example on this slide, I think of showing how, just in regards to the center of mass, the red dot, and then that buoyancy force, which is impacted by our ability to take in air and how that impedes things, tilt this too far down or too far up, then you get more resistance and that will impact our ability to move through the water. Keeping it optimized and straight allows us to flow through accordingly. And swimmers have to learn how to manage that balance between what they go through. And then the second thing to think about, and then short little lesson on physics or a reminder on physics, is Newton's law. So basically an object at rest remains at rest if it's acted upon and moves forward, and then that motion can change based on speed and direction by the forces it's going through. Newton's second law, which is that how fast or the acceleration we go through is impacted by not only our mass, but the amount of force we're applying. And then three, for every reaction, there's an equal reaction as well. And this is equal and opposite reaction as well. So let's take this and then think about how we're gonna make this specific to swimming. So you'll see through here, we're gonna go through this video, the first law that the swimmer in motion stays in motion. And we have this propulsive drag or force that pushes us forward through the water itself as it's going through, but we're also battling the frontal drag or the frontal force that is basically gonna slow us down. And it's a constant battle. Speed, acceleration is the balance of these two forces. So as we're moving through the water, we're trying to optimize the kinetic chain, the biomechanics, and if we can minimize the drag, then we can go through. And then for every force, we're pushing through the water. So for every action, there's an equal opposite reaction. So the medium of being in the water really impacts how we move through that as well. And if we have to really understand these principles of how we float, how we're optimizing center of mass buoyancy and these propulsive forces through to move as quickly as possible through the water as well. And so we have to also think about resistance and there's different types of resistance that we have. There's this frontal resistance. We talked about that, but the water coming through as well. There's the resistance in relation to the friction along the body itself. And that's why swimmers like to shave down, right? To minimize the resistance and might have a specific type of suit. And then there's this eddy resistance, the swirl of the water as it goes through that can impact your ability to move through that medium as well. And so swimmers will try to maximize their streamlined position as they go through the water to optimize water flow and minimize drag. And I like this as a great example of really understanding that concept which swimmers are constantly battling. And it really gets interesting in regards to those age group swimmers. Those younger swimmers are going through or learning the biomechanics. And then as they grow, it changes the way the water may potentially flow through them. And that could be a big struggle which is why swimmers will advance in time, decrease in advance in time again. And then let's take it all away. So we talked about in general, but we also have to think of the extremes, the hands and the feet in regards to how these can interact with the medium as well. So here we just sort of get a sense of how water can flow past the hand and the difference between just rotating the hand a little bit internally, externally, the drag force that pushes can make the difference of a 0.01 second be for someone winning or not winning an event. So I want us to just think about the whole concept of the whole body itself as a swimmer goes through there. And then this is just to remind us that swimmers have different body types. And so how water is gonna flow through the person on the bottom versus the top really vary based on the various factors of how they're designed, the length of their body, the percent body fat and how they can optimize the kinetic chain in moving through the water itself. Okay, so let's think about swimming. So your mind probably goes to the fact that a swimmer, right, there's freestyle, there's backstroke, but swimming events start with the start, right? And it's similar in a sense to thinking about how you throw a baseball, right? There's a point where you're on the block or whether we're gonna look at freestyle here and we look like someone like Caleb Dressel. So here's Caleb Dressel, University of Florida, by the way, who has a really fast start, 0.6 seconds, which is not the fastest per se, but quite explosive in regards to how he can get off the block. His reaction time is quick. He has this high hips kind of posture as well. He's gonna load everything while he's on the block and taking that potential energy. And then explosively, he's gonna reach out. And one of the things that's unique for Caleb that people are doing more and more is how he takes that potential energy, utilizes the force of his arms and really hyperextends out that shoulder region to get as much energy moving forward as he's about to get into the water. And this, as you develop more with swimmers that you're evaluating, you start looking and these athletes practice the starts. It's just as much, and here in this picture, you could see just on the bottom here, how his toe is subtly flexed and activated to kind of get him moving through. So if we think of it a bit conceptually, the kinematics of all this, right? There's this initial compressive force where you can see the center of masses. And then as they explode out at an optimal angle to move forward, bringing the arms up, and then there's this attitude of entry into the water. And swimmers work continually on all this as well. And if we break it down to this kinetic chain, I want you to conceptually think about that loading, contracting of all those muscles in preparation for that dive, that storing of that potential strain energy, and then the sequence of activation of all those muscles that really start with our core, with our gluteal, and then transfer all the way to the toes and then into the upper extremity as the swimmer reaches out to optimally get into the water. And all happens within this case, 0.6 seconds, which is huge. So then we're in the water and here's Simone Manuel, one of the great sprinters. We're just getting started, right? So there's lots of work that's done in this underwater. So what they're trying to do, and traditionally you'll see everyone doing their dolphin kicks underneath here, and the breakout, that surfacing of the water. And this is the phase where you can have the quickest movement and motion or movement through the water to really gain an advantage in swimming as well. And we're not gonna go too much detail into this, but I just want to use this slide to kind of highlight the kind of kinematics of an underwater dolphin kick. And just understanding that, right, different joints are moving at different angles as well. Here in this slide, you can see how the black on top is representing the motion of the knee, which in order to get the hip and the knee and the feet moving in such a greater motion takes a coordinated effort, which strength through the core while in the front maintaining streamline through the shoulder and elbow, for which you have to have the appropriate flexibility and strength as well. And this allows the athlete to move through the water as quickly as possible to gain an advantage as well. And then we have our stroke. We finally get to the fact that now we're gonna compete in whatever we're kind of competing in. Here's Katie Ledecky is one of the best strokes in regards to long distance as well. And so, you know, there's basically four different types of strokes, freestyle or sometimes referred to as crawl, backstroke, breaststroke, and butterfly. What's important to know is that swimmers, although they may specialize in a specific style of stroke or in distance, whether that's sprint or long distance, they all train in all of these different strokes throughout the course of their career as well. So let's break down and look at freestyle here in the phases of this. Just like with baseball, softball, any kind of sport, you can break the phases of swimming into basically four phases that have to do with the setup or entry. In this case, when the hand's coming forward, the athlete is reaching out, rotating with their hand to start catching the water that's gonna hit all of the surface of their body. There's this pull phase where they're starting to grab that water and move themselves forward and take advantage of Newton's third law for every reaction, the other reaction. There's more of a kind of pull phase where all of a sudden they've kind of advanced over the arm, and then a recovery phase where they have to set for a recurrence. And we have to think about this in the multiple planes. So if we think of, in essence, these stroke phases on the bottom, you could see how the shoulder goes from this abducted flexed internal rotation to more of a full external rotation posture. And there's activation of a whole bunch of muscle groups depending upon the system. And that's what some of the biomechanics has basically shown. So with that hand entry, we get that upper trap rhomboids kicking in, and this is specific to the shoulder, activation of the pecs as we're starting to, and stabilizing of the shoulder as we're starting to do the early pull through, activating the lats and the subscap, and then their deltoid as we're going through recovery. And for those of you who are visual, I really like to look at this. I think this does a great job of showing just some activation of the various different muscles group. But what I want to draw your attention to is the whole length of the body in regards to the swimmer, right? They're activating various different things as they go through entry, push-pull phase in recovery, but you can see how they're continually activating the lower extremity, and most importantly, the core. And it's this connection from the hand to the foot that is constantly going on, and the athlete is continually trying to optimize as they go through. And any break, as you can imagine, this can lead to injury. If we think of it in regards to the backstroke and the phases of the backstroke and activation, similar thing in regards to hand entry, but now the shoulder in a slightly different position, this extension with still some internal rotation as they're coming through, they're activating similar muscle groups in the shoulder in a slightly different sequence, but you can get a sense of how that athlete can move through the water as well in regards to the extremes of motions of the shoulder and muscle activation. And in a similar fashion here, I like this picture again, really showing us how this athlete is activating the structures around the shoulder, the core is activated throughout, and you can see with the kicking motion, they're optimizing head-to-toe, fingertip-to-toe-tip as well in engaging that core as well. And then if we look at the breaststroke, here you can see I didn't break down all of the specifics in regards to the breakout of entry and such, but I do like this again, showing the activation. And here you could see even more activation of the core and the back and providing that force to push the water through, given the mechanics of the breaststroke. And then we can go into the fly again as well. And this is one of the toughest, really toughest strokes to do, especially for long distance. If you get any swimmer who's gonna go swim for a 200 meter fly, and they'll just be like, oh man, that is a tough sport. But here you can see the coordination and activation patterns of the muscles of the kinetic chain. And for me, I think this provides again, another great visual understanding of how important it is to activate all those muscles in the proper sequence in order for the athlete to continue to go through the water. So that's great. So now we've entered the water, we've swimming our stroke, and now we have to hit a wall. So we have to think about flip turns and the optimization of flip turns. And similar to the start, I mean, this is a plane, you're coming in horizontally, but you have to think about the energy that's coming in, the optimization of that speed, the timing to touch the wall and the timing that comes off the wall as well. And if you really think about it, it's similar in the start in the sense that you're taking this potential energy that you have, that acceleration you're going through, and you're trying not to slow down and you're trying to spin or flip as efficiently as you can so that you could reactivate that sequence of explosive movement that allows you to get back in the other direction. And depending upon the distance, obviously the number of times it would do that will depend. But again, swimmers can spend a lot of time, especially age groupers who come in, they're in practice and they're swimming and they're focused on their stroke mechanics. They may not be appreciating the extent to which the flip term becomes that much important until they get a greater command. So with that, that's our basis for understanding how really the kinetic chain in swimming, somewhat different in the sense that it's this whole body head to toe, not that when you're throwing a baseball or a softball or lacrosse or tennis is in it, but this is happening continually every single cycle of when a swimmer is swimming. And if you think about the cycles of swimming, an elite swimmer will basically swim six to 10K per day or session, depending upon what it is, they may swim five to seven times per week. If you think about that, that can be 60 to 80 kilometers, 30,000 shoulder strokes per week for which we're continually churning and going over and moving. And so you can imagine that a breakdown in the kinetic chain can definitely lead to shoulder dysfunction, back dysfunction, as mentioned, even in the breaststroke and the knees as well. So let's explore a little bit more about the type of injuries and what can go on. And Dr. Zarimsky pointed out this paper. This is a bunch of physicians who were involved with the swimming world. And I think it just provides a nice diagram for the variety of factors that can impact a swimmer. Today, we're focusing on those two issues about the strength, muscle imbalance and faulty mechanics that can lead to potential injury of the shoulder. But obviously there's other things in regards to training volume as well. So what do we know about injuries in shoulders in swimmers? And this is a compilation of some of the studies that are out there. What's interesting overall, there's some good databases, NCAA data that is quite helpful at the elite level. There's databases that will look at world champions in the Olympics as well. For the age groups, there really isn't as much, I think, because it's just much more challenging to design a study that assesses athletic exposure, that means. But if we look overall from what we can surmise in regards to injury, whether that's through the season or at a specific competition, we don't have great rates in regards to these age groups, so those younger swimmers, but we can get a sense of what percent of individuals have complained about shoulder injury in those age groups that's listed here. As they move into high school and college, you can see that the rate of injury increases, probably because they've been swimming for much more, the intensity of the training increases. Often in high school, which is interesting, high school swimmers often a certain percentage swim for their high school, and then there's a certain percentage that do club and high school, which wraps them into that age group swimming component as well. But you could see how a good number of high school kids potentially complain of shoulder pain, at least in these studies by Post and Schroeder. But if you look at the athletic exposure component, the number of times they're kind of training, it's relatively low compared to that college athlete. And there are some great studies that suggest that as athletes move into college, and especially when they go from freshmen to senior, that ramping up or change in the amount of workload they're doing can cause injury as well. I wanna highlight on the right just some of the other things. You can look at other types of injury, trunk in essence is spine, and that the spine actually is like the second most common reason that those athletes have issues. And then obviously the knee would be the third. And there's some unfortunate examples of elite Olympic athletes who've really kind of bowed out because of spine pain. In regards to world championships and the Olympics, so here's some recent studies suggesting the number of injuries per athlete. And this is specifically during the event, and this is what potentially can keep me busy when I'm traveling with them as well. Now, if we look at risk factors for injury, we're not gonna go through all the studies, but this I think summarized really nicely what we know if we look at kind of systematic mental analyses and summary. So in short, we need to do a better job of providing better study. And I think this is challenging the swimmer. If you think about the medium they're going through, we can screen for certain things, but looking at the biomechanics in the water has its own challenges. What I wanna highlight for you is probably the key things here is some of the good evidence suggests competition level, which we figured out could be a risk for shoulder pain. Previous injury, which allows us to ask questions. Talk a little bit about training volume and load. So there's a bit of a discrepancy in how people train. So if they're training and the load management's too much in that younger athlete, that can lead to injury and the ratio of how they work. Training errors, interestingly in this study, hand entry, you're more likely to bury your hand. You're less likely to get shoulder issues, but it'd be probably because you're modifying things, but then your performance goes down and eventually the whole system breaks down. Probably one of the key things that suggested was that posterior shoulder endurance strength was a big predictor of potential shoulder injury. And then the listed some other things there about laxity or instability as well. For this study, and I thought this was fascinating, right? Because we think about the kinetic chain in the scapular, but there's some lower level evidence in regards to how the kinematics and strength may be helpful, but we need to do a better study in trying to figuring out that scapular, that funneling of energy and how that plays a role. And then we have non-shoulder injuries here. So it was a recent article that came out in the past year that looked at other types of regions of the body. And I just want to highlight again, we need to do a better job in trying, in regards to our studies in regards to figuring out better evidence, but here I've listed some of the other factors that can play a role to whether that's age, the type of stroke, but they were lower evidence studies where they followed cohorts. And it's just important to understand that that's part of the issue that's going on. Here, we're going to look at technique. These are some of the simple things that you could look at and figure out on your own. Again, people have phones and they can take videos and you could look at them. We're going to talk about a few of these. On the top left is just about arm and hand placement, whether it's too far out or too far down. On the top right, you can see this person is definitely getting a lot of resistance, probably because they don't have great core and how they're not balanced in regards to how they move through the water. On the bottom right, you could see someone crossing over midline. So they're over stretching too much, which can lead to injury. And then here on the bottom left is a backstroke or it has to do with someone who maybe isn't rotating enough or their arms extending too much, that can lead to injury. If we want to look at it in regards to biomechanics, here's a great example. I think that Russell Mark, who's somebody I've worked with in the past through swimming. On the left here, and we can slow this down a little bit. As this person's coming into the left, this is our good stroke there. Hands coming forward and through, they're capturing the water, they're pushing through, elbows in a great position as they're coming through, they're not crossing over and you can look how streamlined they are. The person on the right, what you can appreciate through here is just how they're crossing over. They're just losing energy and they're putting extra talk in internal rotation, potentially impinging that shoulder to coming through their arms way too far straight overall. And they're not optimizing the rotation of the shoulder compared to the person on the left. If we were to look at the backstroke in a similar fashion, here's this person, great rotation. They're walking through, they're capturing the water and taking advantage of the pushing through where this person on the right is really flat. They're just, their arms coming out extremely wide. And again, that's going to put a lot of torque and pressure on the shoulder itself. So these are some examples of things you can definitely talk about with the individuals as you're trying to figure out what's going on. And then we'll finish up in a few minutes more in regards to the evaluation of the shoulder or evaluation of the swimmer, shall I say, in regards to the kinetic chain. And the first part is that like any sport, athletes are very different and their body composition is completely different. And we just kind of have to assess those individuals as they are and highlighting the importance of that. But what they all share is the sense of how this kinetic chain works. And so in regards to thinking about stability and mobility of the different joints in regards to the swimmer, we're going to use that fact and look in our assessment to see, see where is there a breakdown in the kinetic chain itself as well. So here, just highlighting a few things in regards to the evaluation of the swimmers. As you can see on the left, swimmers often, because they spend a lot of time doing freestyle, they get sort of this hunched over posture, arched lower back. They get tight in regards to the shoulder and pecs region. They can have tightness in their neck muscles as well that you have to think about. As you can see in the lower bottom, there may be some asymmetry in regards to muscle bulk or the positioning of the shoulder as well. Although the research wasn't strong for necessarily the scapular itself, I still think it's worth looking at, especially in someone who has an injury. So we always can assess if someone has a shoulder injury to look at the kinetic chain and the scapular motion to look for dyskinesis as well. And you might utilize some scapular assist techniques to see how that changes things. If you really think about it on the top right, it's a closed kinetic chain in the sense that we're interacting with the water. So you want to not just look at someone as they're moving an open kinetic chain, but also close kinetic chain to see if they can activate the shoulders appropriately, utilizing the ball or doing some circles as well. And then as I mentioned earlier, this posterior shoulder endurance test. So this is something where I like to get the athletes down on the table and really just push down and see what is their strength in their posterior shoulder. And you can do that in both like a Superman position out 90 degrees and then with their arms back. And that way you can isolate out the posterior shoulders in both the upper middle and lower area. And we can get a sense if they have good strength. We're kind of like Cadillacs in the front, Volkswagen's in the back, right? We've got to balance that strength out. And then we want to think about the core. And I love putting athletes in the center of this quadruped position as well and have them stay there for a little bit. And this gives you so much information. I explain it as like, look, you swim in this posture. This is a way to see this. But we get a good sense of shoulder stability, core stability. And often what will happen is if you let them hang out there for about 15 seconds or so, or sometimes 20 seconds, you'll start seeing that the arm drop or in this case on the left or the leg starts coming down or they start getting unbalanced and rotating in which case, you can see the fatigue. They might arch their back and this is a quick way. And often when the parents are there, they'll be like, whoa, look at that. And you're like, yeah, look, they're not engaging the full core kinetic chain linkage between the hand and the foot. And that's a great example to figure that out. And then you could also on the right, just as a reminder that as you're working through to think about what we went back to at the beginning which is this buoyancy. How does one activate and diaphragmatic breathing and how are they filling their lungs? And often when we're working with therapists that there's some postural restoration things you can do in regards to breathing that could be just as helpful for that balance. And then lastly, let's not forget about jumping, right? So even just looking at a squat jump or if you have the room to kind of do that just to see how they compress, get all that potential energy and explosiveness which has to deal with starts, which has to deal with pushing off the wall, that's key. And in the clinic, you can look at other things in regards to balance. I still use single leg stance, gives me a good sense of the core as well. I actually like adding in the opportunity where you have the athlete close their eyes. So you take away that visual and you can get a good sense of how much they control of what they have with the whole kinetic chain. And it's not uncommon for people to break down pretty quickly as well. And then the last thing I'll just kind of leave you with here and this is a nice little chart. Don't forget that swimming actually has a bunch of equipment and depending upon the type of injuries that they have these can impact the forces here. So just realize that when you're counseling someone about recovering from injury return to play that you need to take these things into account. So in summary, the kinetic chain, pivotal role just like in any other sport as well. There's some unique things in regards to the physics and forces that impact the swimmer and the medium that they're going through. Obviously a breakdown in that kinetic chain can lead to significant injury which is often in the shoulder but can include the back as well. And like any sport and individualized evaluation hopefully we walk away today with a couple of pearls in regards to the functional evaluation of those individuals that can be helpful in returning those athletes to play successfully. And I wanna acknowledge having the opportunity to travel with the team as well and some of what I've learned from the physicians and therapists and coaches as well throughout. and thanks for having me talk to you today. That was that was fantastic. I mean Dr. Krajewicz was really able to summarize the complexity. I mean the swim stroke is really in-depth and a lot of folks don't really understand the the intricacies involved in it so that that was fantastic. With that we're going to go on to Dr. Micheo and let him kind of delve a little deeper into the scapula. You're on mute Dr. Micheo. Yeah let me try to share my screen. My slides are open. Let's see. I'll share. Can you see my slides? Yep. Perfect. Got it. So thanks Jason for the invitation and Brian Thompson for help us organizing this and the academy for putting this kind of information out there. Certainly was not out there when I started in practice over 35 years ago. Probably this guy will saw me before I saw it for many years but I had the pleasure of meeting Ben Kibler in the first team physician course organized by ACSM in 19 I think 86 or 87 and actually I used to play tennis. I still do but got to play him, know him, and learn a lot from him. I have nothing to disclose for this talk that would affect this talk. My objectives are very simple. This is going to be a practical talk. A lot of the information that I have for you already has been mentioned in the previous talks that were excellent and certainly I learned quite a bit. So I want to present some basic concepts of the function of the scapula and the kinetic chain of the overhead athlete. I'll talk a little bit about the scapular dysfunction, how you could look at this from a clinical presentation standpoint and what findings you see in clinical examination and at the end I'll briefly highlight some management strategies to address this scapular dysfunction. We know that the shoulder joint has mobility at the expense of stability. Certainly makes it clinically challenging to improve some of these athletes with significant hypermobility. Shoulder function depends on optimal function of the dynamic stabilizers, which the scapular stabilizers are one of them, and preserve static stabilizers such as the glenohumeral ligaments and the capsule. The scapula certainly is a critical component of the thrower's kinetic chain and we need to understand other critical components of this kinetic chain in order to be able to get the athlete back to asymptomatic performance and excellent performance in the sport of his choosing. So what is the kinetic chain? And this has been mentioned quite a bit today, but I just want to highlight the concept that over 50 percent of the forces of the acceleration comes from the lower extremity. So the activation comes to the scapula through the trunk and the scapula and shoulder are funneled and a force regulator. Certainly, as it was mentioned, we need to understand more the individual components of the kinetic chain, including the trunk, and how they interact with the scapula. The arm is a force delivery mechanism for the end of the action. The components of the kinetic chain evaluation for our group include the following. So when we see a patient with an injury, we look at five things in the clinical context. First, the role of the scapula in the throwing motion, then we add shoulder aroma adaptations in the overhead athlete. The other thing we look at is for the rotator cuff, how it functions in the throwing motion and changes in the motion, be that adaptive or abnormal. Then we try to identify kinetic chain components, including the lower extremities, and something that we need not forget is the function of the static and dynamic stabilizers. Some of our patients, particularly young patients, will have multidirectional laxity bilaterally, and we need to understand that because that would impact the way we get them back to normal function. The scapula we know is a triangular-shaped bone with superior, lateral, and medial borders, and it articulates with the posterior ribs. It's not a true joint. It has multiple angles or degrees of motion. It goes upwards and downwards, tilts anteriorly and posteriorly, and could protract and retract. It is deviated 35 degrees anterior to the frontal plane, and the concave glenoid fossa articulates with the humeral head, allowing significant degrees of motion for the shoulder joint as well. The biomechanics of the scapula includes that it moves in coordination with the humeral head, maintaining the shoulder center rotation for all angles of throwing or overhead motion, should retract to elevate the acromion and facilitate the position of cocking in the early phases of the throw, the tennis serve, or the volleyball spike, and it protracts with this motion to maintain contact with the humeral head and help with deceleration and dissipation of forces, which are significant, as it was mentioned in prior talks, for the rotator cuff and other soft tissues. Scapular stabilizing muscles certainly are important when we're addressing scapular dysfunction. We know that of this group of muscles, the upper trapezius and the lateral scapula in particular tend to be tight and may become weak. We know that the middle and lower trapezius become inhibited, and that affects certainly the position of the scapula at rest and maybe with activity, and the serratus anterior, a very important muscle that inserts in the inferior angle of the scapula, becomes inhibited and causes a significant degree of scapular dysfunction, particularly in end range of motion. The role of scapula in the kinetic chain, and this has been widely studied over the last 20 years, we know that it's the stable base for shoulder activity. It activates prior to rotator cuff activity, prior to elevation of the shoulder, and it's also the origin of the intrinsic muscles of the shoulder. This is a very important factor because positioning of the scapula at rest and with activity certainly affects the force couples of the shoulder joint. It is a link in the proximal to distal kinetic chain and is the funnel that transmits forces from the lower extremity through the spine to the upper extremity. Certainly, it works very closely to the thoracic spine and the cervical spine, and these are areas that we need to look more in the future to see how we can affect them with our treatment and treatment strategies. This is a drawing from Jack Ropo, who is a biomechanics and tennis coach. You look at this depiction of the simplistic depiction of the kinetic chain, where we know 50% of the forces come from the leg, transmitted to the trunk and back, to the shoulder, and then to the elbow and wrist. The smaller segments of the kinetic chain has a lower capacity to produce force and acceleration. That's why dealing and identifying dysfunctions in the bigger or larger segments of the kinetic chain is quite important for us that are dealing with rehabilitation and return to play in these athletes. Proximally, as I mentioned, the scapular muscles are very important because they fire initially to position or stabilize the scapula in order for the deltoid and supraspinatus to be able to elevate the shoulder. Then the infraspinatus and teres minus rotate the shoulder externally, and at the end of the pitch, prior to that, we have the subscap, the pec major, and the lat dorsi, which are extrinsic muscles, these last two muscles, which accelerate the shoulder. Then, at the end of the motion, significant forces are applied to the posterior elements, including the rotator cuff. So we know that the scapula is important in the earlier stages and the later stages of throwing, with significant tensile and shear forces applied to the scapular stabilizers. So we know that scapular dysfunction is present in a high percentage of shoulder injuries, and it may be present in asymptomatic overhead athletes even prior to development of symptoms. Some authors mentioned that over 60% of overhead athletes may present some component of scapular dysfunction. It is not clear how to address this in the prevention programs, but certainly, I think, in our practice, we try to look for these findings in younger athletes, trying to train them early on in their athletic career. We happen to work with a high school of sports kids, and we see this quite a bit in younger athletes, so we are trying to address this earlier than later. Protracted scapular position is important. I mean, it's associated to reduce subacromial space. Weak scapular stabilizers is certainly associated with this position. Abnormal scapular anterior tilt, and other things that really affect the scapular function is the anterior chest muscles, which insert in the coracoid process, such as the pec minor and the coracobra achialis. All these may lead to secondary impingement and reduce the subacromial space with dynamic activity, so these are a lot of areas that we need to be looking at when we're talking about scapular dysfunction. Abnormal position at rest, abnormal position with activity, and fatigue and how this affects the neuromuscular firing of the scapular stabilizers. Those of you who have been reading this literature for many years have seen all of these topics, scapular dyskinesia, scapular dyssynergia, and scapular dysfunctions, pretty much synonyms for scapular malfunction during activity. In our assessment of patients with scapular dysfunction, we look at the scapula at rest. We see this young individual with significant lateral medial winging at rest, and then we see this asymmetric scapular motion with elevation or abduction of the shoulder. So we look for both scapular position at rest, which may correlate with soft tissue inflexibilities and weakness of the scapular stabilizers, and then we look at scapular dysfunction with activity that may be related to soft tissue inflexibilities, weakness, and neuromuscular firing deficits as well. This has been described in many, many cases for many years. This was from Janda in the 1980s, and this came out initially from the cervical pain literature, but this really depicts what happens in many of these athletes with shoulder pain and scapular dysfunction. They would have forward head. They have weak, deep neck flexors. They would have tight upper trapezius muscle and levator scapula, and many of them present that this is key in the rehabilitation with lower trapezius and serratus anterior muscles, and as I mentioned, at rest, they have tight pectoral muscles, which would bring the scapula forward and reduce the subacromial space. The other thing that's important to understand is that the scapula is the origin for the rotator cuff muscles, so if the scapula stabilizers are affected, the length tension ratio of these muscles is affected, and this will affect the force couples between the deltoid and the rotator cuff. As we see here in this drawing, the deltoid force vector tends to elevate the humeral head, and the force summation of the rotator cuff muscles is a depressor of the shoulder and the humeral head, so you have scapular dysfunction, abnormal length tension relationship of the rotator cuff. This would lead to secondary impingement as well, so now we will see for a few minutes what information we would like to get from the history and from the physical examination of these patients in order to help us in management of scapular dysfunction. First thing I look for is the age of the athlete, the gender, how long have they been playing their sport, and what is their level of competition. In general, the younger the athlete, particularly male and young females, we look for scapular dysfunction and the association of pain associated to impingement and instability. We also look for volume of activity, competition schedule, and acute changes in volume, and one of the things that we know, at least in Puerto Rico because of the warm climate, many of the young athletes who are throwers play year-round. They don't have the three months of rest that's really required to prevent injury. We look for acute versus chronic presentation, time lost from competition, and this is an index of severity for our athletes. We look for pain that improves with warm-up, thinking of sub-tissue pain generators that persist during activity, make this a more severe tendinopathy or problem with the rotator cuff, and pain at rest or at night, which may be associated with more severe pathology in older and even in younger patients. Symptoms in the early phases are usually associated with shoulder laxity or instability, and in the late phases of the pitch are associated with eccentric overload over the posterior structure, such as the rotator cuff and also of the biceps and labrum complex. One of the things that we really look at, and I emphasize to my fellows and residents, is look at the opposite shoulder looking for atraumatic instability or laxity, and look for history of previous trauma looking for acquired instability in throwers, because this certainly affects the prognosis and the management of the patients, response to previous treatment interventions, mechanical symptoms, which make me think about labral pathology, and complaints of dead arm, which is something that we would look for, thinking more of patients that have shoulder laxity or instability. In terms of the examination, it's key to inspect the shoulder from the frontal and from the side plane and from the back. We look for dominant arm depression, which is very common in throwing athletes. We look for forward head and shoulder protracted scapula. These are proxies for tight anterior muscles and weak scapular stabilizers. We look for scapular winging with dynamic motion, and certainly these are things that we would use this information to integrate to a rehabilitation program. Also, we look for atrophy of the supraspinatus, and particularly the infraspinatus. It's been a common finding that we see in our patients, particularly tennis players and baseball players, that many seem to have atrophy or at least reduced muscle bulk of the infraspinatus and the scapula. This has been described also by Todd Ellenbecker and professional tennis players. This is in the absence of superscapular nerve injury. We see quite frequently this last week, I saw two young throwers with scapular dysfunction, secondary impingement, particularly internal impingement, and they both had significant interest in infraspinatus, either muscle inhibition or atrophy, with pretty good strength of the external rotators. This is something that we look for, particularly in our young throwers. How does this correlate for your planning or treatment? This correlates with tight pec minor muscles, weak cervical muscles, serratus anterior, and lower trapezius, as I mentioned. Rotator cuff muscle inhibition versus supraspinatus or nerve injury is something that we look for, particularly in this subgroup of patients that have muscle atrophy or inhibition in the scapular muscles. Palpation is important. We look for soft tissue pain generators, particularly the upper trapezius, the rhomboids, the rotator cuff, and pectoral muscles, but we also look for tenderness over the bony joints of the shoulder. Reproducible pain over the cervical and thoracic spine lead me to look at these areas in particular for treatment and address them in treatment early on in the treatment course. This may correlate with areas of tissue injury, particularly the rotator cuff and the glandular labrum, and areas of tissue overload that we look for, such as the scapular stabilizers. Range of motion, and this has been mentioned in the prior talks, I think that scapular dysfunction has a lot to do with the resultant loss of motion in throwers. We know that many throwers, particularly pitchers, have an increase in external rotation with an associated loss of internal rotation, but the total range of motion should be normal, 180 degrees. Loss of 10 degrees of motion, total range of motion, we in our practice consider abnormal. Tennis players and other athletes may have preferential loss of internal rotation, known as glenohumeral internal rotation deficit, and here we look for a 20 degree asymmetry between the affected and the non-dominant shoulder. What we look for correlation and the range of motion changes with pain inhibition, muscle weakness, nerve injury, and in particular in the scapular dysfunction, we look for posterior structure and capsular tightness that are associated with this loss of internal rotation, and this is associated with secondary or internal impingement in many of our athletes. Manual muscle testing is a key portion of our examination. One thing that we do is we always make sure that the scapula is retracted at the time of muscle testing, because if not, we may get a false sense of muscle weakness. So this I learned from Ben Kildare a long time ago. So before doing our manual muscle testing, particularly of the intrinsic rotator cuff muscles, we make sure that the scapula is retracted and then we do our manual muscle evaluation. If you find that a patient that you're seeing with shoulder pain symptoms has rotator cuff weakness, always make sure that the scapula is in the proper position before you repeat your manual muscle testing. The scapular stabilizers, we do both assessments as a group by using wall push-ups as an example, but we also like to do single muscle testing for the lower trapezius. We like to test the serratus anterior, and those two muscles in particular, we like to look at them individually with manual muscle testing. How do we take this information for our rehabilitation planning? We correlate this information with forced couple abnormalities, particularly the rotator cuff deltoid and the scapular protractors and retractors. Neurologic examination is part of our complete examination of these patients, particularly in the initial assessment. Certainly looking for neurologic symptoms in some of these patients with numbness, dead arm, but here what I'd like to look is to make sure that they don't have suprascapular neuropathy or some kind of cervical radiculopathy, particularly older players, or plexopathy. Also, we look for symptoms of thoracic outlet syndrome in patients with significant shoulder protraction, shoulder laxity, and scapular dysfunction, both at rest and with activity. Special tests, this is a combination of what we usually do in our clinic. We do pain-producing maneuvers. We start with impingement maneuvers. We always do apprehension testing, looking for the combination, particularly young athletes, of impingement and instability, and we also look the position of apprehension to try to reproduce posterior shoulder pain associated to internal impingement. Okay, so these are the things that we do in the start. We look for slap or labral injuries doing the O'Brien's test, and we look at some of the older patients by reproduction of pain over the acromioclavicular joint. We look for AC joint pathology as well with this test. In terms of testing, as I mentioned, for us it's very important to locate individuals that have multidirectional instability or laxity, those who have acquired instability following shoulder trauma, and those who have multidirectional laxity associated to generalized ligamentous laxity. So we always do provocative testing at least in two directions, if not three directions, so we always do a sulcus test to look for inferior laxity. We always do apprehension maneuvers to look for anterior laxity, and then if these two are positive, we look for posterior laxity by using the load and shift test. For the scapular assessment, we use the lateral slide test that was proposed by Ben Kibler many years ago. We measure the position of the scapula with the arm at side, the arm at the hands of the hips, and at 90 degrees of abduction looking for an asymmetry of 1.5 centimeters over the asymptomatic side, and considering this a positive test. This is a picture of how to do the test. Here we have Jerry Malanga testing one of our attending physicians, Luis Baerga, actually from his physical examination book, looking at the asymmetry of the scapular with dynamic activity, the lateral slide test. We end with doing a very simple kinetic chain evaluation. We may do single leg stance, we may do a double leg stance, activities depending on the sport, and we also do landing from a jump in a single leg to look at athletes that play jumping sports such as volleyball. So those are very simple things that you could do. What do we look for here is we look the alignment of the trunk, make sure they don't have lateral trunk lean. We look the alignment of the knee and the second toe, so we think that if the knee is medial to the second toe up on landing or with a single leg squat, we consider that abnormal and a normal kinetic chain assessment. The principles of rehabilitation are based on what we have found and in this test, physical examination, and history that we've done. We look for optimizing scapular soft tissue mobility in the early stages. We try to look for improvement or shoulder loss of motion, particularly internal rotation and posterior capsule tightness. We look for improvement of scapular muscle strength. I mentioned two key muscles here are the lower trapezius and the trapezius and this serratus anterior, but we also like to test athletes following activity, looking for fatigue and absence of neuromuscular control following repeated activity, and that's that's key in our assessment. We like to restore rotator cuff strength, particularly we look for normal strength in the infraspinatus and external rotators of the shoulder, which we know are very key in shoulder depression with forced couples. We like to correct forced couple abnormalities early on in our rehabilitation program. We look for those once the athlete goes back to activity. We like to retest all these muscles following the start of a sport specific activity to make sure that that the activity doesn't fatigue the muscle and brings back symptomatic symptoms with activity. We normalize core. We have mentioned around in the stocks the importance of the stance leg and the swing leg at different times in the in the overhead throwing motion, softball, also in volleyball, basketball, and other motions are important, but I think in baseball in particular we know that shoulder stance leg gluteal strength and rotator strength is very important, and the swing leg we need to look for rotational flexibility, particularly the external rotators, so we look at both control and flexibility in the stance and swing leg, and we also look for distal lower extremity stability, particularly the last note that the patient doesn't have dynamic pronation with fatiguing activities. After we do this in the clinic, we progress to functional activities involving all components of the kinetic chain in a supervised manner. I think the return to play criteria need to be really defined in this population. A couple of things I'd like to highlight from the management perspective. First, I'd like to highlight that we need to start by stretching the anterior muscles that are inserted in the core cord process. This is key in order to improve the shoulder mobility and improve the reduced secondary impingement because they reduce subacromial space, so in this population in particular with scapular dysfunction, this is key in the early stages of rehabilitation, and the second point I'd like to make is that we need to activate scapular stabilizers early prior to including the whole kinetic chain in the process of rehabilitation. Here we're doing, in the left side of the slide, you see low rows, then we see scapular compression for the depressors of the shoulder, and here we see a combined rotational movement that activates the scapular stabilizers, so initially we should activate these muscles in pain-free motion, recruit them, integrate them into the kinetic chain, and then bring them into functional activities, multi-joint activities, single leg and double leg supported activities, similar to what sport-specific activity requirements are needed for the athlete to perform at a high level. In terms of return to play, and this is something that really needs to develop more in the shoulder upper extremity athlete, here we look for full non-painful range of motion, particularly in sport-specific ranges. We look for normal shoulder strength and scapular control. We are starting to use more of an isokinetic testing to assess the return to play protocols in our institution. We have been doing it for years for the anterior cruciate ligament, so now we have started a more formal process for the shoulder athlete and upper extremity athlete. We are doing functional testing for the lower extremity athletes, and we have started to look at some of the functional tests, such as jumping, single leg control tests that could be applied in our exercise physiology laboratory for return to play in athletes with shoulder injury. We look for shoulder stability, and we understand that some of our patients are going to have multi-directional laxity, and we make sure that this stability is enough for the patient to be able to do their sport-specific activity without symptoms, following fatiguing activity, and following testing. They should complete a throwing program without pain under supervision. They should go back to practice and have no symptoms with practice under the coach's supervision, and here is an important key that we've been doing more and more, looking at this from the perspective of the athlete. We always feel that the athlete needs to feel that he is psychologically ready in order for us to allow them to return to sports. Many times, this gives us the key, because we think that psychological readiness is a proxy for physical readiness, so most of our athletes who feel psychologically ready, when you do the rest of the testing protocol, they do very well. The ones that are not psychologically ready, many times, have some of these imbalances or dysfunctions that we have mentioned, and they're not ready for return to play. So what did we learn today? I'm sorry, this has been a very quick review of some of these important concepts. We know that the scapula is very important in the kinetic chain of the overhead athlete. We know that scapular dysfunction is common. It may precede symptoms in many of these athletes. It could be associated to soft tissue inflexibilities that impact the position of the scapula at rest, muscle weakness, particularly with activity and fatiguing activity, and also neuromuscular or firing deficits that need to be addressed. The history and physical examination in your clinic should be performed in an orderly manner, assessing the history, looking for specific findings that could be associated with laxity or eccentric overload, looking for younger athletes that may have the combination of instability and impingement, and looking for older athletes who may have injuries that may require more advanced testing and or surgical treatment. Rehabilitation should address these dysfunctions, and as clinicians, we should make sure that athletes are ready on a criteria-based progression, a return to play protocol prior to allowing them to going back to activity, not using just time-based criteria. So just to end, this is how we like to look at some of this information. This is a cluster of findings that we see in patients with scapular dysfunction that come to us with pain associated to impingement and instability. So in our exam, we like to document depressed dominant shoulder with scapular winging. We look for tenderness, anterolateral shoulder, subacromial space, but also in the soft tissue generators. We look for shoulder loss of internal rotation, weak cuff, particularly external rotators and scapular stabilizers, provocative maneuvers for impingement and apprehension to help us understand what's happening with the athlete. We look for labral pathology, be that internal impingement or labral slab lesions, and we use the lateral slide test as a proxy of assessing the scapular stability of the shoulder. And here are my references. It was a great pleasure for me to share this information with you guys, and I'll be happy to answer some questions at the end if you have any. Thank you, Dr. Michaud. That was awesome. Many of you may not know, I really started learning about the scapula from Dr. Michaud when I was a resident and then a fellow in my first couple of years. I had the opportunity to speak with him, so he's really mentored me on that aspect of the Kinect chain. So we have about half an hour left, and so we'll be doing questions between each talk. We're actually running on just about right on time, so when we moved right to Dr. Prather, and there was a method to my madness when I had her going last, I had a feeling every single speaker was going to keep including the hip and the low back in everything we talked about for the most part, so now we get to see the expert in lumbar spine and the hip and why this matters in our overhead athletes and so without further ado, Dr. Hathi Prather. Well, thanks. Thanks for having me and thanks a lot for giving me more than one body part and being at the end. I will have more questions and answers. I've done some research and I have an interest in liberal pelvic stuff. This is my first time to give this talk, so bear with me. There will be a lot of data in it, and just know I gave you every single reference with the review that I gave you, so just we'll plow through, and then hopefully at the end, we can all ask each other more questions than I have answers for, so thanks again for having me. Okay, I have one financial disclosure. I'm a senior editor still for the seminar journal and other non-financial disclosures. I kind of just give you my background. Just as everyone's talked about before, where are we coming from and why are we interested in this? I think we have to give accolades to Ben Kibler because he was so active of being a person to observe motion and then saw the injury as a surgeon, and he wasn't that popular when he went around to other disciplines that weren't surgical asking for collaboration and promotion of what do we do with the kinetic chain in our athletes, and so most of us that are older read a lot of his book chapters and saw him speak. This was one of his better, I thought, review articles on it, and then the review article that came out of the now Shirley Ryan Ability Lab was the newer version of that original article and the advances that were made, so again, just tribute to why we're all kind of here and interested in this. I'm going to talk about each part of the phase of baseball simply because we're talking mostly about overhead athlete and because it seems like the best stuff on hip, spine, and lumbar is really still in that literature, so I'm kind of narrowing it to that, so I'll go to each different phase and then talk about just the specifics of that, so the first phase, the trunk phase, what are the trunk and hip duties during that particular phase? So, it's got a balance on one leg and your body is beginning to rotate away from the intended target, and it's intended to store that potential energy before acceleration. That's the whole point of this, and what's needed? Well, we all talked about this hip abduction strength and trail leg. We'll talk about that more. You've got to maintain the athlete's center of gravity of our small base of support, and it's got to be available while standing only on that trail leg, and it helps prevent the downward rotation of the contralateral pelvis, and they also got to have some hip flexion now, and that's variable based on people's wind up, so I've got the muscles in the whole phase here because I have to look at origin insertion to remember their function, and so the function of our gluteus medius and menis and our deep lateral rotators, we talk about the medius a lot, but when the medius isn't working right, the deep lateral rotators, they come in and try to be second string, but the main mechanism, particularly here, is it's getting ready from stabilization into acceleration phase. We also know that Ilios Soas has got a... Dr. Prather, is it possible to switch your slides into the presentation view? I apologize. No worries. Is that better? Perfect. Thank you. Thank you. Where was I? Hang on. So, the Ilios Soas, again, we haven't talked about that a lot today, but you've got to have the available hip flexion to get there. You've got to have the available strength to decelerate as it goes from acceleration into deceleration, and as the first person was talking about, Dr. Pomsky was talking about, oops, that originates in the spine. So, we got to start thinking about that as a muscle, too. I'm going to date myself a little bit, but you're going to have to watch Chris Carpenter here. My former life, I saw Blues Rams and the Cardinals out of St. Louis and spent some time with this gentleman, and he had a pretty horrific arm problem, but he came back and then won the Cy1 Award the year afterward. But looking at his phases here, so early cocking phase is that stride phase, and the gluteus medius of the trail leg is concentrically contracting. It begins to propel the body forward. You have to optimize that stride length in the lead leg, and that leg has been shown to be positively associated with arm velocity. So, again, we've got to have the stride. We've got to have the control to get the velocity. The landing foot's got to go towards hard plate. It rotates a little bit towards third base, and again, we have to have that balance between our adductors and our abductors in order for that to happen. We know the stride length enables the trunk rotation. Again, we've got to have the appropriate length of our hamstring, our glutes, our glute maximus, our hip external rotators, and again, that psoas muscle. Trunk muscles are contracting during this rotation. Contralaterally, the external oblique rectus abdominis and varmortifides are contracting, and ipsilaterally, the latissimus dorsi, internal oblique, and transverse abdominis. This is a pretty precise thing, right? So, we have a little problem in any one of those. We're going to have issues, and one thing we haven't talked too much about today is the nervous system really directs our muscles on what to do, and whether it's the peripheral nerve that's being pulled by the brain to do that versus the central nervous system that helps us control overall resting muscle tone and the interaction between proprioception. So, again, the column in our spine, again, that neural control is really important because our spine is kind of being used as a strut for stabilization in one position and going to end range flexion in another in a rapid motion. I'm also going to just mention the thoracolumbar fascia, and I know in the sports world that sometimes might be a bad world. In some worlds, it's just a bad thing to say fascia, but it's really important for this, right, because our thoracolumbar fascia has a key role in core stability, and I always end up mentioning Bleming's work on the superficial fascia, thoracolumbar region. It's really the connection between the leg bone is connected to the arm bone as it crosses from the hamstring region over into the arm through the superficial fascia. Also, recognizing our fascia in 30% of people is directly attenuated or connects to the hamstring, so, again, understanding not only just muscling and firing but tissue activation and tissue movement, I think, is really key. Again, this thoracolumbar fascia is really key in decreasing shear forces of the three-joint complex across the spine, and then it has a shear force absorption across the pelvis, so I like these pictures because it gets all complicated to me if I have to separate them, so I gave them to you. I like these colors. They're kind of cool, but the real thing is this is a tube, right? It's a cylindrical tube, and this activation we talk about intrinsic or contralateral and ipsilateral contraction. There's this tube effect, and, again, the fascia around it and the muscle have to play the role of a strut but also have to be able to fall into motion rapidly, as we're going to talk about in the next phases, so, again, the gluteus medius and minimus and our deep lateral rotators this time, again, they're accelerating through hip abduction as the pelvis is starting to move in a forward function, and our iliopsoas is decelerating the anterior rotation of the pelvis as it accelerates into hip flexion. We know our adductor magnus and longus at this time have to help with the deceleration of flexion and internal rotation as we start to go towards the ground, so in that late cocking phase, which is supposed to be the end of external rotation of the shoulder as it's going towards release of the ball, we know the abdominal obliques eccentrically contract to prevent lumbar hyperextension, and we know the trail foot from the rear foot to the forefoot and weight propels it forward, so, in other words, the shift weight shifts. Contraction and length of the hip extensors is really important at this phase, and length of the hip flexor obviously is important. I would also say probably position of the hip, right? You can see Chris Carpenter up here in his Cardinals uniform. He's got some internal rotation going on in his hip versus this Mets player has less of that, and so probably there's some correlations there as well that I don't really see that much in the literature. During the acceleration phase, again, we're trying to get to that ball release stage. The stride length accelerates into hip flexion. The lead foot should contact the ground. The toes are pointed towards the intended target. Both hips have to rotate, right, and one's going in one direction, one's going in the opposite. Trail leg must internally rotate properly to the lead leg to externally rotate towards the target. This allows the trunk to rotate towards the target and throwing on to follow. Hip rotation is the key, particularly. At the spine level in the posterior pelvis, it's got to act like a strut so we don't get this whipping motion from extreme extension going into stream flexion, so I would argue that that's probably a component that's necessary at that time, too, and then the deceleration phase, again, when the ball is left at hand, the stride leg continues into hip flexion. You can see his hips here are both internally rotated slightly, and then the contralateral internal rotation torque, the forces must be dissipated, again, throughout the trunk. During the follow-through at the end, the trunk continues to decelerate. The side leg stabilizes and absorbs the forces, and the lumbar flexion is needed to help absorb and dissipate the forces. It's actually in parts of the phases of rotation where a lot of the trunk, particularly the lumbar spine issues, seem to be particularly affected. There's all this focus on the gluteus medius, and I would argue we should probably contribute everybody who's a hip abductor being important here. Our basic understandings in the beginning came from studies like out of the Burkhart study showed 44% of people with a slap injury also presented with gluteus medius weakness, and they noted this by a positive Trendelenburg, and hopefully those of us in physiatry will notice it prior to the Trendelenburg actually happening because we can hopefully test the gluteus medius in multiple planes and not just rely on a single leg stance. The pictures have been shown to have less gluteus medius strength in the trail leg compared to the position players, so again, identifying gluteus medius weakness and comparing it to the opposite limb may help reduce upper extreme injuries, and that's where this all started is noticing these relationships between what's happening in the trunk and the core and what happened, and that's where the interest started. This is back from 2010. This is again from Gretchen Oliver's work, and I'm going to show you two of her studies, and these were both in high school athletes, but she was using EMG, and she was trying to really assess the motion through the pelvis and torso, so taking that what we know associated with an injury and trying to put it into lab and make sense of it. I personally plant for a living myself, and if you sit down with any of her papers, you'll need some steak sauce because they're pretty meaty, and getting through them is really interesting, but what she looked at in this study with high school pitchers and she had them do fastball pitches, she looked at the actions of the shoulder strongly related to the action of the pelvis and torso throughout the pitching motion, so we treat them as two body parts, but accumulated today, we've talked a lot about their interrelationship, and only the rate of the axial torso rotation was significantly related to these shoulder movements, so it was the rate at which this motion happened which has to, there's got to be this cumulative load and force that stabilizes while muscles are activating throughout the thoracolumbar region. This help may explain the high rate of shoulder injury in high school players, and the conclusion was strength training should focus on developing a stable core, including gluteal musculature, and attempt to control the rate of torso rotation during the pitch, because if that spine and that fascia there can't help work as a strut, we're going to see breakdown. This was also published in the same version or same article in the same timing of the last one, which is impressive because it's hard to get dual publications in the same journal at the same time, but again, same group of high school athletes doing a fast pitch, and she looked at their gluteal muscle activation and their relationships to the pelvis and torso kinematics throughout the high school pitching motion, and for all the pitchers that she looked at, their preferred gluteus maximus activity was observed to be in excess of 100% of their maximum voluntary contraction throughout the stride of arm cocking phases in pitch and meet. It was on, and they were using it at its highest level if they tested it in an isolated position prior to putting the EMG testaments on them, so from the conclusion of the stride phase to the conclusion of the arm cocking phase, the muscle activity increased for all pitchers. Because the pitching motion progresses sequentially, meaning it goes from one thing to another, and that's got to be in this coordinated sequence fashion, the variability in pelvic rotation may be directly related to the variability in torso rotation. To me, this is so key because that's exactly what we see all day in clinic. Everybody's got a different variability of the way their pelvis moves. I've asked my research mentor, Melinda Van Dylen, who studied a lot on level pelvic motion. I said, well, how much is too much motion of the pelvis in a transfer plane and ambulation? She says, four degrees. I said, well, how do I measure that in clinic? She goes, I have no idea, so again, it's those things that we observe that we know are meaningful, but how to measure them directly, so I thought this was really wonderful, so during the baseball pitch, her conclusion was that there's no greater control of gluteal activation through the pitching motion, so we really need to have our gluteal muscles working in order for this to work right. Now, this is the third article from her lab, and you can see how she's advanced in technology. She's using an electromagnetic tracking system that uses collective kinematic data while participants perform these jumps, and this is a national handball team, and so now she's adding people that are jumping off the ground, and she examined them for lumbopelvic complex stability using this knee valgus measurement and affecting throwing kinematics during the handball shot, so these people are actually leaping up, so they're leaving the ground as they're watching it, and again, she saw these significant differences were found between pelvis, trunk, and humerus and forearm based on how they landed, and again, specifically the unstable group displayed significantly slower speed, so we know this chain reaction is directly related to performance, but it's most likely also related to instability and injury, so again, the advancements from Dr. Kibler showing us what he's observed and studied in his lab and just the technology in this one investigator's ability to study this motion in just what under a 10-year time is really phenomenal, so I think there's more good information to come from this, so I'm going to go through about just the hip itself, so the hip internal rotation, again, it really needs to be there for there to be optimal synchronicity in this chain, so baseball pitchers tend to have more hip internal rotation in the trail leg than those of positional players. Pitchers tend to have less internal rotation of the trail leg than position players, resulting in a less effective potential and more dangerous throwing motion potentially, and then there's direct association between increased hip rotation of motion and your increased ball velocity, so obviously, people want to chase that. If my hip internal rotation is good, my velocity is better, and again, something important to look at. Now, I've rearranged that by looking at hip external rotation, and again, that lead leg needs enough hip external rotation to position the lead foot in the right place. Again, we have to have this certain position between midline so that we can go ahead and hit the target. Again, that alignment is really important. If there's too much external rotation, and defined too much is hard to define, the pelvis will rotate and leading to this decreased control of motion of the pelvis itself. If there's not enough hip external rotation, it will also cause the lead leg to be positioned too close to the midline of the body, and you'll see that crossover, so inefficiency. A variant hip rotation will lead to disruption of the kinetic chain, ultimately loss of energy production, possibly an increased amount of force placed at the shoulder and elbow, and again, that association with injury, so again, looking at hip rotation in pre-season and prior to return to sport, especially after an upper tributary injury is really important, and again, assessing this in multiple planes is key. Other things looking at total hip extension and total arc of motion, I've now kind of advanced from there, so this one's of 57 baseball athletes and the relationship between their dominant extension and shoulder external rotation was significant for pitchers and non-pitchers with shoulder injuries. Looking at also a passive range of motion is smaller or less in the non-dominant hip than the dominant hip in professional pitchers. Again, this disparity between the hips is significantly correlated with various pitching biomechanical parameters around the trunk and pelvis. Again, so we're getting more advanced at looking at just one motion, but how this combination of motions are important in the hip, and this is from the Japanese literature looking at young athletes, so these are like 9- to 12-year-old baseball players, and they looked at 210 of them at a national tournament, and 9% of them had elbow and shoulder injury during that tournament, and they saw a significant restriction in hip internal rotation of the stride leg compared to those without pain. In another study by the same group looking at over 2200 overhead athletes, again young kids, they found there was a higher prevalence of elbow or shoulder pain in those that had other body part pains, particularly downstream, including back, hip, and knee, and even foot, so again they proposed these links again between what happens at the arm may actually be symptomatic from what's happening below at the trunk level. We know this is looking at softball range of motion, hip asymmetries again, and trends of course over time, this was mentioned previously, that we'll see this decreased range of motion, increasing the shoulder and decreasing the hip, it actually can lose strength over time, so in the pre-season look at the mobility, the dominant shoulder pitchers increase, and over the season again that strength and the non-dominant side might be lessened, so looking at what we do pre-season and what do we need to do to maintain that during the season and what is fatigue and what's improper mechanics over time, trying to get that ball from one place to the other is probably a dual thing that needs to happen for injury prevention. So now we get to the part where, okay so I wrote all that, that's all the baseball stuff and a little bit of some softball, showed you what they're electronically, you know that what's happening in labs and we're going to get better information, but how you guys, wait a minute, we talked a lot about hip range of motion, there's a lot of things to hip range of motion, so if we look at the bony contact first, I mean if you've got an underlying hip deformity, you may have, that may ultimately start at your base of why you do or do not have great hip motion or excessive motion, so we know folks with femorizational impingement often have reduced flexion and internal rotation. What is reduced? That is really always the question. In the surgical world, under 20 degrees of hip internal rotation with hip flexed at 90 is kind of the cutoff from a surgical perspective, but if you look at our hip range of motion studies, they're all over the place as far as how they were done in large populations, and there's always a range, and is that range related to underlying bony deformity, and those are kind of the big questions that are out there. Also, if you have ascitabulary hip dysplasia, you often can have greater range of motion. A lot of folks have a soft tissue or connected tissue. Lots of flexibility goes with that, and they often demonstrate poor motor control, so is that why, when we get into the professional level of many sports, that the incidence of femoral ascitabular impingement is actually quite high? There's a Japanese study that came out in the last year and a half that showed 76% of baseball players in Japan had femoral ascitabular impingement, and is that because you can use the strut of the pelvis, of the bony pelvis, as a stabilizer to help improve motor control because you have less range of motion control? Questions I have, answers I don't have, but if you look at preparing for this talk, I'll go back and look at how did we come to have the FAI overhead athlete? What you'll find is many studies, I counted 40 of them in my first look, of return to sport and how well they did after surgery, so as usual, we've gotten the cart in front of the horse as far as why did it happen and what should we be doing about it versus if we do surgery on it, they all do well, which is great. We want people to be great, but we've still got this lack of information about this disorder. Measuring in the future, so what do we know about looking at people with this hip morphology and trying to take measures in terms of this? This is out of Ashish Bedi's work. He's just the middle author on this paper, but I got to meet Ashish when he first got this suit and got to put it on. It's really interesting. This is 11 collegiate pictures that he had put on this full-body inertial-based motion capture system, pretty cool stuff, and did some CT modeling of their hips, did passive range of motion of their hips, and wanted to see what's going on at the hip level when they have this sensory mechanism on the two that measure it, and so the findings, again, hip flexion was the only passive range of motion measurement showing a significant difference between the lead and the trail legs, and during the hip pitching motion, within individual differences were discovered between all of these things, flexion, extension, abduction, abduction, external rotation, and total arc of rotation, which means probably soft tissue-wise they develop these imbalances because of repetitive patterning. There were no significant differences in morphological measures between the leg and the trail hips, which is pretty consistent with the hip deformity literature, right? A lot of people have deformity bilaterally, but they're only symptomatic on one side. No one's got that one figured out completely yet either, so that fits with what we know, and then they did this dynamic CT modeling, and what they showed, it really didn't show true bony impingement in any of these folks, but what they did show is that these people really utilized and went to the end range of motion in their hips when they were going through this fastball motion, and there were no differences found in passive hip range of motion or morphology other than small differences in passive hip flexion, okay, so we talked about that at the very beginning that the flexion piece is really important. Again, hip dysmorphology, or I mean deformity, or poor pitching mechanics also may lead to a high risk of bony impingement because pitchers have very little reserve hip motion during the fastball pitch, so meaning they're using it from one extreme to another, and people with less motion in the beginning may be at more risk of developing injuries, so what's missing out of this baseball stuff that I rapidly put myself through to try to put this talk together? A lot to me. I have more questions than answers, as we talked about before. We see that the spine is really asked primarily to go from a stabilizing strut to end range flexion and decelerate without a hitch, and a lot of that is dependent on activation of the muscles of the trunk, our obliques, our abdominals, or even our multifidies, but it's also dependent on that soft tissue, the fascial strut of the stabilization plane, too. We also know if we got to go from an upright position in the spine to an immediate end range flexion, a lot of that's depending on our mobility of our hip, and again, where does the fascial plane and joint mechanics of that play in the role of the spine's ability to go through that rotation? The other big mystery to me is this pelvic thing, and I, too, am an osteopath, and we know that that pelvis theoretically can sit in 56 different patterns, and this stuff's really hard to move, and so people have all kinds of different movement patterns they come to, which we interpret as posture, and the position of their ilium in a sagittal plane has a lot to do with how they activate the muscles of their core and their trunk, and so to me, these are still kind of the missing holes as far as the overhead athlete that we still have a lot to learn about in the future, so the take-home messages are upper extremity injuries may be the victim of poor lumbopelvic and hip stability. The tail is wagging the dog, right, because if the pelvis and the hip and the spine cannot do its function in a normal way, we're really going to have problems in the upper extremity. The lumbopelvic hip motion control and strength is very important, and we need to learn to train and modify based on hip range of motion, flexibility, and strength, and flexibility, I'm just talking about that. When Dr. Holtz was talking about that she uses dry needling a lot, I was happy to hear that because dry needling and things that we can do to decrease resting tone of muscle really helps us separate between when a muscle is truly short and when a muscle is on and doesn't know how to stop, it doesn't know how to relax, doesn't know how to then go back to that proper actinomyosin length difference that really makes a difference in how well it's utilized, so I think there's all kinds of interesting things around that. I have a plug for fascia, really important to use it as a strut in people with connective tissue or don't seem to have normal gliding of tissue. Looking at that as an intervention model can also be really helpful, and then the last thing would be looking at how the hip moves in a passive and active way, whether they are somebody whose hip stays modified and does well with gliding in motion, just like you look at a shoulder or not. Hips have the same sort of problems with posterior capsular stiffness at times too, again not as well described in the literature, so thanks again for having me and being at the end. Sorry that was rapid, and the references are all in the talk that you'll be giving. Thanks. Thank you, Dr. Prather, and for everyone, I am with my watch, and we are exactly at 1 p.m. Central, 2 p.m. Eastern. We literally finished within 30 seconds, so great job by all the speakers. I think we did some of the Q&A in between each talk that helped. I'm sure we need to take another question or two. We could probably do that. I think there was only one other question in the chat that Dr. Michaud answered via the chat, but does anyone ever have any other questions right now before we hopefully enjoy our Saturdays? Well, again, thank you, everyone, all of our speakers, all of our attendees as well, Dr. Cianca for helping lead this initiative, and to Brian Thompson in the background and the Academy for setting this up. Be on the lookout for another spotlight series in a couple of months from now. I believe they're going to be looking to do possibly the lumbar, spine, and lower extremity mechanic change perspective. If you have any feedback, by all means, please let any or all of us know to continue to improve this series, and for Dr. Cianca as he can choose to grow it as well. With that, everyone stay safe, enjoy the rest of the weekend, whatever part of the continent you're in right now, and thank you so much. Thank you for the invitation. Great session, guys. Thank you. Thank you, everyone.

kinetic chain

pitching mechanics

softball

legs

trunk

scapula

upper extremities

force generation

hip strength

scapular strength

assessment tools

scapular dysfunctions

scapular mobility

scapular stability

shoulder injuries