Changing the Freestyle Paradigm- What High Speed Video Analysis Tells Us About Freestyle Technique by Dr. Jan Prins (2011)


Published


Introduction: I would like to introduce myself, my name is Mary Ann Gurzanick-Liebowitz. I am on the ASCA Board and I’m the Assistant Coach at Oregon State University. I have the privilege this afternoon of introducing to you Dr. Prins and I would just like to go over a few things that I think would be interesting for you to know. He is the Founder and the Director of the Aquatic Research Lab at the University of Hawaii. He has served at the faculty there at the Department of Kinesiology and Rehabilitation Services. He was Doc Councilman’s Head Assistant Coach at Indiana from 1975 to 1978. He…close this a little so I can see…For the past 20 years, his research and interest have been combined with competitive swimming and aquatic rehab which he calls Prins Aquatherapy. His recent article in the American Swimming includes Biomechanical examination of the…again, the glasses…can’t even read my own hand writing. This is very, very disappointing. Well, in any event, we’re going to talk about the front, the arm stroke or the freestyle and the angle of it as well as the body roll. So please help me in welcoming Dr. Prins.

Dr. Prins: Thanks Mary Ann! How many of you were here at one o’clock? Okay, I figured most of you were here. So my original thing since it was yesterday was a prelude to what I talked about this morning or this afternoon so I thought we’ll just whip through the stuff that I talked about earlier because it is a lot of the intro things and then I will add on more.

As Bob and Steve said, I can go through quickly and then we can slow down when needed but it’s not a bad thing to repeat ourselves sometimes. I’m still trying to figure out what I’m talking about. Okay here…Now, we have to be out of here by 5 so we can take questions or continue out there because they have to set this place up, this is part of the banquet. Okay great, so I’m going to like, as I said, let’s move along fast here. This quote I don’t need to spend time on. Where are we? There we go. You’re going to see a lot of repeats, this is what we’re going to talk about and the picture I started off with talks about Biomechanics and Biomechanics is the use of Anatomy and Physics to look at motion; that’s how we define Biomechanics.

The stuff we’re interested in is all based on video and I was starting off by telling people, when you film a regular video that’s 30 frames a second which is three one hundredths of a second. Of sixty fields, people are marketing these cameras now and claiming it to be high speed but it isn’t because all they’re doing is opening and closing the shutter a little faster. This is the important thing: Shutter speed and frame rate. What you’re paying big bucks for is frame rate and the cameras that we use can go up to about 200 frames per second and we chose a hundred frames per second because anymore than that is overkill for us right now so I’m going to show you the little clip here to give you an idea what a hundred frames per second looks like in real speed here and I’m going to scrub forward here. Let me move this so I can use my mouse a little more deftly than earlier, but I never get tired of watching this.

This is a hundred frames per second so instead of three one hundredths of a second, we’re working three and a half times as fast and that’s why it looks three and a half times as slow but you can see how clear everything is. We don’t drop any frames because the 30 frames per second things look a little blurry at the end. We use multiple cameras. Four cameras is what we’re looking at right now, and here’s the picture of the frontal view, we are facing ourselves out of the above water because we’re not getting what we’re really looking for. It’s not worth…and so we’ve taken both cameras and put them now underneath.

This is our latest invention here, we’re going to start looking at push-offs off the wall, so when the swimmer drives off the wall, this has got to be facing the swimmer and then we have the cameras from the side and these are the cameras so we now have swimmers swimming off the wall, picked up by the camera that you saw earlier, and we can tell whether the push-off’s efficient, we can see variations in body positions and all those things. The foot camera is going to be pointing straight up and I’ll show you videos of what we can come up with that. Remember, for analysis we cannot move the camera. The camera has to be both steady because of calibration. There has to be some way for the software to interpret real distances like meters into pixels and so no moving…and so the mountings are all bolted to the deck.

This is a picture showing how rigid these frames are, and if they’re shooting at high speed they really have to be rigid. Once we’re done filming, we get out and we start doing some analysis using the software and one of the things with the software is that in order to digitize, because we have so many frames, we’re ending up with about 45,000 frames for each subject for one test. We need automatic digitizing. Now automatic digitizing entails somehow another identifying the joint segments. On land, these illuminated little balls; the light flashes from the camera, from these infrared lights, bounces back, goes into the lens, and then is interpreted. Now, we don’t have the luxury of doing that. You can see they even do that on big animals. In the water we don’t have the luxury of doing that because the light would be distorted so we had to go ahead and design these Light Emitting Diodes which look like this…I don’t know why we’re going so fast here. And so you can see, we have to tape it to the swimmers and then the effect we get will give us what we’re looking for. I’m going to go a little bit faster with this because it’s just the way we analyze. So we put it into the computer and we do the analysis and we end up…

What we’re really looking for is what we call Kinematic data which is a big fancy word for saying we’re interested in displacements, angles, velocities, accelerations. Those are the things that we’re looking at. Now some people talk to me and ask me how come we’re not measuring forces? That is a different part of Biomechanics and in the water it gets extremely complicated. Forces, you have to have sensors, nobody has really figured out how to pick those sensors up really accurately but when you come to look at it, we’re just interested in how much the hips are displaced, and so I’m going to show you some reports that the software can generate and the software is very good because it can generate…again I’m trying to go through frame by frame and this thing is jumping so bear with me.

The report…this is what you get for $16,000. Interfacing a video with the graphs, so it’s very, very valuable. I’ll show you a real report in a minute but I wanted to show you a still picture first so you can see what’s happening. We can film the swimmer and as the swimmer moves across, you’re going to see the vertical bar, this vertical bar right here travelling, synchronizing every single part that we see in the video matched with what the swimmer’s doing.

Now, Steve and Bob from based on the earlier lecture asked me to give you a little bit of feedback on what you see here and clarify some things. Up here is hip velocity which is the bottom line. That’s what we are paid to do, change hip velocity. But we also have hand velocity here that’s being tracked at the same time but I want to clarify something, the fact that this is going below the X axis has nothing to do with going slow. By convention in Biomechanics, things going from left to right are positive, and right to left are negative and so when the swimmer’s pulling his hand, the hand is going from right to left and that’s why it’s dipping here below the zero so that’s the only reason and I’ll show you as I play the video.

I’ve highlighted this in red because I want to make a point. As I said, hip velocity is everything, that’s what we’re paid to do, increase hip velocity. What you do with your arms, and your feet and all that, we can use this big fancy term, cyclic translations and rotations. Translation is simply a linear movement and a rotation of course we can all relate to. The studies that we’re doing currently are Freestyle and that’s what we started with, and we started with the most simple things I thought we can track first. Bent arms, straight arms, dropped elbow, and the S-pull. And this was presented last year at Oslo at the Biomechanics Conference.
First of all let’s look at Bent arm versus Straight arm. First thing is, we don’t swim. Elite swimmers regardless of what they think they’re doing are instinctively picking an obtuse angle. Ninety degrees obviously isn’t working and we’re going to make a case for it. Those of you who have been here earlier will appreciate what I’m going to say and those of you who haven’t, I’m going to make a case for why a little bit straighter arm works better. Now, the corresponding finding was that the peak hip velocity takes place not at the end of the stroke, and this is what…I can’t think of anybody who didn’t think that the final thrust of the hands was not the part that moved the body fastest through. And then you’re going to see in a minute that that is certainly not the case so I’m going to play this video clip and you’ll see what the report can generate and I will go slowly first but here’s what the report does, it plays and I’ll scrub this until we see the swimmer, and you’ll see the hand coming through and you’ll see this vertical bar and remember we’re looking at hip velocity and hand velocity so here comes the swimmer. Notice now we are tracking the hip and the hand, the right hand. I can watch this picture over and over again and get something out of it, but notice how the vertical bar goes across and the peak velocity is right and let me scrub back, in the middle third of the stroke. It is not at the end and why that’s the case we will talk about it in a second.

The debate is still a little bit open in terms of the people I’ve talked to as to why the peak hand velocity is a little bit before the peak hip velocity. I think it’s because you have to first to get your hand holding the water and moving your body before the body actually moves but again, between Bob and Steve, we had been chatting about this but we’ll see, with more swimmers we work on, the better we’ll get an idea. Now here’s a freeze frame of what we just saw and I stopped it again right where the peak velocity is. It is clearly in the middle of the stroke. If you have questions later we can chat about this but this is what we saw, we didn’t come up, we didn’t invent this stuff.
So what is the ninety degreeable bend? Why did we, for the last 50 years talk about ninety degrees? Well, the reason for that is because when we bend our arms neuromuscularly, the signal is that at the maximum torque is generated when we bend our elbows at about ninety degrees and that is because it’s a fixed resistance. If I give you a heavy box, you’re instinctively going to stick your arms out and bend it about ninety degrees, that is because we are trying to reduce the external torque. We don’t stick our arms out because the external torque goes up because of the force arm, so we minimize the external torque by bending our elbows. So why then are we talking about straightening the arm and getting more bang for the buck when we’re swimming? Short answer: water is not a fixed resistance. That is it. There’s no other way around it.

Here’s a more detailed explanation and as I said those of you who were here earlier, hang with me. For the people who weren’t, we use propulsive drag forces to move through the water. That’s the primary form of propulsion in the water. Drag forces…a formula for drag force whether it’s slowing us down or speeding us up looks a little complicated. But what for us, there’re two things we can manipulate. The two things are the area, the cross-sectional area – a bigger hand of course can generate more propulsion force but for us, this is the key right here, the velocity. And why it is a key is because the further away our hands are from the axis of rotation, the higher the velocity.

Here is a good example of what that is all about. Baseball hitting, kicking, think about tennis serve, golf swing, whatever you’re looking at, if we maximize the radius of rotation, we would get the highest velocity and that is the reason that we are now able to swim faster with a higher velocity and this is the reason that good swimmers regardless of what they’ve been told are swimming with more of an obtuse angle. I’d mention earlier too that Doc constantly kept reminding us that swimmers swim fast in spite of their coaches. There are pictures of Spitz and Top all swimming with ninety degrees but I’ll bet that if you ask them to play around with their stroke they’re going to do it a little differently just like most of the swimmers now. So does this mean we should swim with the fully extended elbow? No. and I’ve put the slide’s delay while dealing with talk at the end of the lecture today so I’m going to go a little fast with this and then we’ll get to why this isn’t working.

Now, it does work, the straighter arm, because as I said the linear velocity is higher. This is an ultra-sensitive…okay, so the linear velocity is higher and there’s the further advantage of course, with a straighter arm, you’re travelling, if you look at the trajectory, you’re travelling a further distance so you can apply the force a longer period of time and that’s why the distance per stroke of course goes up because you’re applying a force for a longer period of time. Why aren’t we bending our elbows to ninety degrees? Because of the shorter trajectory. At a shorter angular distance, a shorter trajectory means your arm is going to go slower and then we all know this, if you move your arms in a more linear fashion, it’s going to get the water moving and you’ll have less resistance or as I said I found the funkiest looking paddle steamer. Each of these vanes are going to grab some water and get out of the wave so that the next wind can grab the next fresh non-moving entity. This is not what we would do in the water. This works on land but that is because it is a fixed position. We go back, okay, this is all fixed. This does not work in the water and the story again, I’ve never tired of repeating about the guy who got all the investors in St. Louis and made a paddle steamer that looked like this and they all went down on the deck the grand opening day and the steamer didn’t move because of course you’d had no purchase on the water. Once the winds grabbed the water, the mass action awarded to Goran [phonetic] [0:19:02] and he headed out of town I guess. [laughter]

So much for the straight arm. Two of the other things we worked on of course was the dropped elbow and we asked the subjects to purposely drop the elbows and I’m going to show you the next report and we’ll play this, I’ll go a little slower this time, the earlier group. I thought we were hurting for time so I whipped through it but I’m going to play this for you and you will see a very predictable outcome and now you can see we can interface head-on and a side-view as well. Here’s the hip velocity over here, and you know what’s going to happen. As he comes up here and starts dropping his elbow, and let me stop it right here. Here’s the dropped elbow coming up, can you see this? Look at the hip velocity starting to plummet. But also interestingly is the hand velocity. Can you see how high the hand velocity is? In that way we will know, we know that the velocity when you’re slipping over your hand is going to go crazy. So here is a still picture of that with some numbers and you can tell the difference. There’s a huge difference in the hand velocity when you have dropped elbows versus a regular bow [phonetic] [0:20:29].

Next thing is the S-Pull. Infamous S-Pull. I equate it with the nine-headed hydra, it never dies. [laughter]. Somebody is going to publish the S-Pull somewhere and I hope…I’m on a quest to kill this thing but it never does. The misinterpretation is because we are trying to figure out in 2 dimensions what is actually taking place in 3 dimensions, that is the big problem and you can’t do that. So I’m going to show you Park in Beijing winning the 400 Freestyle, cameras in the water, underneath travelling with him. But no matter, we’re interested in the path. So watch what’s happening here. When we put the trails on, that’s what it looks like but that’s not what he does. He’s not swinging his arms around back and forth like this. So here’s a still picture from what I just showed you. He is in no way doing this swinging back and forth. I always have fun with some of the swimmers and say, let’s count our strokes and just do this crazy S-Pull stuff and they start laughing and say no we don’t want to do it. But you can see it’s a three-dimensional movement that’s very sophisticated, that’s trying to be dumbed down to two dimensions and that’s where we’ve fallen into the trap for years and years.

So I’m going to show you another report from our high speed study and this is pretty neat because you’re going to see a very subtle S-pull, this goes on the UH Team division one swimmer and you can see what happens, and here we are, this is just plain old hip velocity, I wanted to keep it real simple, here she comes. Again, I will hand scrub but you can see what happens when you start to veer to the side. Okay so here we are, coming up and now watch. Right here, she’s crossing over a little bit but watch as she starts to head to the side. I’m going too fast here, let me scrub slowly here. Can you see what’s happening? Her hip velocity is starting to drop and right about here, you see where her hand is? It’s gone out to the side. Now it comes back up, she kind of gets back to where she’s supposed to be, underneath her body and you can see how the hip velocity has come up and then again as she starts to go and get her hand out of the way, her hip’s velocity drops again, you see that, right there? Because she’s trying to get out of the way. So all this swinging back and forth does not work, this is a very straight forward view of what goes on when you’re swinging your arms around, back and forth. So I’m making a quick summary here of the points. Obtuse angle of course we all know, and then the middle third I think is something that we know can realize and then of course the S-pull. Forget it! Kill it every time you hear it.

I’m going to show you again and I was asked to show a couple of people and they really enjoyed this. If you haven’t seen it before I think you’re going to be interested. If you’ve seen it before this is a way…it took me about two and a half years to figure out how to do this, but we can interface these trails and what we call trails and segments on actual moving video. It’s easier to do it on still video frames but with moving video it’s kind of fun and I think it’s a very powerful teaching tool so what I did was, use some examples in the different strokes and here is Kelly Stubbins. The Australian National Team swimmers trained with us before they went to the PanPacs last year. Kelly is one of their…I think she’s on the 800 relay team and here’re the trails with her and you can see what we mean by trails. We color-coded the right and left ends and you can see a very nice, early vertical forearm. You can also see her holding her…you can also see how fairly symmetrical her pull is which is something that we can talk about in a little bit. I threw this in because I’ve got quite a few examples of this and we can use this as a training tool. It’s what happens when you don’t do that. And so the trails are very illustrative of what happens when you’re pulling too far across so it’s good because the kids can see what the differences are.

Now we go to Kelly from the side. This is trails again and here’s a good time to look at the deeper pool and notice how the trajectory is a longer time. She can spend longer times with her hands in that trajectory as we just talked about with the straighter arm so it definitely behooves us to go a little bit further down and which is what we do instinctively. We also color-coded the elbows and the hands and I’ll isolate that in a second.

These are the segments. We call them segments because we have identified the joint centers and connected the joint centers with the segment. And this is her and you can see, I’ll go again, let’s stop this and I’ll hand scrub and you can see when she starts, nice, long extended look and then I’ll play this here so you can see the results of an actual moving video with the segments on. So you can see, there’s a lot of things in terms of teaching visually that this is a very nice way to show what’s going on.
Here she is, we added one more twist to this and that is we put a grid, we interfaced a grid to the segments which makes it even clearer when we show people what they’re doing and you see with the grid we can really see how well they lined up. Let me stop the grid here, so you see that? We can really equate…we wanted to put the grid…usually we’re going to line the rig in the center of the body but there was no room because she went down a little bit further. But still, we are going to calibrate this, make it one meter so we have half a meter on each side and so it‘ll be a very good way to show kids what they are doing.

Next is Backstroke. We’re going to show some…oh no excuse me, I just want to show you a little bit of what we can use these for with elbow versus a dropped elbow and show these are the trails, color-coding the elbow and the shoulders and this is a nice high elbow and you can see how little the elbow moves at the beginning of the stroke. See that? And that’s what a high elbow entails. The elbow stays stationary and here’s a still picture that I showed you, a good way to talk about high elbow is to talk in terms of the fact that the hand travels disproportionately to the elbow in the first third of the stroke that’s what we can get out of a high elbow. That’s one way I think we can describe a high elbow.

Here’s what I would call a neutral elbow where you would see both the elbow and the hand tracing fairly parallel paths. And that’s when the elbow and the hand travel at the same time and we see a lot of that. And then here’s what we lie in bed losing sleep over, and that again in terms of a descriptive term, the elbow is going to travel a heck of a lot more than the hand, right there. That is the parallel elbow and this one is the dropped elbow, right here. As you can see, the elbow takes off merrily and the hand is playing catch up. So again, it’s a good way to visually demonstrate what’s going on.

Backstroke, we show you frontal view of the trails first. I hope I’m not boring you folks who’ve been putting up with me an hour before but this is fun to watch. And those of you who haven’t seen this I think you’ll be tickled here to see what’s going on. This is Sophie , I think the one who won the 50 Backstroke at the PanPacs last year from Australia. You can see asymmetry between her right and left hands, you see that? And what I didn’t talk about earlier is the fact that there is a huge difference in her follow through between one hand and the other. Now since we’re talking about interference drag, and I’ll talk about that for those who weren’t here, there is really something we’re going to start looking at is the interference drag of whether you want to get out, let me go back here with the right hand. With the right hand she’s going typically very close to her hips, can you see that? You know left, she’s getting the heck out of there so we have to decide whether that is what we want because I was looking and I wish I had some footage of Ryan Lochte, he does not hang around when he finishes, he gets out of there and that’s quite a gap between his hips and his hands as he exits so if we can put some trails on that, it’d be really fun to see what he’s up to. I really intuitively feel that interference drag is something and we’re going to start looking at pictures of it in a second.

So here’s Sophie with the segments on and in some of these you’ll get more out of the trails than the segments and vice versa but you can certainly put a grid on, talk about the different elbow positions, how much bend in the elbow, how deep they’re going and all that stuff if you put a grid on and look at the segments. So that’s something that we got out of both types of enhancements. Here’s from the side and Sophie really looks nice from the side here with the segments on. You can see how straight she is, see the grid really tells us how straight in line with the segment. She’s at a slight angle, can you see? She’s lying at a slight angle like this which again is good, we can really show that. See right here, you see how she goes down? Maybe her feet are dropping a little bit deep, so it’s easier to tell when you have this kind of look.

And this is one of the swimmers in the University team, and boy, I put this in because he had no idea how deep he was going in into his caption. Holy smokes, you can see his follow through also. His follow through is almost as deep as his entry. Look at this, look at this follow through here, holy smokes! So we could really show them what they’re doing and what they should not be doing.

Next we’ll get to breaststroke and Liesel was one of the swimmers there with us last summer and she was great because it really shows world class swimming. Here’s how the trails with her approaching the camera and you can see how symmetrical she is with both hands. Now there is a slight asymmetry and we were talking about this which I will then, at her level maybe that would make a difference, okay? With a kid who’s just starting out, we’ll take it, but with Liesel? There’s a slight difference and Bob pointed out that he said dexterity, the dexterous side and the non-dexterous side will show differences no matter who you are. But you can tell. See with Liesel, can you see this little…there’s a little difference in her left hand to her right hand. Now, I don’t know whether she’s right or left handed but we can tell very clearly with the grid that there is a difference, particularly the way she brings her hands in. Remember she’s swimming straight to the camera so we are getting what we see.

Then we have Liesel from the side, and again, I had good feedback after I showed you guys this so I will definitely emphasize this but this is world-class breaststroke. With the segments you will see beautiful longitudinal appearance so here we go. Okay, I’m going to stop it right here. Look at that, that’s world-class breaststroke. And then I let her go one more round and then I’ll go to her training partner, another Australian girl, Sarah Katsoulis but look how straight she is, beautiful!

Now, Ron Taylor coaches both these ladies, Liesel and Sarah and when he saw Sarah when we filmed him in Gotham, we did this for him and then he yanked them right back into the pool and you’ll see why. At least he yanks Sarah in. Visually, you guys have seen so much video you can pick stuff up but when I showed them this with these segments, he freaked out. Look at this. See that? She’s not straightening her elbows enough and her head is down and when we go and finish the stroke you see how her head’s down, her elbows bent, and she’s rising to the catch a little bit with her hand? And her feet are a little bit low, she is not planaflexing enough and when we are talking about high speed these make a difference. So, I’m glad you approve but we’ll let it run here. But look at that? She definitely can improve her streamlining. I showed them both Liesel and Sarah at the same time so they really got a lot out of that.

Now we have this girl who is a graduate student of mine who is another American, dynamic apnea champion underwater, how you can go underwater, not for speed but she has got the streamlining down cold. You can see that this is beautiful streamlining. She has a neck weight so that she stays down, she doesn’t drift up but watch this streamlining here, a hundred and twenty meters underwater. She can get into the SEAL program overnight. But look at that, terrific! I thought you’ll have fun seeing this. Okay, then we’ll go on to Liesel’s kick going away from the wall, again you’re going to see a pretty good kick. So here are the trails coming up. She does something peculiar right at the beginning. You will see she does something funny with her toes, turns them inwards a little bit but that’s what a kick looks like and look how nice and symmetric that looks, so that’s nice.

We have one more thing which I think has a lot of potential and that is to be able to tell the timing of when the hands and the feet come up. So here’s her pull and as expected her legs are going to come up but if the legs come up late folks, there will be a distinct pause and you won’t see just this very brief time that the hands are out there. Can you see how brief this time is for Liesel? Because she’s bringing her feet up fairly fast. A lot of kids will bring their feet up later and you will see a lot of pausing, you’ll see a huge amount of time going by and you will see these lines much more elongated. So I think I’m excited about this little aspect because I didn’t realize that until we watched some of the other swimmers.

Fly. Here’s an example. This is Dao Lee from Singapore. We filmed the Singapore team and did the trails and segments for them last summer. She won a Gold medal in the Asian Games. I can’t remember her time but she’s pretty good. So we put a grid on her and showed her how symmetrical her stroke is and you can see this is a head-on view. Not bad, huh?

And then I have my piece de resistance, 1992, Pablo Morales. These are the tapes that Rowdy and John Malford [phonetic][ 0:38:11] and those guys all made. And here is 1992, the heyday of the keyhole pull. So, I’m going to play it and have you see for yourself whether Pablo was listening to his coach. He thought he was doing the keyhole pull. Now if that looks like a keyhole, there are some bridges I can sell you, okay? See the great swimmers swim well in spite of their coaches. He was doing what was very close to a Diamond pull because he realized he was able to get a lot more out of it. A keyhole pull and what I think we’re going to have fun when I have time is to film from underneath and get people to formally do a Keyhole pull and a Diamond pull and look at their hip velocity at a high speed and just see how much of a difference they…that I think would be a lot of fun.

And then, this last picture I’ll show you, one before the last picture, is putting the trails on the hip and the feet so you can see just what the amplitudes of the hips are and the kick. And you can see this girl has a pretty even kick and not too deep in comparison to this last guy whose kick is way too deep. We tracked the same thing, his hip and his feet and you can see a big difference and I think you can certainly do something more effective keeping the amplitude of his kick down. So his hips are not too bad but look at his kick, way too deep. Yeah, it looks pretty but I don’t think it’s going as fast.

Here’s the business of interference drag and I think Dave Salo, Rebecca Soni are on the right track because interference drag is the drag we feel when objects come too close to each other as they’re moving, and swimming generates transient internal interference drag. I didn’t talk about that earlier but transient internal drag simply talks about one arm, one leg going close to the body or the other half. The opposite of that is external drag which is when we come too close to another object like the wall or another swimmer. But we are mostly interested in the drag that appears when we’re doing things with our stroke so follow through and Backstroke, and Freestyle as I just talked about. Breast stroke, I’m really excited about starting to look at what the interference drag component could be.

So we’re going to use a camera here and as I mentioned earlier we just took delivery of this 2 weeks ago. First time we put the camera in we were so excited, I forgot to put the clips on and almost flooded a very expensive high speed camera. I flooded many cameras in my years of filming, the tell-tale horror is when you see bubbles, masses of bubbles coming out of the housing, boy, did we move this out fast! So that was the first real snafu. One week went by, second week, one of my graduate students decided he wants to insert this cable very tightly and he pulled it out and ripped the cable out so it took three weeks to get you what I am going to show you right now, but I think it’s worth it because we’re going to see some beautiful pictures taken from the bottom which is what we’re going to be working with on fly first then I’ll show you Breast stroke but this is what we’re going to do, we’re going to measure wing span and the changes of interference drag as they swim. So aesthetically, pretty neat. That’s what it looks like. That’s Fly but we’re not going to worry about the aesthetics we’re going to see if we can generate some information.

Here’s what Breaststroke looks like and look at how much the hip velocity has changed as they bring the arms in closer or wider. I think we’ll be picking something up. So this is Breast stroke. So things to look forward to, I’ve gone for 38 minutes so since I have a little less than 22 minutes I’m going to get on my soapbox and talk about this, I know I wrote a couple of things in the Journal of Swimming Research and American Swimming . I know Mike was talking about stabilizing a lot…stabilization, so I’m going to do a little bit more and give you a little bit of what I think is good information.

So the Kinetic chain, I’m not going to beat this to death. This is a nice colorful picture. Don’t ask me what the guy was thinking, who was in charge of annotating this. Scowl, shoulder, kidney. [laughter] Thigh, chin, and ankle but that kidney, boy, that does something for you! [laughter]. Remember the next time when you’re talking to your swimmer about the word Kinetic chain, don’t forget the kidney [laughter].

So, here’s the link system and I’m giving you a couple of really important words to think about and that is body movements are accomplished as a result of the summation of forces. I think that’s good information, along the links starting with ground reaction force. Now, and I said I’m going to get on my soapbox because ground reaction force is what we deal with on land. In order to get more bang for the buck, we have what we call a pattern sequence which is very critical. It may sound very trite but it has to be a sequence.

Nice picture to show that in order to generate force, you must have a stable base, we know this. Here’s a nice picture to show a ground reaction force. You have to harness; you spent all this money on expensive golf tennis shoes because we want to maximize our ground reaction force. So here’s a great study, I’ve been dying for years to stand up in front of an audience and present this because this is a study of a Tennis set [phonetic] [0:44:19] and hang with me. What I did was I looked at the forces required to hit a Tennis ball and I looked at this sequentially, and it came up with a calculation of about twenty-one hundred Newtons which is about 450 pounds worth of muscle force that imparted the velocity to the ball when it was hit, all right? So remember that number. Twenty-one hundred or 450 pounds, that’s how much force is needed to send the ball out to that velocity. The average mass of a male is 9 kilograms which is only capable of about 400 Newtons of force. Twenty-one (hundred) minus four hundred is 1700 Newtons, where did that come from? The 400 was just the muscle mass obviously. It came from the addition.

The addition and summation of forces all the way from ground up. So that sequential summation is critical. So on land, if you do it properly, you can add all these forces that travel up from ground reaction force up the Kinetic chain. And here’s a nice thing to think about. If you want to explain this, and you want to sound like you know what you’re talking about, to have distal mobility we need proximal stability, right? To have distal mobility we’ve got to have proximal stability. Remember, I didn’t say that. So what I did couple of years ago, I started looking at whether there is some simple way to explain this to people and what I came up with is a study where we measured the speed at which somebody was able to throw a Water Polo ball. We did a throwing study and I published this in my article in the journal Swimming Research.

We looked at people throwing, starting from the ground going all the way into deep water and I didn’t want people to think I was biased with the Water Polo players so I got a student of mine who was a Javelin thrower. So she knew how to throw but she didn’t know beans about doing things in the water but all we were interested in is the speed at which the ball left the hand. And you can see, the past ends [phonetic] [0:46:39] which is when you stand with one foot in front of the other, gave us the maximum velocity. You stand feet parallel, you’re not going to be able to throw as fast. You stand at hip depth, it dropped. Now standing at external depth gave us a little bit more and the reason for that is because the water provided a little bit more stability, she was not as unstable at external depth.

And then we went down to shoulder depth and then we put a vest on her and floated her in deep water, and you can see clearly, you cannot throw, no matter how much you try, when you don’t have the luxury of planting your feet firmly on the ground. It’s a very simplistic way to show a very important thing. The muscular system in this case has to provide the stability so the summary in swimming is that you have to be careful when you start talking about body roll. I will be happy to discuss this with you anytime, anywhere, but because we don’t have the luxury of ground reaction force, the trunk–the center of the body is the stable base and you don’t want to keep wiggling that around.

You have to be very careful about talking about body roll and I do not because body roll to me, and you can disagree, is a consequence of what you do with your extremities. If you watch any swimmer, they’re going to put their hand in and extend and you’re going to see a rotation of the hips. They don’t rotate their hips in advance. And if I want to be facetious, I can use as example of having you reach up to a shelf where you want to pick something up. I don’t know if you can see me or not but I wish you can, if I want to pick something up from a shelf I’m not going to go like this and then lift my arm. My hips are going to turn as I lift my arm up. As I said that’s a very trite example or a facetious way but it’s really what happens. I think the Body roll should be considered a consequence of and I’ll be happy to talk to you and we’ll have a fun discussion anytime.

Now let’s talk about the shoulder girdle and this was in the California Wellness letter which was very well put. They’re a beautiful piece of biological engineering but as with most beautifully-engineered pieces, much can go wrong. So, what am I heading for? I’m heading for these two things that I’ve been floating around. These are existing ideas. I call them diplomatically existing ideas. Pressing down on the T and opening up the scapula, elevating of the shoulder girdle. I think we have a lot of fun with this, I am.

First of all this business of pressing down with a T. I think the intent is a good one, all right? I have no quarrel with improving body position, lying prone in the water, lying as flat as possible, but when I read this statement, I shudder because one of the publications said in order to do this right, you must feel like somebody is pressing down on your shoulder blades. Now, you and I know that that’s not going to happen.

So, the other thing is this business of opening up the scapula. I’m starting to read stuff about people saying we need to open up the shoulder blades and all that stuff when they’re swimming. As I said, I’m not here to tell you what to sell but opening up your shoulder blades implies that you have to consciously do something to your scapula when you’re swimming and remember that’s part of the kinetic chain. Now you want to tamper with the kinetic chain? That’s fine, but this is what both these concepts ignore. What we call scapulohumeral rhythm folks. The shoulder works because of the movement of the scapula. The problem is it ignores this. The shoulder girdle and the shoulder joint move together so here are the typical biomechanical textbook pictures of how complex the shoulder girdle operates. Can you see all these muscles working in different directions? We call this coupling, forced coupling.

Let me go back here real quick. We call this forced coupling because we have muscles working in different directions all giving us one particular movement, so it’s not as simple as it sounds. I found these pictures for the different positions of the shoulder girdle. This is protracted, meaning the shoulder girdles are away from the spine. This is the midposition, and this is the retracted scapula. I asked this young guy to lie on a Biokinetic bench and try to press down on the T and I went above him and took a picture. You can see his scapula shoved into his spine. And if you think about it, when you throw, the last thing you’re going to do is to shove your scapula embedded into your spine and then cock you up. That’s not the way it works. So as I said, attempting to isolate the scapula during arm movement is not conducive to efficient stroke mechanics, all right? Again, I’m in a facetious mood so I say I don’t think you’re going to go down to practice one morning and say today we’re going to work on our elevated scapula and our rhomboids, okay? [laughter].

Now, the business of torque, those of you who are sitting here, again hang with me, but torque is what we use when we are lifting anything and we have a foursome to contend with. What we have really to be concerned about is maximizing or minimizing external torque and here’s the picture I had of the spine, dynamics of the spine, we want to keep those boxes as close as possible because the internal torque we can’t fuss with. The distance between the spinal muscles and the center of the spine is tiny so you can imagine the magnitude of the forces generated by the spine in order to counteract this external torque and that’s why people get hurt.
The other good example is with the head. If you ever had any doubts about placing your monitor at a not neutral position, look at this, this will scare the daylights out of you. When you tilt your chin down, you go from 25 Newtons of force in your muscle to a hundred Newtons. A hundred newtons is about 25 pounds. You try putting a 25-pund weight on your neck and see what it feels like. So what we’re interested in is when swimming, there’s torque. That’s what we don’t have control over and that’s what we want to minimize, so in reality, lifting our arms up with the elbow straight and stuff, locking our elbows is tough on the arm and that’s what we are saying here.

And then we have the shameless plugs as I said I’ve been asked by John to take over the Journal of Swimming Research and here’s what you’re going to see in about a month. I hope you get on, we have a wonderful group of editors and then we have a Coaches’ Review Board. They are going to be responsible for screening the articles because unless our regular manuscript is not accompanied by a coaches’ version, it makes it a little bit easier to understand. A manuscript doesn’t go in.

And then I want to make another shameless plug for my website, if you want to call swimming by mechanics which is going to give you more information about the video enhancements and all that stuff. Now, since we do have time, I’m going to show you something and let you go and have you think about what you’re seeing. And I was going to put this in and I’m glad I have the time but I’m going to show you something that you’ve never seen before.

This little boy has what is called Thrombocytopenia-Absent Radius Syndrome, long word for bone without arms. If you notice, he also has his feet, the mirror image of ours. So I’m going to show you a video clip of this. This guy is a modern genius. Watch him. Just sit back and watch. Nobody taught him to swim folks! Okay, wow is right. Isn’t that amazing? This is what he has learned to do. Now the big thing is, he is incapable of any linear type of movement. His feet are like propellers and I’m going to show you after the head-on view what he does from the side and it’s incredible how he generates this rotary movement. Okay, watch him now from the side. The human propeller. Isn’t that amazing? It’s very moving. I mean this kid on land is virtually immobile. Right there. So I thought you’d enjoy that and I’m glad I had the time to do it.

Dr. Prins: One of the surfing movies had this segment which really caught my attention and I think it’ll…why don’t we do both? That’s a little bit more sensitive, so let’s do this here; I’m just going to play this. So let’s see if it plays. This is Kenneth Slater talking and I’m just going to play it again and see what you think. It’s going to make you think.

Kenneth Slater: It’s got to be one of the most amazing feelings out there, as far as any sport because to be able to control something that’s not controllable [overlapping][ 0:57:11] it’s like riding a wild force, it has its own attitude, it has its own power. At first it was sort of exercise purposes for myself, I’m talking about seeing this, imagining it, being in awe of it, you know, millions of flat surfaces that you’re turning in, you know that’s just more of a feeling that after all, what I’m seeing is not…I’m not seeing something digital, I’m imagining this, wherever I’m turning, any point that I’m pushing off of is a flat surface and my board is flat and the bottom of my board is pushing against a flat surface. My body needs to relate to that part of the wave, on that angle, whichever angle it is. In this angle, flat coming off of the bottom, on a flat surface up on the face of the wave, more than a hook to the wave and my board is pushing, constantly pushing my energy against that and then it releases forward.

Dr. Prins: So, before you laugh at the cat at my grand finale you can see the subtlety of what Kenny Slater’s saying. And I hope you share my feeling about that because that’s what it’s all about. It’s a little bit like a nebulous feel for the water. This guy is doing what we’re trying to do in swimming, find a surface that he can push against, he is the 10-time world champion, I think he’s going to be the 11th this year but… he did by the way, he hasn’t finished yet. You see? The reason I show this to you is because it makes us think. So…
END.

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