Swimming Biomechanics | Dr Pedro Morouço

Hello and welcome to lecture six of the Sports Biomechanics lecture series supported by the International Society of Biomechanics in Sports and sponsored by Vicon. In the first of our three lectures today I'm joined by Pedro Marusso from the Polytechnic Institute of Liria in Portugal. Pedro was actually winner of the ISBS New Investigator Award in 2014 and he's got a lot of interesting research involving the biomechanics of swimming. So today he's going to give us a brief overview of some of the literature in the area of swimming biomechanics. So thank you very much and over to you Pedro. Well thank you very much Stuart. First of all I really would like to thank the opportunity for making this presentation. Really thank you for ISBS but also and most of all thank you for Stuart for coming up with this hard work getting many people talking about their passion and what they love to make research about. So indeed when I was invited to talk about swimming biomechanics in this type of situation that we are living in I got a little bit stressed up about what to talk about without taking one day totally or something like that but to make a short presentation about half an hour on swimming biomechanics. So before that if you saw some of the previous lectures and if you didn't I really invite you to do so. I would like to start by telling a little bit about myself because I really think that is very useful for the ones who don't know me. But there's one big thing I would like to tell you that I was born fat. So it's really I was born really really fat and probably because of that my parents put me to play almost all sports that you may know. Apart from sports they also put me on the ballet. So as you can see on that picture that fatty guy over there it's me. And so for the beginning that I remember human movement was always on my mind. So I was one of those guys who didn't have any type of doubt about what to do in the future and it would be something related to sports. So indeed I come from a small city here in the middle of the country. You can see over here. And so when I had to study to get my degree I went up north to a faculty of sports of the University of Porto that many of you already know that is a very big institution regarding sports sciences and where biomechanics has a role a fundamental role for the student. And from there I took a very well let's say hard decision on 2001 on the exact same day of the World Trade Center came down. I had to choose an option and I decided to take the option of swimming. And that was something that was by the time something that really was challenging because what we used to say is that when you put water everything becomes much more difficult. And so as you can see we were a small group of people over here. If you see the picture of the ones who selected for instance soccer you will see that they are much much more. So we had the challenge to really come up as a group interested in swimming mostly interested in swimming biomechanics and physiology. And so it came up to be one of the best decisions I took in my life. These gentlemen over here some of you may know it's Professor João Paulo Vilas Boas. If you go to the web of science and you search for the topic swimming you will see that he's the top leader author and most of all he was he's probably responsible for being the father of so many young researchers that in Portugal and abroad are making very big very important research on the field of swimming. So it was for me a huge pleasure to be student of him and try to learn with the best. There are some examples like Professor Ricardo Fernandes or Professor Tiago Barbosa that many people know are top researcher on our field. But apart from that and I was supposed to be talking also to some of students that are nowadays taking for instance their first degree or even their master degree. I have to tell you that swimming became my passion. So indeed when you are studying you should try to find and reach what you get in love with. It will become much easier and of course it will be much more interesting for you to keep working on that on your free time. So I really got enthusiastic with the idea of the water's induced biomechanic issues and I tried to do everything I could to get involved with the ones who could benefit the most with the swimming biomechanics that is the swimmers of course the coaches and even when you find obstacles on your path don't quit. So there was no funding for me to go to the World Swimming Championship in Manchester but I was able to get a backpack and sleep in a hostel and by myself become a volunteer of the organization and get to know the best swimming coaches of the world. So just a final remark about who I am who knows me tell me that I'm a workaholic but I do expect that before this situation that we are living a little bit like this and after I suppose the same. So regarding biomechanics the main question that I really would like to talk about is how can it be useful for swimming performance in this trying to increase the swimming performance of our athletes. As you can see down here there's my email so please feel free to use my email or my twitter account to get in touch I will be more than happy to keep the contact further this presentation. And about biomechanics and you can see here I'm sorry now starts you can see you can see here then the video that this is front curl on both videos. So it's the same swimming technique the same swimming stroke but the truth is that they are totally different from the left to the right side. So the main thing that I got interested in the last few years is that when you are talking about the same stroke you might be talking about different biomechanical constraints that will surely have an impact on swimming performance and if so I made this draw over here and if we were live getting feedback response in real time I would like to ask you how do you think which will go with the world record for the 50 meters freestyle to the 1500 meters freestyle. So if you put here the 100, 200, 300, 400, etc. if it will go like the orange curve, the blue curve, or the green curve. And one interesting thing that you might do this homework is that you will come up with an almost perfect correlation between the time and the distance. And indeed when we start thinking about this we come up with a very interesting idea is that swimming is a very easy sport regarding the rules and what you have to do. You go to the starting walk you already know the distance that you have to travel. Most of the elite swimmers already know how many strokes they will have to do to finish the event and so you have to make it the fastest you can and that's it. The main issue is indeed how can you make it faster and how can you make so that the energy that you are using is really really used for the purpose that you want. So how not to spend energy that is not efficient and as I said at the beginning swimming biomechanics need to become your passion to really go over this and try to understand clearly how can we come up with tools that might improve the performance of our swimmers. So this is a small example of some of the things that I get really enthusiastic about and I think that studying is one of the most important things that you can do for the rest of your life because when you study you have you must have your open mind and with that open mind you'll be able to see what others are coming in conclusion with and how can you use that for your daily work. But also from studying comes a different thing that really should be questioned about that is your experience and the experience that you go through will tell you a lot of things about how to work. I have a small experience that I really really came up to me when I had some time to think over it that was with the olympic games in Beijing 2008 when I was making some biomechanical evaluation not from the swimmers but from the national olympic thrower. And by the time I was really really only looking up to the biomechanics and the bioenergetics that was only the only it was the only thing that was I was thinking about because I really thought that would be the only important thing and I was able to understand that even if you make the most rigorous work on this side there will always be a mental side that really comes up with the final result. So we should not try to elevate something and forget all the other aspects because there is a multidisciplinary issue regarding some performance on sports and most importantly on swimming performance. So with that in mind well probably most of you know about this issue here on the Beijing olympics and the finish of this event and I usually say that when you look about genetics they give us the tools like everyone tells about how the mechanical issue for Michael Phelps could be improved regarding his anatomy but indeed I do think that biomechanics teach us how to use them. So if I have some type of genetic profile and that will give me some type of stature and arm length probably biomechanics has the skills to teach me how to use them the most correctly as possible. So with that in mind I would like to tell you that regarding the forces that the swimmer produces inside the water that's something that we've been trying to understand for years and most of the evidence really comes up for what the swimmer does and then we try to understand why does he does it and so different type of evaluations come up some of them on dry land some using hand pressure systems some using some mechanical models or some force reducers on the mat system and the one that I was working most I'm working most throughout the last years is indeed using a load cell connected to the swimmer so that the swimmer can make his stroke at the same spot using both arms and legs while you are recording the forces that he is producing. That idea well Maggio in 1970 came up with this proposal if ever here you can see it was in paper was really really hard for me to understand how can we without the technology that we have nowadays make some type of evaluation on paper and trying to understand for instance average for instance difference between the right side and the left side etc but he came up with this approach regarding well he used the idea of Karpovich in 1939 and then he improved it and he came up with this situation and indeed throughout the years we have so many advances on technology and for sport sciences that was also very very interesting because it made this available to get much more data and much more information but the main thing I really would like to come up with is that throughout these years and as I said at the beginning my main issue has always been trying to understand how can these approaches how can this swimming biomechanics how can this evaluation be useful for the swimmers and probably it's my idea and my way of working but I'm not so much concerned about publications about making the papers on the best impact journals I really think that it's important to spread that and to disseminate the knowledge but most important in the first situation is indeed trying to be useful for the athletes and in this case for the streamers so I do know that getting in evaluation system and trying to see how am I able to draw the profile of the swimmer that will identify me that will identify me at that precise moment which are his strengths and those weaknesses but when you talk to coaches and these are just some coaches from Portugal taking it for a step further on their course on their skills and the main issues that they are always questioning is that indeed if I do know what parameters should be evaluated how can they be evaluated when should they be evaluated and even more important how often should they be evaluated because at least from the research that we've been witnessing in the last years we do know that when it comes to swimming practice there is a big doubt about how to increase volume and how to increase intensity and we cannot go infinitely to increasing volume so we need to work on the appropriate intensity so that you can get the best outcome of your training and indeed this is something that they know that I focus a lot is that how can the results be used in the real situation and many times we are well surrounded by the pressure of publishing or perishing and so we do a lot of intricate studies but without the tools that really are useful for the streamers that sometimes are very very easy to come up with and so this is just a small example of something that well it comes up with the passion that I talked about and in 2003 in my city there was no chance of having a super aquatic camera and so I went to a shop and I bought this surveillance camera over here a very cheap surveillance camera and with some few adaptations I was able to put it recording underwater and at the same time using an above water camera I was able to get a dual system and I can tell you that for getting this camera over here that is the conventional camera I'm talking about 100 euros over here and I'll tell well 15 or 20 euros this type of trolley so it's very easy to get this type of approach well in 2003 now we have gopros now we have other tool systems but the most important thing is really don't quit when you don't have the best equipment that you should like or you would like to have to make your your research and so getting a little bit with imagination I was even able to get the four cameras working at the same time and so that I could record on the frontal plane and or the digital plane at the same time and indeed try to be useful making some kind of qualitative analysis so this for me was very important just to say you one thing that when you get some obstacles that you probably will don't give up never so try to talk to everyone you know try to come up with an idea of how can we overcome this difficulty and now can we really come up with the ones that you were things that you want to study I'm sorry let me just get this volume down because it was very very loud for me but just to give you an idea like this is the swimmer swimming what I will call free swimming so there is no nothing interfering with his swimming technique he's swimming comfortably throughout the pool and I selected a backstroke on purpose because you can use well any type of stroke that you want you can get the instantaneous velocity of the swimmer but what you can see is that he has attached to him a speedometer so you get instantaneous velocity of the movement but many times the kicking will interfere with the results that you are trying to measure and you are restricted to one swimming pool as you can imagine if you are working on a 25 meter swimming pool that's the distance that you can cover so feathered swimming for the ones who are not so aware of it it's using a swimmer so you put the swimmer connected to a load cell over here there is a small angle so that you can avoid that kicking process on the wire and so he swims on the same spot you can change the intensity as you notice he started slower and then we got the whistle and he started marking it um with more intensity you can use it for the fourth stroke the four strokes you can use it using equipment or not and try to see the differences so there is a real world uh that you can use for this show I just would like to get something that when we read the papers we really don't get with that idea there is many people uh think that when I talk about the useful that that can be they see some kinematical changes well of course they do uh and if you go to the gym you will see that a bench press is much more different than this to real stroke but they keep doing bench press so the idea is not use these as a tool for training by itself for many time or well high volume the idea is using this to make evaluations and indeed try to understand how the forces produces in water are getting uh what's the behavior of those forces so with that in mind we come up with some ideas on how could we validate this approach and try to understand if it was very similar or not with free swimming and it is worldwide people are using tethered swimming and comparing it with free swimming and the differences well there are some kinematical differences but so short that indeed it can be used for uh swimming evaluation and for instance both in stroke rate a biomechanical aspect or in the lactate production more on the physiological side you see that there are indeed very small differences between the two approaches and you come up with something like this so as long as he's swimming you are getting this instantaneous force production and something that I really would like to make give up the challenge the challenge to you that are hearing me is that this is something that we come up after 30 seconds of stroke and you can see there is an average and there is some variation so my challenge is indeed we should be looking further to something that came up in 2007 on sports biomechanics that is this movement variability and how can this be really really important for the athlete's performance and on this case for the swimming performance so from that side you can see that we have the instantaneous force you can separate the right side to the left side I called it dominant and the non-dominant and you can see some asymmetry regarding the force production you can even see some type of behavior that all swimmers presented apart from their level so I'm talking about elite streamers but I'm also talking about lower level swimmers they are asymmetric and they are symmetric not only on the force production but also as already stated by research french researchers on upper limb coordination or even on the end path so if the streamers are symmetric let's call it like that how can that be useful for me on the biomechanical side indeed how can we know if those asymmetries may alter the optimal function or they are within the thresholds of normal variation I really suggest well I you might see the link over there but it's easy to find the papers from Ross Sanders on 2011 12 and 13 on the journal swimming research when he really come up with some interesting ideas on asymmetry and don't forget what I started to say that is swimming the 50 meter freestyle it's totally different from swimming the 1500 meter freestyle both using front crawl but with several differences regarding the issue apart from that you may also use tethrid swimming to put the swimmer using both the upper limbs and the lower limbs or you can constrain his movement using only the upper limbs and only the lower limb and if you can do so you come up with something also very very interesting that is as expected when he uses the whole body he makes much more force he's able to produce higher levels of force of course and when he uses only upper limbs then he can produce higher forces than using only the leg action but the main interesting thing that really come up with my mind was what's happening with these 15% when you make some calculations of a swimmer that okay so let's say that he gets 100% of the force production when using the all body but only using upper limbs he's able to reach the 85.7% well with standard deviation around 8 and then when using only the leg kicking he's able to reach 35% so this is the results from one swimmer but on average that's something that we've been having and if you make this plus this you will get over 100% so what can that tell me what can this value over here tell me when i've made this deficit of i will that be useful for me once again this is also a symmetry this is also regarding the differences that you can achieve from the upper limbs to the lower limbs and how can we know if they are not are or not in the normal variation i have this idea over here from casking in the late 90s when he was saying stating that indeed when you are talking about propulsive forces and swimming velocity they should be balanced and if they are not balanced if you fit over here probably you will need to have some improvement on your propulsive forces and if you are somewhere over here you need to have an improvement on your swimming technique so this is the well this is a theoretical statement but a very interesting statement regarding the relationship between the forces and the speed velocity and we do know that swimmers aim to be well applying most of the time forces in the water and with that they will come up with an well it will certainly occur a variation of velocity in each stroke cycle and this is a interesting issue that there are a huge amount of manuscripts working on this intercyclic velocity variation and how it can be considered an efficiency parameter once again always having in mind the performance optimization so for me the main result comes as i previously said looking at the subject looking at the swimmer at that precise moment so i come up with this data these are different swimmers these spots are different swimmers with their swimming velocity and the forces exerted and that tells me something that i really should look at each one of these is a different swimmer i should know who's who's who's who so who's this red one who's this blue one why because i really should understand that they are in a stage where they should increase their strength i need to focus on their coordination only with that an appropriate coordination which will come a speed increase and with that speed increase we should also be aware of that coordination so if you take a look at this situation right here and if you study the same subject and you evaluate them again three months left again later see what happened they are over here and now they change they change some for the right some for the left some for up some for down uh but the well if you are only interested in the average they will keep more or less the same but indeed watching this will tell us if the strength increase that we are achieving is or it's not being useful to increase speed the speed the speed the swimming speed and if that is not happening coordination work needs to be done some of the later approaches that we've been working with is that indeed trying to understand if the intercyclic variation of velocity can also be used as the intrinsic variation of force and i didn't put here and i would like to ask you to try to guess which one is force and which one is velocity you see they are very similar right when i come up with the values of course then you can notice that upper is the velocity and lower is the force but we are talking about the technique for evaluation that comes up with very similar resources to free swimming and if so probably using also the intercyclic variation of force that is something that i'm researching with spanish colleagues right now it's using it on the swimming pool loom as a way to make some quantitative analysis of the swimming technique but as i said most of the times i'm really really interested how can we be useful and how can we translate this to something for coaches that are not available to have a load cell and measure the strength forces that the produce the swimmer produces underwater so just to finish and to tell you something regarding the future and what i'm looking up further further is that trying to get interesting results on swimming biomechanics that are user-friendly and that is something that well every biomechanics is always thinking about how can we be useful for the coaches so this small device that you can see over here is attached to the back of a swimmer and there's something that i really think is interesting for everyone to understand that is with this device the swimmer can go and make all the practice and i'm talking about two hours in the water or more than that in the water and then the coach comes home it takes the data on his computer and one of the important things that the system does immediately is that the coach doesn't have to tell the system which stroke he was swimming on training so immediately we can recognize if it was front roll backstroke butterfly or breaststroke i will show you a short video it will run very fast because i really cannot show this yet but uh just give you an idea about the future as i said you just need to select which is the length of the pool and upload and it will run very fast but try to understand that we immediately can get the results on each stroke and get very data on one training and have reference of best trainings for all the swimmers that are using the equipment and this is something that i think that we will be looking in the future because we need to understand that the tools need to be useful for training and so the coaches cannot be waiting one week or two weeks for the result with this system they will be able to immediately get results on body rotation trunk inclination stroke rate stroke length velocity throughout two three hours of training finally telling you that the statement was this statement is very interesting but nowhere in sport is performance so dependent on the interaction of the athlete with the surrounding medium than in competitive swimming so if you are studying and you really need to or really want to come up with some challenging ideas putting water on this situation will certainly be a very interesting challenge for you finally thank you once again for isps for having me never forget to learn with the best because keeping humble and keeping your open mind will certainly have a very good result for yourself so as i call myself be a pain in the ass and try to well reach the best you can and try to get the most information you can from them just don't go to conferences be quiet if we have questions please ask them get in touch with the speakers etc etc thank you very much all the swimmers that i had the chance of meeting throughout my life because indeed this would not be possible without their cooperation thank you okay brilliant thanks pedro that was really really interesting i know i said at the start when we were chatting before we went on air that swimming biomechanics is an area i find really interesting mainly because i'm terrible at swimming um but also just because of all the problems in data collection that pedro touched on so i know for most sports biomechanists could rock up at the venue set up their equipment and start collecting data but if a swimming coach said to me can you come along and collect some data in our training next week i'd have to go away and do a lot of reading and research into how can i actually collect that data because a lot of the techniques we normally use wouldn't work for obvious reasons with the water involved so that was really interesting um before we quickly go on to a few questions just a shout out that all of the other lectures scheduled are on the screen now so if you haven't already go back and look at the five lectures from previous weeks this is the first of three today we've also got a couple of talks relating to football or soccer and then there's another couple coming up next week as um but my first question for pedro i'm really interested in movement variability and functional variability which you touched upon a little bit so i was wondering if you could go into any more detail on either the asymmetry or just variability between strokes on for example are do elite swimmers have more or less variability than lower level swimmers or are certain aspects of the stroke more variable than other aspects i don't know if that's something you're able to touch on but it's something i'm quite interested in well well yeah to to be honest that's something that i'm really really interested also um and uh well when i was making for instance my phd i was not even looking at that so but i have all the data so i'm looking at that uh in the last few years and indeed it is quite interesting that you find similar variability both for the elite swimmers and for the lower level swimmers and that really came up with me with with my mind regarding for instance the idea that i had about the asymmetry as i well theoretically i was thinking about being symmetric would be better for the swimmers but the truth is that for very high level swimmers swimming the 50 meter front crawl they want to be the most propulsive as possible on the strokes most of them really use one end to make much more impulse than the other so they are swimming asymmetrically in purpose and indeed we were able to many to measure the mechanical impulse and understand that they can reach higher impulse than a symmetric guy so there are so very big differences in the same swimming stroke because if you then go to butterfly or for breaststroke well it comes up to be some other different challenges because as you can imagine in the simultaneous technique you will have for sure long periods when you are not able to make propulsive action so i really think that in the future much more research needs to be done regarding this variability because to be honest on my phd we use the average and the standard deviation and the coefficient of variation to understand how was the variability and we are far from understanding how can this variability be one of the most important issues for increasing the swim performance okay yeah really interesting thank you um my other question that i was quite interested in was this idea that the arms of the upper body in isolation um it was around 85 percent of the force produced or applied by the whole body and then the lower body in isolation i think about 35 but the idea that both of those numbers together is considerably more than 100 and kind of i wondered if you could go into a bit more detail on why that might be yeah that that's that's something that uh i i do think that they have the link of some of the manuscripts that i that i made the reference and so there is one uh one paper regarding this relative contribution of the upper limbs and the lower limbs because what i noticed is that um when the first studies were done um they were really stating that well it's about 85 to 90 percent dependent on the upper limb so in your mind you start thinking that the leg kicking is only important by 10 but we if you start reading some manuscripts and you start making some testing you will see that the importance of liking is probably much higher than 10 because indeed we are not talking about just taking the less of the 100 minus the 90 um what we came up with was values for all swimmers above the 100 and what we were able to understand is that the last coordinator swimmers coordinated swimmers were the ones who were able to achieve higher values of upper limbs and higher values of the lower limbs but then were not available to reach such higher levels when using the all body so that value over there that i presented we called it force deficit was higher for that and this is interesting not only when you are using separate swimming but to put the swimmer making a trial making a free swimming on your swimming pool using the all body or using only upper limbs or using only lower limb you will certainly see that you have streamers who are not able to translate when using the whole body and for me it is mostly due to the coordination of the swimmer and his ability to make the perfect synchronization between the right and the left side and with that with the upper limbs and the lower limb okay um yeah really interesting again so just as a follow-on to that because i was wondering whether it was in any way due to certain musculature being involved in both the upper limb and lower limb aspects but based on what you said about coordination do you think that the actual figure as in how far over 100 percent it is would maybe vary for different levels of swimmer and that might be some kind of indication of coordination within the stroke yes yes that that's my main idea so as you as you can imagine like well all all the high level swimmers they make strength training on the gym for instance and if you notice that your first first thing if you notice that your swimmer is increasing the strength on the gym you should be expecting that he's being able to increase the force production in the water so his speed will increase so that's the first question that we need to understand is really having a transfer between one between what's being done in the gym and then using it in the water and if it is is it making a equative improvement regarding the upper limbs and the lower links and the coordination between them and indeed what i came up with is that that the idea of having each swimmer understanding what the behavior of himself is that if you have a swimmer that comes down and right on that evaluation it will probably a swimmer that needs to improve his swimming technique and the swimming coordination so it's not the most useful thing keep increasing the strength on the gym or in different tasks that you do in the water if without working the coordination of that thing okay well while you're answering that we've now got a couple of questions from viewers on youtube and so i'll try and kind we'll try and get through those quite quickly um but the first one from the fit owl who says since swimming is a whole body movement is any kind of kinetic testing of any use or application to that i'm sorry stewart i think that uh the question was uh we are using the whole body uh can we do some type of measurement right yes so with isokinetic um dynamometry so strength testing and say the knee extensors or knee flexors um for example would that transfer to swimming do you think or is it okay yes um let me just tell you that um many many years ago there is a book uh by looking at medicine many years ago and it is quite interesting to understand the tools that they propose to increase the speed by the time they they really got some interesting ideas regarding the velocity of the movement and so isokinetic systems are being used mostly to understand something that all swimmers are worried about that is lesion so injuries uh let's say injuries um are one of the issues that we really need to be aware of and using isokinetic systems is one of the ways of measuring the the ratio um between for instance the shoulder um the shoulder anterior and posterior length of the of the muscles and power of the muscles so indeed not so much on the swimming performance because when you are talking about the stroke cycle you do understand that the velocity of the end is increasing throughout all the movement and that is probably one of the things that most motivated me to use the factor of swimming because you are indeed not changing the pattern of the end and the velocity of that end while if you are using uh is that isokinetic system for instance in dry land we're using the swimming bench probably you are changing a lot of the end path but also the swing velocity of the end and so as i said um if you have the swimming bench and if you can use it to make the isokinetic evaluation uh try to use it try to see if there is some imbalance between right and left arm but try to understand further on the approach in the water to see if indeed uh those well witnesses that you detect are or not transferred to the water thank you and the second question is from dagal bronski apologies if i've pronounced that incorrectly um but dagal says thank you for the talk i'm doing a phd about the fluid mechanics of underwater fly kick and i was wondering if you've ever had to estimate the efficiency of this technique and how would you do it or i guess if you haven't how would you estimate efficiency of thank you very much for the for the for the question because the um indeed that's something that i really never uh got into it uh we had as i said i made most of my research on the first degree and on the master's degree in the port university they have their uh biomechanics lab and they have a very strong research group on clean biomechanics but most of the issues that we were studying at that time was indeed trying to understand how the kinematic and the kinetic analysis could be performed or could be enhanced in the water and so studying the fluid mechanics is something that they come up with very brilliant ideas mostly regarding the approach that they had with the engineering uh faculty that is just on the other side of the street and i would be more than interested in giving some some manuscripts and some papers that i have um i just well we edited a book on a sports science performance that i would be more than able to share with him if he just sends me an email where there are some ideas on how you can measure that efficiency there are some japanese researchers that making a very interesting work they presented it in the biomechanics and medicine conference um and so i really wish you the best on that phd because it is indeed a very very interesting um idea and if i can give you my my my ideas that don't quit with the difficulties that you will have because when i was in manchester in the the world swimming championship i saw um the most interesting um the most interesting underwater click kicking and indeed that's something that in the future it will make an even bigger difference between the gold and the silver medal because the underwater phase is something that we really need to look and i'm always telling the coaches over here that they spend well i will say 90 of their time on the swimming and the 10 of starting and turns and that needs to to be thought about and probably give much more interest much more detail on the start and turns technique thank you it's um it's really great to offer your advice and insight and help current students out as well if anybody else does have any questions for pedro then either use the comments on youtube and we'll keep an eye on those but if you get in touch um over twitter we'll try and get any answers to you um yeah all that really remains for me is just a huge thank you pedro that was really really interesting and something i know both myself and hopefully a lot of other people will have benefited from and have been exposed to a whole new area of biomechanics and research so thank you very much for that and the people watching please don't forget um the other lectures on the screen as well thank you very much