 Okay, hello everyone. I am Stuart McCurlay-Maylor from the University of Suffolk and welcome to the Sports Biomechanics lecture series. First off, I need to thank ISPS, the International Society of Biomechanics in Sports, for their support in both organizing and promoting this. And of course, I must say, all views are those of individual speakers and not necessarily ISPS themselves. My second huge thank you has to go to Vicon for their financial support in allowing this to go ahead and essentially allowing us to reach as many people as possible. So with that in mind, we've tried to pitch it so that it's suitable for the majority of undergrad sports science students. So there may be the odd recap thrown in and if there's anything you want to explore in more detail, then just ask a question or things can be explored in more detail as part of existing programs. Okay, so that leaves just the biggest thank you of the day, which is for Alastair for agreeing to go first on this. I'd like to introduce Dr Alastair Dempsey from Murdoch University in Australia. He is a senior lecturer in biomechanics and sports science. His research focuses on understanding the neuromuscular biomechanics behind sports injury and musculoskeletal diseases, and he's kindly offered to do the first lecture on the biomechanics of preventing sports injuries. So thank you, Alastair. Okay. Thanks, Stuart. Get on to the right screen. There's a nice little slide there that says basically what we're doing again. So we'll move on and really talk about why do we care about injuries? If I was to ask everyone sort of live how many people have been injured, how many people thought it sort of sucked, it's probably most of the people in the room, particularly for me when I'm talking to a very sports science group of students. But also sports injuries are a big issue. So in Australia, so this is just Australian data. In 2016-2017, there were almost 60,000 hospitalisations due to sports participation. This is not going out and rolling your ankle, treating yourself with the right. So this is going to hospital, ending up in ED and having further treatment from there. So it's not a cheap sort of injury to manage. Hospitalisations and today's environment, we don't really want to be ending up in hospital. So when we look at that, most of these come from the football codes, netball and basketball. So our team sports and the football codes, Australian football, which is our sort of native code here. The two rugby, so rugby league and rugby union and association football or soccer. Netball for those who aren't from a Commonwealth country. It's definitely going and having a look at a netball game because if you were to design a game where people were to get injured, it would be netball. What's really good for us from an injury prevention point of view is a large proportion of these injuries are due to non-contact mechanisms, which means that we can actually intervene at the level of the athlete or without having to change too much and actually come up with some sort of positive outcome, positive mechanism. We don't have to change again. We don't have to do anything about it. We can intervene and change the athlete and change it, how they interact with their environment. So when it comes to injury, it's really all about the load and the load that we experience. And when we get injury, we have the load which is too big. We have a load which is in the wrong direction. We have inadequate support or we have inadequate loading frequency. We're either loading too much. So we get our overuse injuries or we're loading too low and quickly transition to a high-frequency load. And that's a lot of where our workload management comes in. So really the interaction of these four factors are what leads us to getting injury. In the end, a tissue is going to get damaged when the load that you apply is too big for the tissue's ability to cope. So to get your elastic band, you stretch it, you stretch it, you stretch it. It's all good and then it breaks. The same with any of our tissue body structures as we go through. So if we look at injury prevention, there's lots of models out there around injury prevention. The one that I really like is the one proposed by Carolyn Finch in 2006, which takes injury prevention right through from our initial phases through to actually getting people to do the injury prevention. So if we look at that, the first step is obviously to look at what injuries are actually out there. So who's getting injured? How many people are getting injured? And that becomes a sort of a big thing. If there's one person who gets injured and no one else in the sport ever has through that mechanism, trying to prevent it is probably fraught with we're doing a lot for not much bang. If we have an injury which doesn't have huge detrimental outcomes, for instance, say a hamstring or most hamstrings, but that happens a lot, we want to intervene then, or something like an ACL, which is what we're going to talk about through most of this lecture. So the anti-recreation ligament happens relatively regularly, but when it does happen, it usually leads to about 12 months out of sport, which, you know, for the Joe Blow athlete or even a professional athlete is not something we want. So once we know what injuries are actually carrying, we want to intervene. And to intervene, we first need to establish how the injuries are actually carrying. So look at where the injuries are carrying and also look at the mechanism of injury. So once then we get a good handle of that, we can go through and work out what our intervention looks like through our programming, if we're from an exercise science background. Then we should be testing it out in an ideal condition. Everything's perfect. We're a nice controlled experimental environment. And once we know they're in at work, we can go out and we can say, how do I get this from my lab to everyone in the country doing it? And then finally, we need to go back and evaluate. So where does biomechanics come in? So it really sits through steps two, three and four. We're not epidemiologists. We're not going to go out and do the surveillance. Most of us are not going to be doing the implementation phase, but we're really about understanding how we're getting injured, developing prevention measures from that, and then going through and doing the evaluation. So if we work to all of these, and this is the work that came out of my PhD, looking at how each of these steps work. So the first step is really to look at how we're getting injured. So look away now if you don't like gory videos, but this is an example of a contact ACL injury. So if you watch the guy coming across here, just turn a pointer on. If you watch this knee here, he gets hit. He gets into knee abduction, rotation, and ACL is gone. And from an intervention point of view, there's not much we can do about that. He's being crushed into these knees, completely legal environment within that sport. So there's not much we can do without really changing the way that sport is played. The next sort of injury is an indirect contact. So we can see that he's had his loading environment changed by this player here. And then we've had this injury here on his left knee. And again, there's only so much we can do to manage and intervene in these sports. And finally, we now move to our classic ACL. So you watch this player here from Essendon. If you watch this left knee, sorry, Essendon. I forgot I'm not speaking to just Australian. Essendon's a team in black and red. We can see that as the player comes in, he throws his leg out and his knee collapses in. Now, one thing to note when he actually gets injured is that you can see that he's placed his foot a long way from the midline of his body. And he's leaning his torso back over this support leg. And we'll see that same position if we look at other ACL injuries. So this is where England lost their 2006 FIFA World Cup bid when Michael Owen snapped his ACL. I do apologize for anyone in Europe or anyone in England who's watching this. But again, as we see, he goes to suddenly change direction, throws his leg out a long way, and we can see it collapsing down and in. So again, at full contact, his foot's a long way away from the midline of his body. And here's a more recent one from AFL, the women's AFL. If you watch this left knee here, we can see that as he goes to change direction, the knee, again, a long way away from the body. Torso is coming back over there. And we see it collapse back in towards the middle of the body. So before we go into the next step, just a quick recap, depending on where you are in your particular course. As to what a moment or the moment of force or torque, we use these terms interchangeably. I think much of the exercise science or sports area talks about it being the moment, which is really the turning effect of a force, not a moment. I do apologize with my typo there of my words. And the important thing to remember is how do we calculate our moment, or the two components of our moment, is the force and our moment arm. And the moment arm being that perpendicular distance from an axis of rotation to a line of action of the force. So very quickly we've got this here. So we know that these two characters here will balance out that seesaw because they each produce the same bending moment. Because we've got the same value here. This one is double the force and half the moment arm of the other athlete. So we're going to have a balance out. So that's what we're talking about when we're talking about moments here is that bending force is the current. So if we look at our ACL, we've just seen people go through and get injured. And when they get injured, we saw that we had the knee tends to collapse in, which is what we call a valgus load or an abduction load of the knee. And this is some cataberic work where we can go through and they went through and they actually loaded the ACL. This worked by Markov in 1995 and they loaded the knee with an anterior drawer load. So this is this black line coming through here where we pulled on the quadriceps tendon, which slightly pulls the tibia forward, which causes an anterior drawer load on the ACL. What these other lines here is the combination and the addition of an additional load. So we can see here that below about 10 degrees of knee selection. So we get a huge increase in the load on the ACL when we apply an internal rotation load. Again, with our barus load, so this is when our ankle is pulled in. So we're putting a barus moment or an abduction moment on. We can see that we see an increase in our ACL load, again, below about 10 degrees of knee selection. If we look at our valgus load from about 10 degrees of knee selection through to, you know, right through, we see an increase in our anterior drawer. If we apply this valgus load, we really see an increase in the load on the ACL. And really the big loads are these valgus and internal rotation. These are the ones that have been shown to be dangerous when we look at this cateveric work and are the lines to where we see the knee collapse. So when we looked at all of those, we saw the knee collapse inwards and down. What we also know is that the ACL can be supported by the muscles across the knee. So all of the muscles across the knee, we talk about our quadriceps as being extensors. But if you think about our quadriceps, if we break them down to our valgus lateralis, it actually inserts on the lateral aspect of the catella. So it's going to have a lateral force. It will produce an abduction moment on the knee. Similarly with our valgus medialis inserts onto the medial aspect of the catella, so it's going to produce a barus moment on the knee. So if I contract all of my medial muscles, I'm actually going to counter out an external valgus load to something which is forcing me into a valgus position. So our muscles, yes, our quadriceps are extensors, our hamstrings and flexors, but they also have the ability, because of where their tendons insert relative to the axis of rotation, which is going to create that moment, they can produce barus and valgus and internal and external rotation moments, which allows them to support. And we can look at that through our total activation, how much muscles are occurring, their pro contraction and also our muscle strength can you just play with it. So we've gone through, we've seen how people get injured, we've looked at the loading and now we can think about, well, why do we think that that might be a bad condition? So we saw that when people got injured, they tended to look like this with a wide foot placement a long way away from the midline. So we remember back to our moment, it was our force. And in this case, we can assume our force is our mass, modified bar of gravity coming down through here. So in both of these athletes, it's the same mass, the same person. But we can see that we have a different moment arm. When our foot's enclosed, we have a small moment arm, so the force is coming down not too far away from the middle aspect of the knee. And in this one, we have a much larger moment arm. So what that results in is a much bigger abduction or abrogate moment in this wide foot placement. And we can go through and test this. And this is what we did. We've gone through and we got people to do a whole pile of wacky side steps that they came in, run forward, do a side step. That's this normal side step here. And we then got them to throw their torso in the opposite direction of travel, in the same direction of travel to rotate their torso around. So their right shoulder was back if they were heading to the left. We've got them to flex their knee. We've got them to have their knees straight. We've got them to turn their foot in, turn their foot out. Foot has got close wide, close, and also put their foot as far away as they can and do the side step. And what we see is that when your torso is leaning over and when your foot's wide, you see an increase in the abduction moment or the abrogate moment. So we know that the abrogate moment increases the load in the ACL. We know that people who got injured had their foot out a long way. And now when we measure that in a lab, we can see that those who have a wide foot placement have a bigger abrogate load. So it's all sort of starting to align that we've got this wide foot placement. Of course, it's a high load of the knee. It's causing a knee load, which loads the ACL. We also see that placing the foot wide also increases the internal rotation moment at the knee. Again, internal rotation moments, particularly when the knee is straight, leads to a higher abrogate load. So again, this foot wide is a really bad position because it mostly increases your abrogate force. And it also increases your internal rotation moment at the knee. So now we've got a good handle that there seems to be a technique relationship to how we get injured. So we want to develop some preventative measures. We want to stop these guys getting injured. So we've got two options from a biomechanical perspective. We can reduce our loading or we can increase our support. So we want to do one of these. So where does sort of the biomechanics come in? What do we want to do? Well, let's go back to this. We worked out that we've got the same athlete, which means that they have the same mass. But we've got different moment arms, which result in different talks. So if I can move an athlete from having a technique that looks like this to a technique that looks like this, maybe I can reduce my force. So I've got a prevention measure. Let's change the technique. Let's take people away from the high risk, high load technique to a reduced loading environment. So we've come up with a theory. We've gone through, we've developed prevention measure. We think this is going to work. So now we need to some and test it in an ideal and ideal conditions in a scientific evaluation. Now the great thing with biomechanics and in testing this is that we can use a much smaller cohort to go and test out to see if our preventative measures work. If I'm trying to do actual epidemiology studies where I go through and I apply this to a large cohort and I track to see if they get injured over time, I need 200, 300, 500 people. To test this in the lab, I can do it with 20. So it's a great way to sort of test. I've got my risk factors. I've established what my risk factors are in here. And often these risk factors are things that we can measure in biomechanics. It's a force. It's muscle activation. So we can measure these risk factors. We've identified them. We can measure them. So we can apply our intervention and see, does it change the risk factors? So the risk factors that we had were a large valve that's in a large internal rotation moment. So we've gone through and we were trying to get people to avoid these high loading techniques. So these are the techniques, these three from the first paper that we were talking about and this one from the literature which is to increase knee collection. And we try to get athletes to do all of these. To bring their trunk more upright as it is a side step. To not rotate their body. To bend their knee a little bit more at foot contact. And also to bring their foot in closer. And we can see that we weren't really great at successful at getting their knee flexed. But we could bring the foot closer to the midline. So the foot is not much. It's only two centimetres as a whole population. So the foot's come a little bit closer. And we've also got the torso to be more upright, particularly during a planned side step. So during this task they came through and were either told you're doing a side step or just before they reached a force plate they were told do a side step, do a run, do a crossover cut for the change to go the other direction. Which is just to try and mimic that unplanned scenario that you see in the field. So particularly when we had a planned side step we see a reduction. Oh wait, a reduction in our torso lateral flexion. Great. We can change techniques. I would hope we can. Particularly any of us who have been involved in coaching. That's what we're trying to do is change techniques. So great. We can do that. It was done with video feedback. Those guys got to watch them. Watch themselves perform. Cues in the ground. So all of the stuff that we get from our motor learning. And what we found was that we can reduce the valgus moment by about 30% just by bringing the foot in about two centimeters on average and also keeping the torso upright. So from an injury prevention perspective this technique appears to be successful. And when you go through and look at injury prevention programs which are now rolled out more broadly you see this technique modification being included alongside a lot of the technique modification you see in landing about getting the knee, keeping the knee out in that position out over the small little toe. So that's really that the main role that Biomechanics has in this space but just to sort of finish up the injury prevention really the next step is about and ISPS is very much about trying to get things into coaches and getting coaches to actually apply stuff which is really where this next step is which is to think about where we want to apply this intervention and to make sure that it's going to work. Your environment where you're going to want to put this intervention in it's going to make a huge difference to the population on to what you actually do and then we can go to evaluate it. So some of the things you need to think about when you put an intervention together is sort of the nature of the sport. If you have a contact sport an obvious solution to a number of the injuries is to take away the contact. There's a lot of debate at the moment around tackling in rugby union. I know in the UK there's been some letters from some very influential people saying that there should be no contact in Schoolboys Rugby Union. I've seen some similar sort of arguments made here in Australia. But that's what the sport is. So how do we modify a lot of the work that was done recently and would demonstrate the last World Cup to reduce the tackle height and to have mandated frameworks around yellow cards which led out by the rugby science network and over in South Africa as well to basically enforce the rules but understand the fine mechanics and understanding how people are actually getting injured. That's a good example there. Now the level of the target cohort this might be a great intervention for a professional team probably not so good for your under 10 soccer team that you're coaching on the weekend because you don't have all this equipment floating around and you're never going to have it. How invasive is the intervention? We can talk about changing people's curangles of their hips to reduce the alignment, to get better alignment in the knees but I don't know many people who are going to go and have that surgery just to reduce the risk of ACL injury. So the surgery is probably more invasive than an ACL injury. You also need to think about what players want. If anyone's ever heard of the FIFA 11 plus soccer program it failed miserably the first time because it was 11 static exercises that didn't progress. If you think about anyone who plays sport the first thing you want to do when you get to the field is to get a ball and to score. So we need to make sure that your players are moving around that they've got the ball, that they interact and move around and also progress and you also again this comes down to that the level of the target cohort what sort of things club have access to. Just before we go, let's have one more example of how we can use this and this is an intervention that's slightly different we can actually change the rules to the game but without really changing the nature of the sport. So rules and nature are not always exactly the same. So if anyone's ever seen the AFL the game traditionally starts with the ball being bounced in the middle and the two guys, two biggest guys in the team pretty much run up and try and tap the ball to their own advantage. What the AFL was finding is that from 98 to 2004 there was an explosion in PCL injuries occurring at this centre bounce when the game was being restarted. And what they were looking at is that the rules at the time said that the guys could run anywhere from inside a 50-metre box so they had to start one side or the other so two guys weighing 100kg could sprint a detailer at 25kg jump up within these led boards. Probably not the best idea when you consider that the ideology of a PCL injury is the tibial impact force putting rapid posterior shift and PCL rupture. So you don't really want two guys banging their tibias into tolerable speed. Now, we all know that when two guys make contact for impact momentum... sorry, impulse momentum relationship says that the quicker we have to change our momentum the bigger the impulse is going to be and our momentum change is related to both how big the guys are and how fast they're travelling. So we're not going to make the guys any lighter in fact they've gotten heavier since then but we can actually reduce their speed and the way that the speed was reduced was to actually introduce a 5-metre circle sorry, 10-metre circle so the guys instead of running from this line back here which is 25 metres away only had 5 metres to accelerate that results in a reduction in velocity and therefore a reduction in that peak force when they make contact. Does it work? This is great because the ASL keeps great injury data so if you ever want some injury data to look at how things change in interventions come here and we can see that when the rule was introduced before the 2006 season the number of centre-bound PCL injuries fell and completely disappeared and hasn't gone back up yet and that's still the rule that's being used. So what the rule changes introduced but it doesn't really change the nature it's still two big guys jumping up and competing for the ball they just do it from 10 metres away as opposed to 25 metres away and we don't change. Now the final thing to remember before we sort of stop talking about injuries is that it doesn't really matter how good we are at injury prevention there is no way that we can stop all injuries there is always something that's going to happen that is beyond any sort of prevention that we can introduce other than sitting in our own rooms and doing nothing. Thanks very much guys. Okay, thank you. So all that's left for me to say is a huge thank you to Alastair for kicking us off on week one of the Sports Biomechanics lecture series and I'm sure you'll all agree that was excellent and I really enjoyed it. If anyone has any more questions then please kind of use the hashtag on Twitter so hashtag sportsbiomels and we will be keeping an eye out for that but I can now announce kind of the schedule for the next two weeks we've got both myself and Dr Paul Felton focusing on cricket biomechanics next week which will be both bowling so fast bowling and spin bowling followed later on in the day by batting biomechanics and then there's a couple of really interesting talks the week after which on Tuesday the 7th is Johans with long jump with the sports prosthesis and then on the Friday we have Walter with running footwear and the two-hour marathon so keep an eye out for those all the talks will be on YouTube and will be sharing links on social media in the coming days. Thank you.