Equestrian Rider Biomechanics | Dr Céleste Wilkins

Hello and welcome back to the Sports Biomechanics lecture series. And today, so our first of two talks today, I'm joined by Celeste Wilkins who is a PhD student at Hertfordshire University and this is another really interesting topic that kind of fascinates me because I wouldn't know where to start with this one. But Celeste is studying the coordination between equestrian riders and the horse. And as her Twitter bio says, no riders don't just sit there. So I'm quite looking forward to finding out what the riders actually do and learning a little bit more about equestrian biomechanics. So over to you. Thank you Celeste. Hi everybody. I am finishing up my PhD at Hertfordshire University and my research area of interest is equestrian rider biomechanics. And like Stuart said, I'm looking at the coordination between horse and rider. And I'm going to talk you through a little bit about how we collect the data, some interesting analyses that we use and some really cool future directions that we have in equestrian sport. But I realise that many of you have never had any exposure to equestrian riders or the study of biomechanics in equestrian riders. So I'm going to talk in general terms, but I'm also going to refer you to a few key references should you wish to delve a little bit deeper. So equestrian sport is really part of the culture in the UK where I'm based. But it really came to the fore during the 2012 Olympics when Team GB took home five medals in equestrianism. And arguably the stars of the show were Charlotte Dujardin, pictured here, and her horse Vellegro. They won individual and team gold for Team GB and they compete in a sport called dressage. Dressage is a little bit like the floor routine in gymnastics. So the rider pilots the horse around the arena doing a series of transitions in different gates and within the gate. Some changes of direction and different movements that are all judged by a panel. And they're really looking for the rider to be very highly coordinated with the horse and an appearance of flawless simplicity, which is very hard to achieve in practice. Horses like Vellegro are worth millions. So it's like Charlotte sitting on the equivalent of an F1 car. Now, other than dressage in the Olympics, we also have show jumping, which is where the rider pilots the horse around a course of obstacles that at the Olympic level can range in height up to 1 meter 60. And we have eventing, which is the triathlon of equestrian sport. And it involves a phase of dressage, show jumping and cross country, which is over some natural obstacles on a longer natural terrain course. And so the horse can have a career that spans multiple riders. It takes about 10 years to get a horse up to that Olympic level. And really the career killer for a horse can be orthopedic injuries. The horse can't necessarily tell us with words any sort of underlying issues that could cause a problem. So we rely a lot on gait analysis with our horses to understand how their performance may be affected and also monitor them for any changes in particularly the asymmetry of their gait. So gait analysis in the horse is very similar to what you would do with your human participants. However, we have a few challenges that are very specific to horses. For example, the average stride length of a full sized horse can be up to 326 centimeters in trot. And we like to look at successive strides in the horse when we're measuring their gait. So we would require at least a 15 meter track if we're going to look at five strides. And that requires a lot of cameras and wires and tripods. And we're working in indoor riding halls that don't necessarily have the setup that we would like for motion capture. We're going to use the gold standard of biomechanical analysis. And so we're setting up these tripods and these wires, but we also have horses that are quite fit and highly strung and we have to consider their health and safety. So it can be quite a challenge. Thankfully, we have these inertial measurement units that have been validated against motion capture for use in the horse. And these look at the symmetry of the horse's gait so we can monitor them for signs of lameness, which is an orthopedic problem in the horse. And these really give us a chance to assess a lot of horses in the field, both ridden and trotting in hand without a rider. But they cause a bit of a debate within our equestrian community because this new level of precision has never been seen before. So traditionally, we'd have a practitioner, whether that be a vet or somebody who has been highly trained to assess the level of symmetry in the horse's gait. But now we have these IMUs that give us really precise information about the rotations of, say, the horse's pelvis. And now practitioners have to decide what level of asymmetry is actually clinically relevant and how to use IMUs or sensors in the field and whether they should be used in practice. So there's two really good references there that delve into that debate. And I could see it continuing in the future. At Heart Pre, we're pretty lucky. We have some outstanding facilities. We have arenas for riding as well as our stables and our equine therapy center where we look at both horses and riders. So if we want to standardize the incline or the speed of our horses when we're doing research, we can use the high-speed treadmill. And as you can see, we can set up our cameras much easier in this setting than in a riding arena. And it's excellent. It's an excellent tool for both our research side and our strength and conditioning of our horses. My supervisor, Dr. Catherine Nankervis, she looks at the kinematics of horses on the high-speed treadmill. And we also have a water treadmill, which we use for conditioning and research. And she's used motion capture and IMUs in that setting as well, which has led to some pretty cool studies. So obviously, the horse plays a huge role in the outcomes of performance in competition. But there are a lot of international research groups that are looking at the rider as well. And we can lump those studies into several categories, such as the characteristics of injury. If you fall off a horse, you have a high chance of sustaining an acute head injury. These are the most common in falls. And so there's an emerging body of research that's looking at riders and jockeys, how they fall off the horse, and also testing the safety equipment from a biomechanics perspective. So as you can see, this rider here competing in a venting dressage is not wearing a helmet. And helmets are quite common in the equestrian sport, but not necessarily taken up by all riders, particularly in competition. Also, chronic back pain is quite prevalent in riders. And there have been a few studies looking at the potential mechanisms of injury there. When it comes to coaching and progression in sport, there's a big question, how do you become an elite rider? From a biomechanics perspective, we've looked at the difference between a novice or a non-rider and an elite rider, and the differences within the kinematics and also muscle activation patterns that the riders have that make them, say, an elite rider. And then, of course, we're riding a moving animal, and we have to consider the horse's welfare. So there have been several studies that have looked at rain pressure. So the rains are the leather strap that's attached to the metal bit in the horse's mouth, and that bit rests on very sensitive gum tissue. So rain pressure is very relevant for the welfare of the horse, but also the saddle pressure. So the rider applies pressure with their seat in the saddle, and that can influence their kinematics as well of the horse. And then use of different types of equipment, training equipment, and interventions is quite commonly studied as well. But my area of particular interest is performance-based. So we're looking for quantitative performance indicators to use as benchmarks for the rider and to be able to assess their performance with a higher degree of precision than we have previously. So when we talk about technique in the rider, we have to stay on the horse first and foremost. That's the prerequisite to riding, of course. But once you're able to stay stable on the horse through the repetitive movement of their gait, then you learn to use your hands, your seat pressure, and your legs independently and together to cue the horse to move in different directions, to speed up, to slow down, etc. And that's really the hallmark of a good rider, that they're able to independently use different parts of their body to train and cue the horse. But in terms of their performance, we don't have a standard of what that should look like other than the vertical alignment of the rider's ear, shoulder, hip, and heel. And that places the rider in a quite stable position. If you think about it, it places their center of mass within the limits of their base of support. If you take that horse out from under that rider in that picture, you would have a rider that would be kind of crouching on the ground. So it is a stable position. And that's the position that's traditionally prescribed by coaching manuals, such as the British Horse Society. When we look at the studies, the riders are more likely to be classified as advanced by a qualified judge if they have their trunk closer to the vertical. So judges like this position. And this is a trunk orientation that's developed with instruction. So Kang looked at riders when they had never ridden and up to 24 weeks of tuition twice a week and found that as their riding tuition progressed, they were able to straighten up and sit closer to the vertical. But the problem is that this is based on a static image of the rider. So it doesn't actually indicate how the rider is absorbing the motion or following the motion of the horse. For example, an excellent study by Lagarde in 2005 showed that a recreational rider compared to a professional counterpart was able to achieve a consistent trunk to vertical angle. So they're riding along and sitting trot and their angle was quite consistent. However, that pattern was not sustainable. After a few strides, they had a degenerated movement pattern and descended into a bit of chaos. Whereas the professional rider oscillated in time, so moved their trunk angle to absorb that movement of the horse. And riders do deviate from this position. So their angles do change over the course of the horse's stride. And that's been shown in several studies, like the one by Shills and Lovett. So there's much more to the story than just that vertical alignment of ear, shoulder, hip and heel. And that's really what we're trying to get to with all of our rider biomechanics studies. Another key buzzword in equestrian sport is the rider's pelvis. So we're really interested in understanding how this movement interface between horse and rider. So the rider's lumbopelvic hip region absorbs the movement of the horse and allows them to remain stable so that ultimately their hands and legs can also be stable. As you can see in these GIFs, there's a lot of movement in that area and there is a potential implication for rider back pain. So we're starting to drill down on that issue and assess it and treat our riders based on what we know. We know that elite riders follow the movement of the horse by rotating their pelvis. And in the sagittal plane, like you can see side on with these riders, the rider follows a pitching motion, so forward and back, that resonates with the horse's stride. So two beats per stride and trot. So the rider pitches forward and back twice every stride. Riders may control the angle of their pelvis in the anterior-posterior direction to influence the horse's stride. So riders may tip forward or backwards and hold their pelvis in a way that directs their seat pressure to cue the horse to shorten their stride or what we call collection, where the horse has a much more elevated stride. And that's what you're seeing here in these dressage horses. One study by Munns in 2014 found that professional riders may tilt more anteriorly, significantly more so than beginners in walk, trot and canter. So there's really a question as to what kind of pelvic tilt is necessary for the rider. Actually, recently one of our Olympic dressage riders said on social media that her saddle held her pelvis in a more neutral position, which was more beneficial for the connection between horse and rider. But the research hasn't quite delved into what position your pelvis must be in and whether that's a facet of elite technique. And so my first PhD study wanted to look at these preconceived notions of rider's pelvis, because it is that crucial movement interface between horse and rider, and how you assess it. So I wanted to see whether you could assess the rider's posture statically. So whether if they're sitting in the saddle at halt, whether any of the information that we can get about their pelvis would correspond into the movement condition. And also, if it is true that you develop your seat through years and years of riding practice, whether there was going to be any sort of difference between a top level rider and somebody who was just starting their competition. So to do that, I looked at riders on our race with riding simulator. So I recruited 35 dressage riders, and they had to have results at the international level, which is the FBI levels, or British dressage competitions, they're all females. And they were assessed using qualisys motion capture on the Racewood Eventing Simulator in Watt, Trott and Cantor. And the Racewood Eventing Simulator is a really high tech piece of kit, we call ours Margaret. And she moves in three dimensions and simulates the movement of a horse's trunk. Now, a lot of riders get on and say, well, this is not exactly like my horse. But it does allow us to expose all of our riders and our studies to the same frequency and amplitude of oscillations and cut down the variability that would be given by the horse. And it allows us to set up our motion capture cameras and collect data all day long and not have to worry about horses being tired or having every rider ride every course and recruiting different types of horses. So it's a really, really good piece of kit for research. And it means that we can develop our analysis procedures and our protocols in a simulation environment, just like you would say with a treadmill or a bike. And then once we're ready to expose our riders to live horses, once we've developed our experiments as thoroughly as possible, then we recruit horses. So it's from a welfare perspective, it's actually quite a good piece of kit. So this is what the rider looks like in our motion capture software. And this is a sitting trot. And this pink segment here, the rider's pelvis is what I analysed in the sagittal plane. So looking at the pitch, and I took the minimum maximum range of motion and mean tilt over the course of an oscillation cycle. So it's all split into the cycles that were given by the vertical displacement of the riding simulator. And so I tested the effect of gait and the effect of competition level on mean pelvic tilt at halt and during motion. And riders were split into their competition level categories. So novice was the first three levels of British dressage. Intermediate, the subsequent three levels, and elite, everybody competing at the elite levels of the sport, so the international levels, including the Olympic level of Grand Prix. And what you can see here in this bar chart is that at halt, there was no pelvic posture, whether that's anterior, so tilted forward, neutral, so front and back were equal, and posterior, so tilted backwards. There was no posture that was more indicative necessarily, or statistically so, in any competition level. So that was quite interesting. And then when we compared the halt tilt to the dynamic tilt in walk, trot and canter, we didn't find any correlation between halt and dynamic tilt. Actually, all riders, regardless of their competition level, tilted more significantly backwards or posterior in trot and canter than in walk, which seems to suggest that there's a dynamic strategy going on. That was a little bit different than what Munns found. So they found more anterior tilts. And there was no interaction between competition level and mean pelvic tilt. So regardless of whether you were competing at Grand Prix or the first level of British dressage, which is called prelim, you might be doing the same thing. So therefore, I would suggest that we should be assessing our riders dynamically, rather than looking at a static image of the rider, and using single subject designs where appropriate. So trying to figure out what that individual rider is doing, rather than saying that all elite riders are doing this, because there could be differences between those elite riders that would be very interesting to unpick. So if we want to have a dynamic analysis of the rider, we need to really have a goal in mind. So if you see these three riders, this is in our motion capture software. And if you're a biomechanist looking at this, you could see many, many different possibilities in terms of the analysis. So if we think about a goal for equestrian analysis, we think back to what the judge is looking for. In dressage, it's a judge sport. So we want to judge the rider performance in a biomechanics way on what that outcome, what it means for their outcoming performance. One of the key judged qualities of the performance is the level of coordination between horse and rider. And colloquially, we call this harmony between horse and rider. And so if we're going to derive something that is useful for riders and judges, harmony looks like a very, very good prospect. And there have been a few studies that have looked at the level of coordination between horse and rider. And typically, these are using analysis techniques from the dynamic systems theory approach. So using variables such as the relative phase between horse and rider and segmentally as well between the rider to come to a conclusion about what's important when it comes to the coordination between horse and rider. And these studies have used only a few participants. And so there's definitely more work to be done here. But these early indications are telling us that as the rider is more progressed in their experience level, that there is increased coordination between horse and rider. And this is for with the relative phase analysis. Also that riders that are more experienced and more coordinated with the horse induce less variability on the horse's gait. And this is something that we're really looking for in the dressage competition. So rhythm and regularity are these judged qualities of the dressage competition. And so anything that the rider can do to decrease the variability of the horse's gait is definitely a positive. Also riders that have greater coordination with the as described by the relative phase, they were judged more beneficially by a dressage judge. So they got higher scores. And that's, again, something that we're looking to use as a performance indicator in equestrian sport. When we look at the segmental relative phase analysis of the rider, more experienced riders had greater phase matching with their elbow to the horse's movement. And that seems to indicate that their reign lengths or their contact with the horse's fit would be more consistent throughout the stride. And there was also an interesting ankle strategy that a professional rider showed in relation to the beginner rider. So they were absorbing the motion through the flexion and extension of their ankle. And that meant that they were able to keep more of their segments in phase with the horse. So rather than saying that all riders need to be aligned from ear, shoulder, hip, and heel, which you can see in these riders who are all competing at Grand Prix level, which is the Olympic level, we can start to have more indicative analysis of the rider that speaks to our performance goals rather than just applying a template and looking at angles. And so that's what we're really looking to do, offer some kind of analysis that can influence how the rider is being coached, any programs that they have off the horse that might influence the level of coordination between horse and rider, and how riders progress through their coaching levels or their riding levels in a much more dynamic way that takes into account the self-organization of the system of horse and rider. And we're also looking at some indications of what variability means for horse and rider. So all of these riders competing at Grand Prix are doing things a little bit differently. And we're looking at measures that might take that into account and describe that. And its impacts on the rider's performance. So right now we're looking at this level of coordination on the riding simulator and developing our analysis procedures, which if anybody has undertaken any dynamic systems analysis of the rider or of other sports, it's quite a complex process that involves a lot of coding and is fun, but still at the same time, quite complex. So we're developing this on the riding simulator and what we're trying to do is then understand what variables we need to be looking out for so that we can take that into the field. But like I said previously, analyzing the rider in the field is no easy task and having enough cameras, having wires buried under surface, all of these things need to be taken into consideration. And of course, while we do have IMU suits and things that are available to analyze humans in the field, these don't necessarily tell us what we need for the rider or what we don't know yet. So there's a lot of more testing and analysis that needs to go into our procedures in order to only recruit the riders and horses when we're absolutely ready for action. But as you can see here, it is a lot of fun to use our international arena, which has great access to power and all the facilities that we need to analyze horse and rider. And at Hertford, we're also looking at different student projects. So this was a really fun project that we did with the student looking at jumping kinematics and it makes it a great way to make biomechanics accessible to a population that might not be as interested. So equestrian science or equine science are very practical minded. And when you bring it to the horse or when you explain things with reference to the horse, which our students know very well, then you can start to get a better idea of exactly what's going on. And we're making more scientifically oriented equestrian practitioners, which is not a bad thing at all. So in conclusion, equestrian sport involves a dynamic interaction between horse and rider and we can analyze both horse and rider in the field. More information is available all the time, but we have to analyze this information critically and think what is actually necessary to report back to our coaches and riders and how we can make that information accessible and relevant to improve safety, to improve performance, to support horse welfare. And empower coaches. There's a lot of coaching research also going on looking at fusing biomechanics and particular dynamic systems with how riders are coached. And that is an absolutely massive development for our sport too. Rider performance indicators need to be relevant to performance. So if you give a rider a report, it needs to tell them things that they can understand and that they can use within their practice. And that's true for any sport, but at the equestrian level, we're only at really the start of our journey exploring what variables really impact performance. So the research to come in coming years is going to influence that development. And at Hercury anyway, we are really poised to be able to do a lot of research with horses and riders. So that has been a really great thing in my PhD anyway. I'd like to acknowledge my supervisors. I have a great team including Dr. Catherine Nankovic who keeps me on track with horses and riders. That's her focus. Dr. Lawrence Prothero who's a biomechanist and Dr. Stephen Draper who looks at the physiology of runners and has really contributed a lot to this project. So thank you very much. Okay, thanks Celeste. That was really interesting. I think so you alluded to it yourself, it's always really good when the research poses even more questions. So kind of watching that and making a few notes, but kind of I kept coming up with questions and more questions and more questions, which I think is always positive. Yes, one of the things I was interested in was the difference when you talk about pelvic tilt and the fact that you've got both anterior, posterior and intermediate or neutral tilt, but all competition levels. I was, and I know nothing about equestrian, I'll admit, but I was interested in that and saying if it doesn't seem that it's something to be corrected, so it's not necessarily the case that the elite do one thing, so we should try and make everyone do that. What's the application? Are there any, if you can identify that someone is anteriorly or more posteriorly tilted at the pelvis, would you then put slightly different implementations and interventions in place for those people? Well, there are some practitioners that would argue that yes, it is very relevant and as it does influence the spinal curve, yeah, possibly there is some effect of the pelvic tilt on potential back pain. However, I think that it really needs a more full body approach. So if the pelvis is tilted anteriorly, what does that mean for the rest of the rider's body? I think that riders should look at their body as a system, as a whole, and analyze it dynamically. So at what point in the stride is the rider anterior or posterior or neutral? Because the rider is moving, so if it's a mean pelvic tilt, what does that mean? And I think we're getting closer, but I don't think that we have all the answers with that yet. Okay. Yeah. I think when you say about looking at the whole system and other things that could play a factor, again, I'm very kind of unknowledgeable in this topic, but I was wondering whether limb length or other joint angles could play any role. So just when you have the three kind of gifts of the different riders, I was looking at it and thinking whether people with longer legs or shorter legs leading to kind of greater or lesser knee angles or hip angles, whether that would play any role on what kind of pelvic tilt they were displaying. Yeah, definitely. And we run rider performance clinics at Heartfree and we screen all of our academy riders. So we have an equine academy where riders can bring their horses and compete while doing their university studies at Heartfree. And that is limb length inequalities are something that we look at in those screenings. So I don't know that we have definitive answers as how it influences the rider, but also bear in mind that the rider can choose their stirrup length. So their feet are in the stirrup and they can choose if they want to have shorter or longer stirrups. So that definitely will have an impact on how they're using their legs to follow the horse's movement. There's some really interesting actually biomechanical models of the rider and the leg is a key component of that system that allows them to be able to follow the movement of the horse. But of course, the leg is going to be impacted in its usability by the length of stirrup and that's going to affect the ankle and the knee angles and the hip angles. So there's probably a lot more to unpack there in terms of both the symmetry of the rider and the length of the stirrup that that rider would choose or is instructed to choose, which would make for some pretty cool studies, I think. Yeah, I agree. I think as we said earlier, lots more questions, but that's definitely a positive thing, I think, at this stage. Yeah, the other thing kind of I was really interested in is the actual simulator, which looks like really exciting. Does, just out of interest, is there any variability in, I think you mentioned the frequency and amplitude of the oscillations, is that the same every cycle or does it vary from cycle to cycle? It is the same every cycle within each gait or each simulated gait. So there's walk, trot and canter and then there's three different frequencies of walk, trot and canter, frequency and amplitude. So you can have collected, medium and extended and that would simulate what the horse would be asked to do as well. But I think that the question of variability is a very interesting one and shouldn't be discounted. I think also, though, that that would be a great thing to analyse with the live horses rather than the simulator. I think the simulator has its place, but you can't beat going out into the field and looking at what kind of variability the horse throws up as well. Yeah, definitely. I think, yeah, the whole idea of functional variability as well and saying, is there anything that the elite riders are able to do to cope with that variability that lower level riders maybe aren't. But yeah, it's just an interesting thought and I think, yeah, the last, probably last question for me, I've got a lot of notes here, but you mentioned in that answer about the walk, trot and canter, it was interesting that, if I remember this correctly, all levels of riders had a more posterior pelvic tilt in the trot and canter than they did in the walk. I think that was correct. Do you have any ideas or any guesses as to why that might be or why that pattern exists? Well, there could be many factors that would influence it. Within the level, the riders had different patterns, so the mean tells us that all the riders within the competition levels were more posterior, but within that, there were some riders that went interior in walk, neutral in trot, and then posterior in canter, so there's probably a lot to unpick there as well. But typically, I guess the riders were trying to get behind the movement or follow the movement with a more posterior tilt is what I would say as a rider myself, but I think that poses a lot of interesting follow-up questions for the data that we're looking to explore as well. Yeah, thanks. I think that's brilliant. It keeps coming back to more questions and that's where I always get excited in my own research where, rather than just answering the question and then kind of job done, it's always good when you can see a path for both yourself and others in the future in various different directions people can choose to go down. Definitely, and I think also the fact that equestrian is getting more exposure in the water sports biomechanics community means that we can have questions from people who don't know horses and that always throws up the most interesting things that I'd never thought of, so it's only a bonus. Yeah, and I think, personally, I definitely fall into the category of people who don't know horses, but yeah, that was really, really interesting, thank you, and kind of, yeah, a really novel topic and I think I definitely, as I said at the start, we said no, the riders don't just sit there. I think it's definitely increased my knowledge of what the riders do but also the coordination between rider and horse is a really interesting topic. I think, could you just go on to your next slide, please? Yeah, so just as a final thing for kind of people watching, if you've got any questions then either use the comments section on YouTube or get in touch on Twitter with either Celeste or myself or the hashtag at the bottom of the screen and we'll try and get some answers for you where we can, but don't forget there is another talk later today on rugby place kicking biomechanics which should be another interesting novel topic. The final thing for me is just a really huge thank you to Celeste because, as I keep saying, that was a really interesting topic and something where I feel like I've gone from zero knowledge at all to actually having a bit of knowledge and a lot of interesting questions. So yeah, thanks very much for that. Thank you.