Equine Mechanics

Author: Sian Townson

  • A scientist’s perspective on scientific evidence.

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    When I started as a scientist publication was all, it still is. I now understand though that if I write a paper, it will be published. Maybe not in my first choice of journal, but however good or bad it is, there is somewhere that will publish it. Now journals accept papers on the same day or the day after submission. Do we really think they’re getting peer reviewed? When I want to know more about a condition, I don’t just Google something I look at the academic literature, try and find out what the evidence suggests, but is that also just someone’s opinion now?

    When I was a young, naive PhD student I was slightly shocked that journals asked me to suggest my own reviewers. Not that naive, I just named the people I was currently sleeping with, but still it did seem to lack a little subjectivity. Fast-forward a decade or two and the profit-based world of publication has exploded.  Editors need to get papers in and out again through the pipeline. Authors need to get those manuscripts off their desks and on their CVs and grant reports. Quantity over quality every time. I have now written papers which are essentially just my opinion, waffling away, and they’re published not in journals on discourse but scientific journals that lend my thoughts and air of peer-reviewed authority. These are no longer my thoughts, these are now evidence-based facts.

    So, if you’re reading up on a clinical condition, what should you look for?

    1.Randomized Controlled Trials (RCT)

    Just having collected some data and analysed some statistics doesn’t make it good evidence. If I flip a coin and it lands on heads four times in a row, is that a rare and noteworthy event? No, it’s a sign of randomness. If I flipped a coin and it neatly alternated between heads and tails, now that would be noteworthy. I once co-wrote a paper with an amazing statistician, demonstrating how the statistics in one of my previous papers were a misleading mistake. No one would publish it. Randomized controlled trials are the best we can do for looking for actual significance.

    2. Cochrane reviews.

    These are a special type of review of the existing papers. They collect together eligible studies into a meta-study, telling you what the balance of the evidence says. These try to include only peer-reviewed papers that have a rigorous method and so collect together a much larger, combined subject group. They use some fairly robust statistics, and are a hell of a lot more accurate than just trying to read and counter-balance all the papers yourself, by eye.

    3. A bit of time for peer review

    Most published manuscripts have date of submission and date of acceptance stamped on them. I used to think of this as a badge of shame: if it takes me a year to get my paper out everyone knows that. Oh, how the world changes. Look for something that’s obviously been through a  discussion process, preferably a long one, not just same day/next day acceptance. Publication bias means it’s actually much harder and slower to publish a paper with a negative result – “we looked but actually it wasn’t there”, “this doesn’t work” – or a paper that goes against the mainstream. Doesn’t make it a bad paper, on the contrary, unexpectedly negative findings can often be the important ones.

    4. Big name journals.

    There’s a lot to be said about impact factors and how to judge a good journal which doesn’t really belong here. Fact remains, how often a  journal is cited and how often a paper is cited says a lot about how seriously academics are taking any paper. Of course it doesn’t tell you whether people are agreeing or disagreeing with it, but any academic mention is still more reassuring than a paper that is politely ignored by the scientific community. Those lesser-known ones, in the journals with the ridiculous names, those are the ones that you need to politely ignore too. Scientists don’t actually ignore papers just because they disagree – it doesn’t take a second to write “Contrary to the findings of Blogg and Blogg (2015), we showed…” Having someone to disprove makes your paper more publishable – you’re now showing something that actually needed to be shown.

    5. Not conference papers

    Any collection of papers that has a nice holiday attached a.k.a. conference papers, is going to get our slightly less completed thoughts. Conference papers are often published in mainstream journals and look like full papers on your CV, but depending on your field it’s fairly hard to get a conference paper rejected. They only need preliminary findings as these should be the cutting edge of your ongoing research, your chance to tell the field what you’re currently working on and get the feedback and awkward questions that’ll make the next round of tests and the final full paper a far more reliable affair. I for one am on the committee of a lot of the conferences I want to go to, and at the Keynote career stage. This means that I often get asked to submit a paper for a talk that I’ve already been asked to give. You can peer-review that all you like, it’s already been accepted.

    These days scientific publication falls under the more general category of things we read on the internet  – where even if it’s an intelligent person’s best guess at the time it’s not necessarily true. That’s OK, it never was – scientists don’t believe in facts, they believe in best current theory and convergence towards a solution. Just remember that scientific papers are not the protected species that they used to be, and should be read with the scepticism and critical thinking that allows the good ones to shine.

  • Isn’t it just a horse? Ode to a Hobo.

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    Before and whilst I had Rossvean (above) I must have had 20 or 30 other horses. I was only a kid but I rode for competition yards, I rode for private owners, I rode for myself. Rossvean was my first real rescue horse, others were more scopey and more straightforward but he had a brave heart and I trusted him completely. Ross’ was the mane I cried into when my parents left. Eventually I sold him and my heart broke. I found the next horse, and the next. I asked my trainer for help as something about these horses just did not work any more. She looked at me very sternly and explained that “there’s never going to be another Rossvean”.

    I have an excellent memory, I don’t forget words, sometimes I wish I could. The feeling of being metaphorically punched never left me either. I sold up and I quit. For over a decade I quit. Eventually I started to ride again, very occasionally and only for other people. Don’t you miss it? They’d ask. Every day, I’d say. Then one day I fell in love with a horse. Hobo was exactly what I look for, a horse worth coming out of retirement for. Big floaty uphill paces and a jump that defined perfect. I used his photo in lectures on conformation. I studied his jump for research papers. Like Ross he was a little psychotic but when he trusted you he would overcome his own nature. Horses that can take on a 1.50m track are hard enough to find, here was a proper 1.60m horse and I loved his every quirk.

    Hobo got his name by being chucked off yard after yard for being dangerous, and he was, he had a tendency to panic with no self-preservation, and an exceptional talent for putting people in hospital, but this was never a horse who was nasty, just very afraid. 1.60m horses are not just bred, they are made. Everything must go well in training and then you still have to be lucky. Hobo was big, nervous and slow to mature. To go with his talent he needed big track rideability: my mantra became “for him I have time”. Eventually the offers started coming in and under pressure to sell I bought Sox the stallion to ease the transition. Still I could not bear to part with him and now I had two (albeit one who was intended for stud). Sox is a great horse, turns his hoof to anything, never lame, affiliated dressage and jumping, safe to hack and easy to handle. Next week I’ll go and collect a championship trophy from his only ever shot at showing. But Sox is not Hobo, Sox is a riding club horse and I never wanted to be a riding club rider. I’ve ridden Sox with a broken wrist, with one side limp, post-caesarian, and, I now know, with a wolf tooth fragment stuck in his jaw. He’s a grumpy old git, but I trust him with my kids and he’ll never hurt them. He doesn’t owe me anything yet the world will manage without his genes and he is now gelded.

    More pressure to sell came and went. I turned down big money offers for both horses, met a “them or me” ultimatum from the husband and he became an ex-husband. For years the divorce went on and the horses stood stabled, in divorce limbo, going round a horse-walker and losing health. By the time it was over Hobo never made it fully back into work. This year I retired him, which is an odd expression for a horse that hasn’t really started his career, but I can’t keep bringing him into work and watching him go lame, I have to let him go.

    Hobo is not dead. Every morning I lead him out of his stable he comes out in a big uphill march of a walk. I spent years on ground work with this horse, he leads beautifully, but most of all he moves beautifully. He has presence: he comes out of the stable roughed off and covered in mud and fur and I still think here is a horse. Here is what all horses should look like. I lead him up to the field and every time I watch his hooves – do they land heel first? Are they even? I fantasize that months of leading him up and down our stony path will harden his legs and he will come back, and I will feel that amazing jump, and the fences will be enormous and I will take photos to replace those lost to divorce, photos and memories which I can keep forever. Then we reach the field and I send him off and he hobbles, and I remember that I am an idiot, and I have to let him go.

    As a child at this time of year I read an issue of Horse and Hound where the equine stars of the day listed what they’d want for their dream Christmas, and adverts ran alongside. I don’t remember what most people wanted. I think Mary King wanted an equine swimming pool and a new set of jumps. When they came to Eddie Macken he only had one sentence: “I just want Boomerang back”. Suddenly I saw capitalism and advertorials through the eyes of this man who didn’t know what we’re talking about. His heart is broken and seemingly his career with it, and we understood, because we all wanted Boomerang back.

    I am very lucky and I know that. Pining over a (still-living) horse smacks of white, middle-class privilege, and hell yeah, comparatively I’m rich and thin. My Christmas list is ridiculously hopeful and contains saddles and bridles because I have four wonderful horses: Sox, Hobo, Denim (Hobo’s companion pony) and now the lovely Remus, a four year old. People are always asking how Remus is going, excited that for the first time in nearly a decade I’ve bought another horse. He’s going great I say, and he is. Better than I ever imagined, I say, because it’s true. Remus is exceptional, I hope one day he’ll be international. Maybe he’s even a 1.50m track horse and they’re hard to find. Certainly enough scope for me, don’t get the wrong idea – I’m no Olympic rider. What I can’t politely say is he’s not Hobo, he’s not even in Hobo’s league. He’s lovely, I’m fond of him, I’m impressed with him, but like people horses don’t replace each other. So Dear Santa, come on, this Christmas, even if only for one day, I just want my Hobo back.

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  • The tired horse-owners’ guide to not worrying in the winter

    Your horse shouldn’t be too hot or too cold, but that leaves a big range where temperature variation is fine. Yes, it’s colder at night. Your horse is not a soufflé.

    Your horse is not necessarily happier indoors. Rugs or shelters keep the wind/rain off, moving around & constant eating are great for generating heat and health, pig oil can help stave off the dreaded mud fever. Still not a soufflé.

    Sometimes it’s more convenient to keep your horse indoors. That’s OK too.

    Your horse is not wasted. Bored, maybe, unfit yes, tubby even, but he doesn’t dream of what might have been. He likes food and a bit of exercise, that’s about as far as his ambitions go.

    Your unlevel horse is not necessarily in pain. Your level horse is not necessarily sound. You’re his first line of defence – you notice change, you know what’s normal – good for you. Play safe when it comes to check ups, time off and vet calls, but no one ever fixed a horse by worrying.

    Your horse is not evil. He has a fairly weak grasp of good and bad, but he has completely nailed cause and effect. Your motivations are often a complete mystery to him, and he’s trying his best to get you trained. Don’t take it personally.

    Your horse may not need hard food. He might not need shoes. He might not need rugs. He might not need a full clip. You know best. Maybe you’re only motivated by budget or convenience – if well-being is not compromised then why not? It’s your leisure activity. No horse was ever embarrassed by his trace clip.

    Not all horses are the same. Just because it worked once/ for Ben Maher/ didn’t work for your last horse, doesn’t mean this horse isn’t going to make you look like an idiot by flying against all your previous experience. We’ve all been there, we’re only laughing cause this time it wasn’t us.

    Nothing is difficult because the steps are so small.

  • Checking for lameness with your iPhone

    My lovely and beautiful Hobo has been roughed off since March with subtle forelimb lameness. I thought I might as well use him to demonstrate gait analysis with a mobile phone (any phone will do, I happened to take this vid with an iPhone).

    First here’s the video at normal speed, taken at a funny angle during a poorly executed trot up. Obviously a side-on and front-on video of a horse trotting freely in a straight line on a loose rein, filmed in high speed and high resolution with a tripod is ideal. This video was taken with no real care or attention to show that it is not always necessary. I’ve included the video here so that you can familiarize yourself with the level of soundness – would you have spotted this horse as unsound?

    Once the video was recorded I could scan through it on my phone and choose the frames I wanted to look at. Here are some example frames for the near and off fore. If you are very unlucky your horse is lame on both sides. Let’s worry about that at the end. The majority of lameness’ happen in one leg so first let’s compare the same limb positions for both forelimbs and see if the horse is even on both sides.

    Some people get very excited about high speed video and seeing how the hoof lands, and that’s fair enough, because that really is exciting. Catching a proper hoof impact reliably and accurately takes a very high frame rate and well prepared ground so let’s not fool ourselves that we’re doing that. Instead let’s look at the forelimb just before it hits the ground, maximum extension if you will, but bearing in mind that we may not be catching exactly maximum. Here we don’t look at how forward the leg has swung, because that’s too unreliable (and we’re not trying to sell anything). Let’s just look at where the other foreleg is.

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    When the off fore (nearest you) is swinging through and near full extension the near fore is also swinging and flexed, when the near fore is swinging through, the off fore is still very much on the ground. So with our naff video, we’ve already spotted the asymmetry.We can check a few different strides to see if it’s a consistent thing, and it is.

    So what’s going on? Essentially he’s keeping one leg on the ground for longer – so he’s trying to take more of his weight with this leg. This is the most common indicator of lameness. He’s basically saving the leg he doesn’t want to use (the near fore), and trying to hop along on the other leg. There are plenty of others indicators in this horse, and these more specific ones tell us why he’s sparing that leg, but that’s probably enough to start with!

    If the horse was equally lame on both sides we’d actually need to compare this horse with himself (a previous video) or know enough to spot that this crouch gait was happening on both sides. If you look at the last frame you might instinctively already see that this Groucho Marx trot is not normal. You see the same gait in elephants (they don’t like to spring their full weight onto their legs either) and it’s not technically a run. So many future blog posts yet to write…

  • Five Steps to Straightness

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    Do you collapse on one side? Perhaps your shoulders look unlevel and try as you can you can’t seem to correct it. Maybe one heel doesn’t stay down, or your horse is just stiff and resistant on one side and you haven’t gotten around to blaming yourself yet. As you can see above I sit asymmetrically like the barber who never gets his own hair cut so I thought it’s about time I corrected my own biomechanics. You’re welcome to watch & comment and hopefully we’ll all learn something.

    Here are two pictures from a couple of weeks ago showing the side of shame at its worst. My left hip is too far advanced and as a result my leg is crunched up, little man has too much bend in the neck and his left shoulder has drifted out. Note also the crinkled numnah as I’m twisting it with my crooked riding of shame!

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    So: Step 1) Hips. I look like I have slightly asymmetrical shoulders. Technically I do but what’s more important and normally entirely overlooked is that I have very asymmetric hips. What you’re seeing in my shoulders is a result of that pelvis rotation, not a cause in itself. Similarly it looks like I’m sitting to the right, but this is just because I’m rotated to the right. If I pull my left hip back so that my pelvis is actually straight my horse stops resisting on the left. I can tell when I forget, because luckily my main horse is an unforgiving git – or if you prefer an excellent teaching horse who is sensitive to my aids. If I sort out my pelvis, my shoulders should look after themselves. Same goes for you, rubbish left leg.

    Step 2) Sleeping position. Have you ever noticed that people that crunch forward when they ride also sleep in the foetal position? I like to sleep on my right side, with my right leg straight, left leg bent up. It’s lovely, we snuggle. It’s allowing me to practice my folding up on the left bad habit to the extent that it feels natural & safe to sit that way. So I’m now going to stop reinforcing this asymmetry every minute of the day. I’ll try to sleep in a better position – stretching my left side; try not to sit on the sofa with my legs tucked up to the left; try not to carry my bag on my right shoulder… Basically if something feels natural I’m going to reverse it!

    Step 3) Halt. Not the horse, little horse recently has stopping as a forte – I need to practise my own halt. This morning I looked at my shoulders in the mirror, and noticed that when I’m on the ground they are indeed unlevel. Then I looked down and saw that my hands are uneven – I can see more of my left hand – so I tried to roll my left shoulder back. Then it twigged and I looked even further down. I’ve only got two legs and still I had not pulled off the square halt. My left foot was way in front. If I shut my eyes and stop left foot first it looks fine. Right foot first and I don’t naturally halt square. I’m not mentioning any names, but one of us is going to practise until I do.

    Step 4) Horse is going to go straight. Little boy and I had a good deal going – he likes to go crooked – I like to be crooked in a matching way! Great! He likes to put my weight on his right, where we both reinforce each other’s bad habits and just hope we never need to go left. So now that there’s a new regime in town we are going to go straight. Even when on a circle or going sideways we are going to be straight. My hip will be back, my weight will be down his left side as well, and I’ll know when it is as our lateral right will be as easy and round as our lateral work left, and when we land from a fence, we’ll go straight between two ground poles. For our piece de resistance when we turn left towards a jump or in counter canter in a test, he is not going to get gobby and complain. And I will pat him; with my right hand.

    Step 5) Biomechanics. I often video and check what’s going on. I video my riding & I video trot ups. Sometimes I’ll calculate joint angles, but this isn’t biomechanics. Joint angles and videos are kinematics and they’re useful – particularly if you have a robust way of calculating accurate and repeatable angles and aren’t just “joining the dots”. Biomechanics is the combination of these kinematics with kinetics – the study of the forces. By including the forces we can work out where the rotation originates – what is a primary problem and what is a secondary compensation, which muscle is too short, which one is too weak. Clinically and in training it’s important to consider the biomechanics, not just the kinematics. In my case that’s correct the pelvis, not the shoulder or leg position. If I just force my leg into the right place without correcting the pelvis I’ll make things worse. I need to correct the muscle imbalance & tightness that causes the pelvic rotation in the first place. That’s why I’m also working at it on the ground. So: I’m not going to force my left heel down, I’m going to drop my weight. I’m not going to correct my shoulders I’m going to straighten my spine. I’ll get my thumbs on top by correcting my elbows. I’ll go to the gym and stretch and correct until I’m neutral. I’m relying on you guys to keep me on the straight and narrow!

    Comments?

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  • Project for Performance Genetics LLC, USA, assessment of up to 300 young racehorses galloping past one after another, with instant analysis from a single pass each time, using our most robust marker-free gait analysis system yet.

    (Source: https://www.youtube.com/)

  • DIY Gait Analysis Software release

    As you may have already heard, I’m pleased to tell you that we more than made our target of 200 interested people and the software is definitely being released. I’m doing a staged release in order to have something out ASAP and avoiding having the whole thing stuck at 95% ready and not getting out there because of my need to feed my family and other animals!

    I’m hoping to get stage one (Beta version) out by the end of January. This is likely to include the basics, it may not have the rider analysis in it yet, and may not have the more robust features such as correcting for camera movement or look the most beautiful. There may be terms and conditions so that I’m not responsible if you drop a video camera on your foot, feel that your spouse in now neglected etc.

    Next release should be in March, and this will include a more polished, user-friendly interface, and whatever changes people have requested that I’ve been able to accommodate.

    Specialist releases and updates after that, including an option for the para riders to include limb absence where relevant, and one for cerebral palsy to include bone deformations. Neurological disorders should be covered by the existing releases. Similarly I’ll include some flexibility on the horse side for surgical shoes, tendon lesions etc. with the usual provisos that this is for monitoring your horses, it is not a diagnostic tool. You are, of course, welcome to use results as a part of an investigation, and to show them to clinicians.

    I’m keeping Twitter and FB updated for those that read those (http://www.facebook.com/EquineMechanics and https://twitter.com/@equinemechanics) and there’s more info on here under the #freesoftwareproject tag: https://equinemechanics.com/tagged/freesoftwareproject

  • Why the work you’re expecting is late…

  • Gait analysis, that uses markers, right?

    King Arthur, 2004

    Looking for the updated Free Gait Analysis Software post? Scroll down or click here

    Attaching markers is a clever idea that started when we (the biomechanists) wanted to assess human gait but videos were too big for available computer power. We needed to track how people moved, so we put retro-reflective markers on people and tracked the markers using infra-red cameras. Now we only had to deal with a set of point co-ordinates, not big bulky videos, and the computers could cope. Tracking more than seven co-ordinates was a major technical challenge so we placed the markers directly over the joints of interest and kept the number of markers low. 

    Move forward twenty years and computers can cope, cameras can cope, and we have fire-wire cables. Not only can we use video but we can use high-speed and multi-camera video set ups. I used to use spherical (not flat) markers and opto-electronic cameras for a lot of film industry applications because we need data that’s fast and easy, backwards compatible and not hugely accurate. The picture above is from the set of King Arthur in 2004, and clearly I was still using markers then, but I use this pic a lot to remind me what a nightmare the markers were on that shoot! These days I’d rarely attach markers for film, research or investigation.

    How can you track without markers?

    Tracking without markers is a lot more accurate, as your video contains an image of the horse, not just a point. If you only track a marker that is attached to the skin of the horse, then you’re reliant on how accurately it’s placed, and you have to cope with the fact that it moves will respect to the horse’s skeleton due to skin and muscle movement. However accurately you think you can place a marker, you can’t put it over the joint’s centre of rotation, as this is a functional, changing point not a fixed physical part of the joint. The very basic models place markers over the “joint centres” and just join the dots so their outputs should be taken with a pinch of salt. Moving one marker by a single centimetre results in a massive change in joint angles, even before skin movement comes in. I don’t think anyone has used these for clinical human assessments for over a decade!

    To track without markers the computational model simply fits a skeleton to the horse in the video, and works out functionally where the bones, joint centres, muscles and tendons must be. This is easy to do as we know that the bones don’t change length, that joints don’t dislocate and that skeleton moves in a predictable way. Combine these things and you get a system which can work out where a horse’s skeleton is accurately and reliably. If you are interested in the even more technical side you can have a browse through the publication list, and see joint angle accuracy of less than one degree, and even single millimetre accuracy on the joint centres in the really flash version! 

  • Free DIY Equine Gait Analysis Software – Updated!

    For quite a while I’ve had great intentions of releasing some free tools for riders to use at home, but never quite got around to it. As people may have heard (see Nov 1st Horse and Hound) I believe that in order to do full biomechanics you need a serious amount of training. However in terms of running a program and reading out results such as fetlock and hock motion, stride length, symmetry, and rider analysis (is the rider straight, if not how are they crooked), that’s the sort of thing I think riders should be able to do themselves for free and I’d be happy to hand out the software for people to do it. You don’t need any grasp of maths, just a video. The program will tell you there’s more motion in one joint than normal, or less use of one leg than another in a straight-forward, easy-to-understand way.

    Provisos:

    Not a diagnostic tool. Program can be used for monitoring and alerting to changes but if you are concerned about any results then contact your vet. Tendon and ligament strain calculations will not be included.

    Program will not tell you why a rider is crooked (just how they are) or what needs to change. Analysis at the muscular or intra-joint force level and predicting the effect of changes is where you need a clinically trained biomechanist, and some serious computational power. However you are free to attempt to correct asymmetries identified and rerun your program to see if you are improving. Similarly comparing footage at start and end of lessons or at home and in competition can be helpful and very encouraging.

    You can have the software for free, you can install it, run it as many times as you like, use it as much or as little as you want, and give it to your friends, but if lots of people ask me for help with interpreting results or to include new features I may charge for my time to do this.

    You have to take your own video. It doesn’t need to be great resolution or high-speed (although obviously this helps). You don’t need to attach markers. I use marker-free tracking which avoids all the obvious inaccuracies with attaching a marker to the skin. This means that you literally just need a video and your results will be a lot more accurate than if you used markers, because the positions of the joints are calculated not implied from a marker which may not be applied directly over the point it is meant to represent and in any case moves with the skin and other tissues.

    Final proviso, as I said at the beginning I have been meaning to do this for a while (actually about ten years) and I just never get around to it. I want to do it but giving stuff away for free involves protecting code, making nice interfaces, uploading space etc. and so is never quite the crocodile nearest the boat in my to do list. As a result I’m asking people to let me know if they’d be interested. If over 200 people email me (sian@equinemechanics.com) to say that you’re interested I promise to actually release the software, and send it to you first. If people would like to donate £1 or $1 towards the time taken, my Patreon account would love you for it, but donations are not compulsory.

    UPDATE: We now have more than our 200 supporters. Many thanks to everyone, sending an email may seem simple, but it has utterly convinced me that this is worth doing. Also many thanks to those who explained their stories and why it would particularly help them. Please do still email if you haven’t registered and would like to be kept informed, but the count is now shut. As everyone who emailed will know I did have to add one more proviso, which was that it is a non-commercial license. You can use it for anything, for yourself or your clients, but you can’t profit from it directly without buying a commercial license. If you and/or your horse are broken, things are tough enough, and there are plenty of services that you’ll have to pay for. Let’s not add anything to that.

    You can see all posts related to the Free Software Project here.

Equine Mechanics

Insights and resources on equine biomechanics for horse owners, trainers, and enthusiasts.