Conditions under foot | Trainer Magazine | European Trainer Article Index

Mar 28

Mar 28 Conditions under foot

FARRIER Mitch Taylor lugs a camera instead of a tool box today. Behind him along the rail at Keeneland’s training track trails a crew of technicians, a couple of horses, an exercise rider and an equine motion-analysis software developer. Their goal is not to shoe the horses, but to tape them as they run. But first they must convince the exercise rider that only the strides caught by the camera count, and that the horse needs to maintain the same speed, which is tracked by a police radar gun. Taylor will collect simple video footage that real people – trainers, owners, racetrack officials, veterinarians, farriers – can watch and understand. He will replay the tape over and over, until people see the difference between dirt and synthetic stride characteristics. That is, if there is one. Welcome to American horse racing. Since the public outcry over the tragic deaths of Eight Belles, George Washington, and other stakes horses on national television, racing is on the defensive, looking for answers. Like a fairgoer caught in a hall of mirrors, racing looks one way, then the next, and sees a distorted picture of itself, partly because the very things it once knew to be true may not be so anymore. When the US Jockey Club’s first Welfare and Safety Summit (WSS) tackled the isolated topic of the possible ill effects of toe-grabs, Taylor’s crew headed to the track to record the difference in foot action between different types of shoes. The WSS Shoeing and Hoof Care Committee built a case that brought about a swift model rule change adopted by several state jurisdictions to reduce the height of toe grabs to a miniscule 4 mm. Pandora’s Box creaked open. The entire 20th century was a grand era for horseracing, but a tough time for improvements to our base of knowledge about the horse. In the 1800s, the Science of Speed occupied the minds of men who tinkered with shoes, saddles, track designs, and whatever else they could think of as a variable. Their goal was a faster horse, a better horse. But it wasn’t until the late 1900s that the new science of biomechanics spilled over from human sports, bringing leading minds like Doug Leach, Hilary Clayton, George Pratt, and others to examine the motion of the horse and the role of the surface. For the most part, they were ignored. Their detailed PhDs, papers and reams of data met with murmurs of, “How interesting”, as horsemen went back to their daily routines, doing what had always worked for them, running horses on surfaces that suited them, at distances that suited them, over intervals that suited them. Now, 25 years later, the public, press and even the US Government are asking: Why did that horse take a bad step? “That’s racing” just wasn’t enough of an answer after a switch to the much-heralded safety option of an artificial track failed to reverse the breakdown trend. Fanned out across the globe is a growing cadre of researchers ready and willing to study the surface, the shoes, the shape of the hoof, the humidity in the air, the angle of the sun – whatever it takes to unlock some clues. So here comes Mitch Taylor with his entourage and his high-tech camera. He’s not going to explain much, he’s going to show you Stride length and stride frequency are the key factors in determining speed, but the New Reality puts more emphasis on shear force, friction and the horizontal movement of the foot after it touches the ground. The goal is an efficient stride, a safer step. According to mechanical engineer Mick Peterson of the University of Maine, the additional variables are 1) how quickly the foot stops when it hits, 2) how hard the landing is, and 3) how much resistance the ground provides for the hoof to push off against as weight passes over the hoof. The task of relative shock absorption is assigned to the fetlock; it flexes more or less according to the hardness of the track. A fetlock is under more stress on a hard surface, Peterson tells us. The more the fetlock flexes, the more return spring is released as the horse is propelled forward off that foot. Peterson applies the one-two punch to understanding stress on the foot. The hardness effect on the fetlock’s flexion on landing is the right jab; the shear strength of the track is the left hook. Shear strength, quite simply, determines the pressure that will be on the front of hoof when it impacts the track; that pressure will stop the hoof. The higher the shear force, the faster the stop. It will also assist (or handicap) the push-off factor. A track with low shear strength will allow the hoof to slide several inches before it stops. A track with high shear strength will snap it to a quicker halt. The sliding may be kinder to the landing, but it makes pushing off more difficult—there’s nothing to push off against. New, more sophisticated high-speed video can compare the relative horizontal motion of the hoof after it disappears into the surface. It was not until 1995 that Professor Willem Back at the University of Utrecht determined there was a measurable difference in the horizontal movement of the front and hind hooves on landing. The normal hind foot slides more than the normal front, Back showed. To understand what is really going on in the hoof, strain gauges and accelerometers are the new buzz words, but the true key may be in the study of the moving hoof through the use of finite element (FE) analysis, or a computerised simulation of running hoofs interacting with the ground. Leading researchers in this field include Jeff Thomason at the University of Guelph in Canada, Simon Collins at the Animal Health Trust in Newmarket, England, and Christine Hinterhofer at the University of Vienna in Austria. Thomason’s research focuses on the racehorse but all the research is applicable in describing the action of tendons and the effects of shear. According to landmark research conducted by Professor George Pratt at Massachusetts Institute of Technology in 1981, the horse does not pull itself forward as it gallops. The horse may be moving forward at 55 feet per second, but the hoof is moving downward at 20 feet per second, as well; the hoof is actually moving faster than the preached against toe grabs, calks, and stickers, which he felt would interrupt the foot’s ideal contact with and departure from the ground. “It is imperative that the hoof be allowed to slip forward”, Pratt wrote in 1981. But, he would have added, not forward too much. The intense light that the WSS rule shone on one shoeing modification opened Pandora’s Box, to be sure, but concurrent events showing that artificial surfaces were not a one-stop solution to end breakdowns helped temper the apprehension that banning toe grabs wasn’t enough—but what’s left? Peterson, Thomason, Back and their students are what’s left. They are still out there, measuring and recording how the horse’s foot is impacted by racetrack surfaces. “We need to measure what the horse feels”, says Peterson, who has become a de facto spokesman for the new spirit of proactive research and collaboration in racing science. “We (now) have synthetic surfaces…but we do not have engineered surfaces (yet)”, he warns. “We need to change some things.” Look closely and you’ll see the word “can” inside “change”. Speaking in Saratoga Springs in August 2008, Taylor noted, “High speed video indicates that, at midstance, feet do not penetrate into the cushion as much as on traditional dirt surfaces; therefore, one can assume that the toe is less able to penetrate the surface during the breakover phase and the limb has to rotate over the toe instead of the toe rotating into the surface as in dirt. The result of such an alteration would be that stabilising muscles are being asked to function as propulsion-generating muscles. This theory is strengthened by the observation that there is less kick back on SRS. “Because of the fibrous make-up and more resilient characteristics the foot would logically have a harder time breaking through the surface, unlike sand, which shears away easily.” horse’s body. Even 28 years ago, Pratt

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