http://www.signonsandiego.com/sports/delmarraces//20050907-9999-lz1c07turf.htmlHow veterinary science, synthetic soils and robotics are changing thoroughbred racing
By Suzanne Clancy
UNION-TRIBUNE
September 7, 2005
The scents of kettle corn and fine perfume will mingle with those of dust, sweat and well-oiled leather as crowds fill the paddock this afternoon for the last day of racing at Old Del Mar. After the last horse crosses the wire, close to 3,000 horses will have roared down the backstretch this season, thrilling casual fans and railbird regulars alike. Each race offers a new opportunity for glory and excitement – and payouts at the betting window – but also risk of traumatic injury to horse and jockey.
Last month, the Del Mar Thoroughbred Club, long recognized as an innovator and leader in the racing industry, hosted a meeting of experts from around the U.S., Europe and Australia, who shared the latest science on racing surfaces and minimizing injuries.
\"Most sports – football, golf – have their turf down to an exact science,\" said Leif Dickinson, superintendent of Del Mar\'s turf course and organizer of the conference. \"We\'d like to see more standardization.\"
Demanding pursuit
As fans of Seabiscuit will recall, in its early days, thoroughbred racing was frequently a brutal business for both horse and jockey. Developments in emergency and veterinary medicine, not to mention institution of regulations and insurance policies, have changed the picture dramatically.
In California, every horse that is put down or dies of natural causes at a racetrack is subject to compulsory necropsy, a program headed by Susan M. Stover, a veterinary professor at UC Davis.
Efforts by Stover\'s team and others in the 1990s eliminated the use of \"toe grabs\" in the state. These metal cleats were attached to the front edges of horseshoes to increase speed and traction, but were shown to lead to higher incidences of suspensory ligament and other musculoskeletal injuries.
Despite the advances, racing remains a demanding profession for a horse. A hoof strikes the ground with 5,000 pounds of pressure on a bone the size of your wrist, according to Steve Wood, superintendent of Del Mar\'s dirt track.
In order to measure those pressures precisely, Michael \"Mick\" Peterson, an engineering professor at the University of Maine, has developed a robotic hoof tester. The device is designed to drop down to the ground at the same angle and velocity as the front hoof of a galloping horse. It measures what a living hoof experiences when it meets a particular racing surface.
\"We need to develop measures based, not on inputs like water or sand content, but on biomechanics,\" said Peterson.
Within each galloping stride, a racehorse\'s front hooves go through four distinct phases. The first is the impact phase, when a hoof initially strikes the surface. Then the horse\'s full weight is transferred to that hoof during the stance phase. This is followed by the propulsive phase, when the hoof \"breaks over\" and begins to push off into the airborne swing phase, in which the horse\'s weight is transferred to the next leg that contacts the ground.
During impact, a hoof experiences \"deceleration in a very big way, we\'re talking 80 to 100 Gs,\" according to Peterson, as it slows from approximately 70 mph to a momentary standstill to make full contact with the ground and bear the horse\'s weight. By comparison, fighter pilots typically experience forces of about 6 to 9 Gs.
As the hoof enters the propulsive phase, this deceleration reverses – the hoof must now accelerate to push off the ground and catch up with the forward motion of the horse\'s body mass.
By measuring load and acceleration in response to various surfaces, the robot has shown different track layers are important to different phases of the gait. The cushion, typically a three-inch layer of soft dirt, slows down entry and can reduce the load on a hoof by up to 50 percent. But it\'s the underlying areas that are important for supporting propulsion.
\"We saw that the horse can be affected by what\'s going on up to a foot below the surface,\" Peterson said.
The reversal of acceleration that occurs between stance and propulsion exerts a force called shear stress on the base layers underlying the cushion. If those layers cannot withstand this stress, shear failure occurs, and the hoof does not decelerate at an optimum rate.
\"Horsemen talk about a \'cuppy\' track,\" said Peterson, \"when the hooves slip and can\'t propel. We showed that what happens on that type of track is insufficient deceleration – it drops down to only 30 to 40 Gs.\"
The horse must work that much harder to push itself forward, which leads to enormous stresses on the forelimbs. Such forelimb injuries are the most commonly seen on racetracks.
If the base is infinitely stiff – \"if we use concrete,\" in Peterson\'s words, shear failure will not occur. \"But we can\'t do that because we have to worry about the load on the horse\'s legs. So we have contradictory demands on the surface, and we need to find a balance.\"
In order to examine track base layers, Peterson has paired his robot with ground-penetrating radar. He has traversed tracks around the U.S. with machines strapped to the back of a station wagon. At one track, the robot indicated an unusually soft area, and the radar revealed a base layer that was sinking away from the cushion.
During morning workouts at Del Mar last season, robot readings showed the track getting harder. As a result, Wood checked his equipment and found a dysfunctional harrow, the spike-toothed machine used to redistribute soil on the track. Workout times were also a bit fast, another clue that something was up.
\"Did we prevent an injury? We can\'t know that, but we do know we can be proactive, to act before injuries creep up or horsemen complain,\" said Peterson. Currently, his device is a prototype, but eventually robotic testers might be commercially produced and readily available to track managers.
Seeing into bones
Veterinarians, trainers and grooms also do all they can to head off injuries before they appear. After races and workouts, grooms on the backside rub down horses\' legs, probing for heat, swelling and anything that feels wrong. They apply ice, liniments, wraps and poultices, some from recipes that have been honed through decades of experimentation and are well-guarded family secrets.
Rick Arthur, an attending veterinarian at Del Mar, recalls trainers who insisted on mud gathered from a specific location in San Pablo Bay.
Advances in veterinary medicine, however, are making it possible to detect issues before they become apparent to even the most practiced hand and eye.
In the early 1990s, results from Stover\'s team showed that a new technique called nuclear scintigraphy could be used to detect bone remodeling in thoroughbreds before catastrophic injury. In nuclear imaging, radioisotopes are detected with a gamma camera. Areas that \"light up\" on a nuclear image indicate increased physiological activity. A screening facility, sponsored by the Dolly Green Foundation, was instituted at Santa Anita Park in Arcadia. Arthur has directed it since 1993.
In that time, more than 6,000 horses have been screened for bone changes that warn of impending fractures. Horses are referred for screening by their attending veterinarians.
\"Horses that would have broken down and been put down 10 years ago are now coming back to race, and they race very well,\" said Arthur. He recounted two cases of young horses that were diagnosed with stress-related remodeling in the tibia, the long bones of the upper leg. With proper rest, both horses recovered and went on to win Horse of the Year titles.
But ultimately, Arthur believes, more information is needed on how injuries, equine biomechanics and track surfaces correlate. For example, at the Newmarket (England) track, fractures of the pastern, the bone between the hoof and ankle, are commonly seen. At Del Mar, however, fractures in the cannon bone above the ankle predominate.
\"And we don\'t know why. We need a hoof\'s-eye view,\" Arthur said, which is why he and his colleagues are watching Peterson\'s work with great interest.
Leveling the field
Consistency of the track is paramount, according to Arthur. \"Ideally, all tracks would be the same, but variability within a track is a bigger problem (than variability between tracks). These horses are working at maximum physical ability – you don\'t want them to hit a hole.\"
In an effort to standardize conditions, some are seeking to eliminate traditional dirt tracks altogether and replace them with a synthetic dirt. Several manufacturers have developed so-called all-weather surfaces, consisting of a blend of sand and polymers of rubber or polypropylene doused with a wax coating.
The result is a granular substance that can be rolled out just like a traditional dirt track but is resistant to both rain and drying out.
One of these commercial blends, Polytrack, has been used in England since 1987 and was installed at Kentucky\'s Keeneland training track in 2004. The synthetic blend appears to cushion the impact better than natural surfaces. Horses that trained on Polytrack at Keeneland made 28 percent more starts than their peer group a year earlier, indicating a lower frequency of training injuries.
(The track reports it has not needed to water the surface since installation. By contrast, Del Mar typically uses 80,000 gallons of water a day.)
Synthetic surfaces offer an additional advantage in that turns can be banked, which makes them safer and more negotiable for horses. As they fly around turns, horses\' forelegs have to work against centrifugal forces that exert a lateral pull, stressing the joints. Banking reduces lateral forces on the joints by tilting the bones away from the vertical, directing stress to travel straight down through the bones rather than tugging on joints.
George Pratt, professor emeritus at the Massachusetts Institute of Technology, has developed formulas for banking turns based on the radius of the turn, the average weight of a racehorse and the angle at which horses lean into their turns. Using a standard physics equation for computing centrifugal forces, Pratt determined the lateral force on an average turn to be 240 pounds.
This force can be offset by banking. According to Pratt\'s formula, a 1,000 pound horse leaning into a turn at a typical four-degree angle will experience a lateral force reduction of 170 pounds on a turn banked 10 percent. A 2-percentbanked turn reduces lateral force by only 90 pounds.
Most tracks in the U.S. are banked only a few percent, because dirt simply won\'t remain in place if banked more steeply. Michael Dickinson, trainer at Tapeta Farm in Maryland, says he has successfully banked turns at 10 percent using a trademarked synthetic surface he developed.
This summer, Polytrack was laid down on the main track at Turfway Park in Kentucky. Racing on this surface will begin for the first time in the U.S. in September.
Although no one has yet created a synthetic turf suitable for racing, plastics are gaining a foothold. This season, Leif Dickinson is testing turf grids at Del Mar, polypropylene \"honeycombs\" that are inserted under the turf and help anchor roots into soil.
\"We want to eliminate large divots, chunks of turf coming up,\" he said. With the grids, \"we\'re seeing the horses lightly tamping down into the turf, which is what we want.\"
Dickinson and his colleagues believe that exchanging information is an important first step toward making race tracks safer for horses and jockeys. Participants repeatedly remarked, \"If this (advance) saves one horse, it\'s worth it.\" No doubt those clustered along the paddock rail anticipating post time will agree.
Find this article at:
http://signonsandiego.printthis.clickability.com/pt/cpt?action=cpt&title=SignOnSanDiego.c...
