Racetrack layouts are conventionally based on two straight lines connected by two circular curves. In the curves, the horse is subject to centrifugal force which tends to pull the horse out of the curve. The centrifugal force increases as the radius of the curve decreases or the speed increases. To compensate for the effect of this force, curves are mainly drawn with an increasing cant from the inside of the rail to the outside. This type of design can also be seen in curves of motorways or railways. When there is no curve canting, the horse is forced to reduce its speed and compensate by adapting its locomotion to stay on the inside of the curve and not give in to the centrifugal force. This compensation can induce a higher load on the joints. It has been shown that a poorly designed runway can lead to asymmetric locomotion, resulting in locomotor disturbances and injuries. Furthermore, it is also necessary to define the slow transition between the curve and the straight line, this will favor the horse’s balance and natural stride and thus limit the mechanical stress on the limbs. It is therefore important to have a well-designed track to boost the horse’s speed and natural stride.
Straight line training should be preferred to limit mechanical pressures. However, training in bends should not be neglected in order to accustom the horse to the sensations and thus improve the proprioception in the bends. It is also important to train on left-handed or right-handed tracks to avoid creating muscular asymmetry and compensatory phenomena of locomotion linked to training in only one direction of rotation. As all horses have their preferred side, it is interesting to draw objective figures from the right-handed and left-handed trainings. In order to make informed racing choices, knowing the time variations over a given interval, on a left-handed track versus a right-handed track, can be decisive.
In order to evaluate the influence of the curve on race times, we can compare the 1600m races at Deauville in a straight line and in curves, for races with conditions and handicap races, on grass.
Comparison of average times and speeds for a straight race and a race on a right-handed track over 1600m, on grass, at the Deauville racecourse for a race with conditions and a handicap race.
Non-straight races are on average 11% slower than straight races. It’s on the first 1200m that the difference is the biggest, indeed it is where the turn happens. The speeds over the last 400m are almost identical. We notice a slightly lower speed of 2 km/h on the last 200m of the right-handed race. This can possibly be explained by the fact that despite the lower speed, racing with bends requires more energy to compensate for the effects of centrifugal force, energy that is no longer available to maintain the effort to the finish line. However, this hypothesis still has to be confirmed.
Every race track has specificities. Therefore, it’s important to train horses in order for them to be fully performant facing all kind of tracks, despite their design specificities.
Keywords: track design, racing speed, centrifugal force, locomotion