M. L. PETERSON*, R. F. REISER II † , P.-H. KUO, D. W. RADFORD ‡ and C. W. Mc Ilwraith § Equine Veterinary Journal May 2010 42 4 351 - 357 Reasons for performing study: Differences in racing times have been noted on synthetic track surfaces that appear to depend on the temperature of the track. No published study to date has considered this effect in a systematic manner. Objectives: To investigate the relationship between temperature of track and speed of horses racing on a synthetic surface. Potential changes in the wax component of the synthetic track were investigated as one possible cause of changes in the track speed at the temperatures observed. Methods: At Del Mar racetrack (California, USA), the air, surface and subsurface temperatures at 4 depths in the synthetic race surface were measured periodically throughout the day over a 42 day period. The 6 furlong (1.2 km) race (afternoon) and fast training 'work' (morning) times were also compiled. Samples of the track were obtained and the wax separated using a solvent separation technique. Differential scanning calorimetry was used to determine the range of temperatures at which the wax from the track underwent softening and other material changes. Transformation temperatures were compared to temperatures acquired from the track to evaluate the likelihood of changes in the wax properties during racing. Results: Average air, surface and subsurface temperatures changed significantly throughout the day. Temperatures were higher during the afternoon race sessions and race times were significantly slower compared to morning work times. Temperatures at which some of the components of the wax began to soften were found to be within the range of temperature measured during track operation. Conclusions: A correlation was found between temperature of the synthetic track and speed of horse. Wax separated from the track showed that the temperatures experienced in the surface during normal operation exceed the temperatures at which the wax begins to experience thermal transformation. It is therefore hypothesised that the wax may be a cause of the observed changes in the track performance. Potential relevance: Future work should include a study of components of the synthetic track responsible for the change and epidemiological association of risk of injury.

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