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Keywords:

  • horse;
  • racehorse;
  • training;
  • body composition;
  • fat-free mass;
  • performance

Summary

Reasons for performing study

Few noninvasive measures associated with performance assessment are available for racehorse trainers. Evaluation of body composition of superior human sprinters has revealed a lower fat mass (FM), percentage (%) fat and greater fat-free mass (FFM), but to date there have been few studies evaluating this in racehorses.

Objectives

To determine the effects of age, gender and training on body composition and the relationship between body composition, physiological measurements and performance in Thoroughbred racehorses.

Methods

At 2, 5 and 8 months of training, rump fat thickness (RFT) was ultrasonographically measured in 1-, 2- and 3-year-old Thoroughbreds (n = 148), with FM, % fat and FFM calculated. Speed, heart rate, plasma lactate and serum creatine kinase concentrations were recorded during each fast work session. Training duration (number of training days) and intensity (number of fast work sessions) were collated for each training period. Retrospective racing performance was used to categorise horses as elite or nonelite.

Results

FFM was greater in males (P = 0.006) at all training stages. There were no interactions between training duration, intensity, gender and age (P>0.05); all effects were linear. Training duration had a negative effect on RFT (P = 0.0002), FM (P<0.0001) and % fat (P<0.0001) and a positive effect on FFM (P = 0.01). Training intensity had a negative effect on RFT (P = 0.009), FM (P<0.0001), % fat (P<0.0001) and FFM (P<0.0001). FFM was greater for elite vs. nonelite horses at all training stages (P = 0.003), for males (P = 0.05) and females (P = 0.04) and for 2- (P = 0.002) and 3-year-olds (P = 0.02).

Conclusions

While age and training affect body composition, FFM is associated with performance.

Potential relevance

Body composition assessment may assist fitness and performance evaluation.