Sprinter, Miler or Stayer: are thoroughbred racehorses born that way?

What is it about?

Racehorses competing in short (i.e. ‘sprinters’), middle- or longer-distance (i.e. ‘stayers’) flat races are assumed to have natural variation in stride length. Sprinters have a short stride, Stayers have a long stride. No study has actually tested whether they are born this way, nor whether stride length associates with race outcomes. We used an exercise tracking system (the ‘Equimetre’™) to monitor racehorse stride parameters (peak length and frequency) at exercise intensities up to race-speed to assess how variable locomotory parameters were between category of racehorse (e.g. sprinter, miler, stayer). Pedigree information for all racehorses up to three-generations (1741 individuals: 633 unique, 261 founder sires; 1634 unique, 699 founder dams) was incorporated. We found that during training, ‘sprinters’ had a shorter stride of higher frequency than stayers (P<.001) and covered consecutive 200m segments faster than stayers (P<.001). Within each category of racehorse, relatively shorter or longer stride conferred no greater chance of winning a race. The odds of winning were higher for colts than for fillies or geldings (P<.001) but decreased as the race class increased (up to Group 1). Peak stride length and frequency were moderately heritable (h2 = 0.15 and 0.20, respectively).

Featured Image

Photo by Lumin Osity on Unsplash

Photo by Lumin Osity on Unsplash

Why is it important?

Differences in locomotory characteristics are apparent between sprinters and stayers (e.g., shorter peak stride in sprinters) during routine training, even after accounting for their pedigree information. Both peak stride length and frequency were moderately heritable, but within race distance categories, were not significantly associated with race success.

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