Effects of Fatigue on Stride Parameters in Thoroughbred Racehorses During Races.
Authors: Takahashi Yuji, Takahashi Toshiyuki, Mukai Kazutaka, Ohmura Hajime
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Stride Adaptations Under Race Fatigue in Thoroughbreds Japanese researchers analysed how Thoroughbreds modify their locomotion as fatigue accumulates during 2400-m turf races, comparing stride mechanics between the opening and closing lap using high-speed video analysis positioned near the finishing post. Across multiple horses, the second lap revealed substantial reductions in speed (17.3 to 16.0 m/s), stride frequency (2.34 to 2.21 strides/s) and overall stride length (7.42 to 7.25 m), alongside significant alterations in individual limb placements—notably a shortened diagonal step and lengthened hind and airborne phases. When mathematically adjusting for the speed decrease itself, fatigue independently drove further increases in hind, fore and airborne step lengths whilst the diagonal step compressed, indicating horses adopted a more restricted body posture rather than maintaining their natural extended stride. These findings matter practically because they demonstrate that fatigued horses fundamentally alter their gait mechanics beyond simple speed reduction, potentially increasing injury risk through altered loading patterns and decreased shock absorption—information that should inform training load management, recovery protocols and post-race assessment strategies for equine practitioners monitoring musculoskeletal health in racing stock.
Read the full abstract on PubMed
Practical Takeaways
- •Fatigue-induced gait changes in racing Thoroughbreds include reduced stride frequency and altered step proportions; trainers and veterinarians should recognize these biomechanical shifts as indicators of fatigue accumulation during races
- •The compensatory lengthening of certain steps (hind, fore, airborne) despite overall reduced stride length suggests horses adopt a different locomotor strategy under fatigue that may have implications for injury risk and recovery protocols
- •Understanding that fatigued horses cannot fully extend their body may inform conditioning programs and race pacing strategies to minimize excessive fatigue-related biomechanical stress
Key Findings
- •Running speed decreased significantly from 17.3±1.3 m/s in lap 1 to 16.0±0.9 m/s in lap 2 (P<0.01)
- •Stride frequency decreased from 2.34±0.08 to 2.21±0.09 strides/s with fatigue (P<0.01)
- •When controlling for speed, fatigued horses showed decreased diagonal step length but increased hind step, fore step, airborne step, and stride length, suggesting altered gait mechanics under fatigue
- •Horses demonstrated reduced body extension capability when fatigued, with compensatory changes in individual limb step lengths