Association Between Stride Parameters and Racetrack Curvature for Thoroughbred Chuckwagon Horses.

Overview

• This study examined how the curvature of racetracks affects stride parameters—specifically stride length and stride frequency—in Thoroughbred Chuckwagon horses during training.
• The research found that racetrack curvature influences horses’ speed and stride characteristics, factors previously linked to injury risks in racehorses.

Background and Rationale

• Musculoskeletal injuries are a common concern in galloping racehorses and are linked to changes in stride length and speed observed over consecutive races.
• Previous research has shown that a decrease in stride length and speed can signal increased injury risk.
• Racetrack curvature is known to affect horses’ maximal running speed, but its effect on stride parameters such as stride length (SL) and stride frequency (SF) had not been comprehensively studied.
• The hypothesis was that racetrack curvature influences stride parameters, potentially impacting injury risk.

Methods

• Subjects: 28 Thoroughbred Chuckwagon horses used in training sessions.
• Data Collection: Global Navigation Satellite System (GNSS) loggers were attached to the horses to measure:
  • Speed
  • Stride Length (SL)
  • Stride Frequency (SF)
• Data was segmented into consecutive 100-meter sections to calculate average speed, SL, and SF for each segment.
• Statistical Analysis:
  • Linear mixed models examined the influence of racetrack curvature on speed (speed as the dependent variable, curvature as fixed factor, horse as random factor).
  • Another set of mixed models studied the effects of curvature and speed on stride parameters (SL and SF as outputs), considering interaction terms between curvature and speed, with horse as a random factor.

Key Findings

• Speed: Curvature was significantly associated with an increase in speed (p = 0.004).
  • At a curvature of 60° per 100 m, horses increased their speed by 0.264 m/s compared to running on a straight track segment.
  • This speed increase might be influenced by fatigue confounding (e.g., horses might slow down on straights due to tiredness).
• Stride Length (SL): Curvature caused a significant decrease in stride length (p < 0.001).
  • At the median speed of 14.5 m/s and 60° curvature, there was a 0.137 m (2.1%) reduction in stride length compared to straight sections.
• Stride Frequency (SF): Curvature caused a significant increase in stride frequency (p < 0.001).
  • At 14.5 m/s and 60° curvature, stride frequency increased by 0.053 Hz (2.4%) relative to straight track segments.
• Importantly, the magnitude of the effects of curvature on SL and SF depended on speed (interaction p < 0.001).

Interpretation and Implications

• Changes in stride parameters caused by racetrack curvature (decreased stride length and increased stride frequency) are similar in magnitude to changes previously linked to increased injury risk during consecutive races.
• This suggests that the natural changes in stride caused by curved sections of a racetrack might interact with or contribute to injury risk in Thoroughbred Chuckwagon horses.
• The findings highlight the importance of considering racetrack geometry in managing horse performance and injury prevention strategies.
• Since speed was also influenced by curvature and fatigue might confound some observations, more work may be required to disentangle these effects, particularly during actual races rather than training.

Conclusions

• There is a significant association between racetrack curvature and stride parameters in Thoroughbred Chuckwagon horses.
• Specifically, increased track curvature leads to higher speeds, shorter stride lengths, and higher stride frequencies.
• These alterations in stride parameters correspond to previously identified predictors of musculoskeletal injury risk in racehorses.
• Thus, racetrack curvature should be taken into account when assessing injury risk and training regimens for chuckwagon racehorses.