Effect of speed and leading or trailing limbs on surface muscle activities during canter in Thoroughbred horses.
Authors: Takahashi Yuji, Takahashi Toshiyuki, Mukai Kazutaka, Ebisuda Yusaku, Ohmura Hajime
Journal: PloS one
Summary
# Editorial Summary Canter is a fundamentally asymmetrical gait, yet most research on equine muscle physiology focuses on symmetrical movements; Takahashi and colleagues addressed this gap by investigating how both speed and lead-side (whether a limb is leading or trailing) influence muscle activation patterns in Thoroughbreds during cantering. Using surface electromyography (sEMG) on seven horses, they recorded activity from six muscles across the forelimb (brachiocephalicus, infraspinatus, triceps brachii) and hindlimb (gluteus medius, semitendinosus, flexor digitorum longus) whilst animals cantered at speeds of 7, 10 and 13 m/s on both left and right leads without changing lead. As expected, increased speed elevated muscle activation across all muscles (15–134% increase from 7 to 13 m/s), with stride duration and duty factors decreasing consistently; however, the lead-side effect proved more nuanced, with forelimb muscles (particularly brachiocephalicus and infraspinatus) working significantly harder on the leading side (+19–47%), whilst hindlimb muscles (gluteus medius and semitendinosus) paradoxically showed greater activation on the trailing side (+19–20%). These findings challenge the assumption that muscle behaviour during canter is uniform across both sides, suggesting that practitioners designing training or rehabilitation programmes for canter and gallop work should account for asymmetrical loading patterns—particularly when addressing one-sidedness or managing muscular imbalances in performance horses.
Read the full abstract on PubMed
Practical Takeaways
- •Consider both canter speed and lead side when designing training or rehabilitation programs, as different muscle groups respond differently to these variables
- •Trailing limbs are activated earlier in the stride cycle and show different loading patterns than leading limbs—this asymmetry should be factored into conditioning work
- •Higher speeds increase muscle demands substantially (up to 2.3× at top speed); adjust training intensity accordingly and monitor for asymmetric fatigue
Key Findings
- •Integrated EMG increased 15-134% from 7 m/s to 13 m/s across all muscles studied
- •Brachiocephalicus and infraspinatus showed greater activity in leading limbs (+47% and +19% respectively), while gluteus medius and semitendinosus showed greater activity in trailing limbs (+20% and +19%)
- •Muscle onset timing was significantly earlier in trailing limbs for triceps brachii, gluteus medius, and semitendinosus compared to leading limbs
- •Speed significantly reduced stride duration and duty factors regardless of lead side