Reliability of surface electromyographic (sEMG) measures of equine axial and appendicular muscles during overground trot.
Authors: St George L, Spoormakers T J P, Roy S H, Hobbs S J, Clayton H M, Richards J, Serra Bragança F M
Journal: PloS one
Summary
Surface electromyography (sEMG) offers considerable promise for objective assessment of muscle activity during equine gait analysis, but its reliability as a clinical tool had never been formally demonstrated until this investigation. St George and colleagues recorded bilateral sEMG from six key muscles (triceps brachii, latissimus dorsi, longissimus dorsi, biceps femoris, superficial gluteal, and semitendinosus) in eight sound horses during in-hand trot across two sessions separated by at least 24 hours, processing ten trot strides per session using standardised signal conditioning and normalisation protocols. Most muscles demonstrated excellent between-session reliability (coefficient of multiple correlation >0.90), particularly the bilateral gluteal, semitendinosus, triceps, and longissimus, with latissimus and left biceps showing good reliability (>0.75); however, muscle activation patterns varied considerably between individual horses, limiting direct cross-subject comparison. Within-session profiles for individual horses proved highly reliable, establishing sEMG as a valid tool for longitudinal monitoring of intra-individual muscle activity changes during rehabilitation or performance optimisation. For practitioners seeking objective gait data, sEMG can dependably track whether a specific horse's muscle recruitment patterns are normalising or deteriorating, though clinicians should avoid using sEMG reference values derived from other horses as direct comparatives.
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Practical Takeaways
- •sEMG is a valid tool for tracking muscle activity changes within individual horses over time (e.g. rehabilitation progression), but baseline data must be established per horse
- •Do not use sEMG data to directly compare muscle function between different horses without establishing individual baselines first
- •In-hand trot sEMG assessment of core and limb muscles is reproducible enough for clinical monitoring of rehabilitation or performance changes in individual cases
Key Findings
- •Intra-horse sEMG profiles showed excellent within-session and between-session reliability (CMC >0.90) for gluteal, semitendinosus, triceps, and longissimus muscles
- •Inter-subject (between-horse) sEMG profiles were significantly more variable than intra-subject profiles, limiting direct cross-horse comparisons
- •sEMG can reliably monitor individual horse muscle activity patterns across multiple sessions at in-hand trot, despite between-session variability
- •Bilateral latissimus and left biceps showed good (not excellent) between-session reliability with CMC 0.78-0.88