Adaptations in equine appendicular muscle activity and movement occur during induced fore- and hindlimb lameness: An electromyographic and kinematic evaluation.
Authors: St George Lindsay B, Spoormakers Tijn J P, Smit Ineke H, Hobbs Sarah Jane, Clayton Hilary M, Roy Serge H, van Weeren Paul René, Richards Jim, Serra Bragança Filipe M
Journal: Frontiers in veterinary science
Summary
# Editorial Summary Lameness prompts readily observable compensatory movement patterns, yet the underlying neuromuscular adaptations remain largely opaque to clinical examination. St George Lindsay and colleagues employed simultaneous three-dimensional kinematics and bilateral surface electromyography to quantify muscle activity and joint motion in eight horses during experimentally induced forelimb and hindlimb lameness (2–3/5 AAEP grade), comparing responses across triceps brachii, latissimus dorsi, superficial gluteal, biceps femoris and semitendinosus muscles. Beyond lameness-specific asymmetry indices, the researchers identified consistent increases in muscle activation amplitude (measured as average rectified value) across most muscles during both fore- and hindlimb lameness, with the notable exception of non-lame forelimb muscles, which paradoxically showed reduced activity during induced forelimb lameness—a finding that reflects the unloading strategy of the contralateral limb. Critically, electromyographic changes were tightly coupled to phasic shifts in the limb cycle and alterations in joint angles, demonstrating that compensatory muscle recruitment patterns are not merely increased effort, but rather coordinated neuromuscular reorganisation. These findings suggest that surface electromyography could develop into an objective diagnostic tool for quantifying subclinical adaptations to lameness that escape visual appraisal, potentially enabling earlier intervention and more nuanced assessment of rehabilitation efficacy during recovery.
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Practical Takeaways
- •Surface EMG can objectively quantify muscle compensation patterns during lameness that you cannot see by eye, potentially improving diagnostic accuracy beyond traditional visual assessment
- •Expect bilateral muscle recruitment changes even on the non-lame side during lameness—compensatory patterns are widespread, not just local to the affected limb
- •This technology may eventually help distinguish subtle neuromuscular changes in early or mild lameness cases that escape conventional lameness examinations
Key Findings
- •Muscle activation (ARV) increased across most muscles during induced forelimb and hindlimb lameness, except non-lame side forelimb muscles which decreased during forelimb lameness
- •Significant limb-specific changes in electromyographic activation timing and joint angles occurred during lameness, reflecting compensatory movement patterns to reduce weightbearing on lame limbs
- •Surface electromyography detected neuromuscular adaptations to lameness that are undetectable through visual observation alone
- •Bilateral muscular compensations and phasic activation shifts were consistent features across induced forelimb and hindlimb lameness conditions