Effect of fatigue on equine metacarpophalangeal joint kinematics – a single horse pilot study

Abstract The objective was to validate a scientific method for characterizing equine metacarpophalangeal joint (MCPJ) motion in the non-fatigued and fatigued states using a single horse at trot, slow canter, and fast canter. One healthy Thoroughbred gelding exercised on a treadmill to exhaustion [fatigued state] (heart rate >190 BPM and blood lactate >10 mmol/L) while bilateral MCPJ angular data were acquired using electrogoniometry. Blood lactate and heart rate reflected transition from non-fatigued to fatigued states with increasing exercise duration and treadmill speed. Electrogoniometry consistently demonstrated: increase in mean MCPJ maximum extension angle with onset of fatigue; altered extension and flexion angular velocities with onset of fatigue; and increasing stride duration and decreasing stride frequency with onset of fatigue. The method allowed a preliminary but comprehensive characterization of the dynamic relationship between MCPJ kinematics and fatigue, prompting the need for multi-subject studies that may enhance our ability to moderate exercise-related distal limb injury in equine athletes.