Joint moments and power in equine gait: a preliminary study

A method is described for the estimation of joint moments of force and power in the equine forelimb using S-VHS video and force platform data. Video and force data were collected for 5 walking trials in a sound Dutch Warmblood horse. The sagittal plane positional and angular data were combined with the vertical and cranio-caudal ground reaction forces to calculate net joint moments of force in the sagittal plane across the carpal, fetlock and coffin joints during the stance phase of the forelimb. The mechanical power was calculated as the product of the netjoint moment and the joint's angular velocity. The carpus demonstrated oscillating periods of energy generation and absorption in early stance against a flexor moment, then an absorption phase at the end of stance as the carpus flexed against an extensor moment. The fetlock absorbed energy in early stance as it flexed against an extensor moment, then showed short periods of positive and negative work in mid-stance. Energy was generated across the fetlock as it extended for push-off. An extensor moment was measured at the coffin joint through most of stance, and this coincided with a phase of energy absorption followed by a longer phase of generation. In terminal stance, a flexor moment was produced and this was accompanied by a period of generation for push-off.