Fig. 1. Representative data for accelerometer and EMG of a forelimb (A) and hind limb (B) of a horse trotting on a level treadmill at 3.5 m s^-1. The graphs show the accelerometer used to identify stance phase, starting with hoof contact (axis origin) and lift off (denoted by the broken line). Stance is indicated by the solid bar at the bottom. EMG activity patterns, below the accelerometer record, show that both muscles are active early in stance.