Fig. 2. (A) Representative patterns of normalized triceps muscle length (solid line) and elbow kinematics (dashed line) from one horse at 3.25 m s^-1. (Bi,ii) Representative patterns of normalized vastus muscle length and knee kinematics from two different horses at 3.25 m s^-1 showing the two different strain patterns. Joint flexion is reflected in a decreasing angle. The dotted vertical lines, corresponding to inflections in the kinematics curve, show how the strain patterns were divided into phases. The numbers correspond to the phases described in the text. The vastus pattern (Bii), seen in two horses, lacked phase 2, seen in one horse at all speeds and in a second horse at low speeds. This phase is shown in Bi. Mean duration of EMG activity is indicated by horizontal, black bars.