Fig. 6. Muscle force, electromyographic (EMG) activity, fascicle length, and power output for the lateral gastrocnemius, LG, and peroneus longus, PL, muscles in two different turkeys running at a steady speed of 2 m s^–1 on a declined (–12°), level, and inclined (+12°) treadmill. Shaded areas are stance; unshaded areas are swing. Mechanical energy production (positive power) in stance increased during incline versus level running for both the LG and PL, as muscle shortening increased over their periods of force production. During decline running, both the LG and PL shifted mechanical function and instead absorbed mechanical energy in stance by forcefully lengthening. L, fascicle length; L₀, resting segment length.