Fig. 3. Change in length of a depressor mandibulae muscle vs time during a load-clamp experiment. When the load is reduced (t=0), the muscle exhibits a fast phase of shortening and a slow phase of shortening with oscillations during the transition. To define the fast to slow phase transition (red circle), a line representing shortening during the slow phase, and bisecting the oscillations, was extrapolated back to its initial intersection with the length trace. Fast phase displacement is defined as the change in length that occurs from the initial position (t=0) to this point of intersection. This trace corresponds to Ba 1 (F=2.82) in Fig. 8B.