Fig. 1

Experimental device and protocol for passive muscle stretch in a rat model of muscle injury induced by lengthening contractions (LC). A A customized experimental device for passive muscle stretch and isometric torque measurement, consisting of: a a footplate attached to the paw, b a rotary stepping motor, c a control box for driving signals from a computer, d a torque sensor. B Joint-angle settings for passive muscle stretch (i.e., starting position). C Original recording of passive torque elicited during muscle stretch (3 mNm for 15 min). D Enlarged image of the torque curve corresponding to 5 muscle stretches (asterisk in C). Muscle stretch was performed at a stretch velocity of 50°/s for 5 s, followed by a 5-s rest period. E Torque generated during passive stretch at the velocity of 50°/s and various stretch angles. n = 3 rats