A: anterior crural muscle relaxation rates of peak isometric torques assessed during bouts 1 and 5. *P < 0.001, bout 5 > bout 1. B: representative Western blots probed for sarco(endo)plasmic reticulum Ca2+-ATPase 1a (SERCA1a), parvalbumin, and GAPDH for control (C) and injured (I) muscles. C: comparisons of protein contents between contralateral control and in vivo-injured muscles from 1 bout +3 (1 bout) and 5 bouts +full (5 bouts) mice. All protein contents were normalized to GAPDH and are shown relative to contralateral control muscles for each group, respectively. *P = 0.038, greater than the contralateral control muscle.