Beneficial effects of voluntary wheel running on the properties of dystrophic mouse muscle

Abstract

Effects of voluntary exercise on the isometric contractile, fatigue, and histochemical properties of hindlimb dystrophic (mdx and 129ReJ dy/dy) skeletal muscles were investigated. Mice were allowed free access to a voluntary running wheel at 4 wk of age for a duration of 16 (mdx) or 5 (dy/dy) wk. Running performance of mdx mice (~4 km/day at 1.6 km/h) was inferior to normal mice (~6.5 km/day at 2.1 km/h). However, exercise improved the force output (~15%) and the fatigue resistance of both C57BL/10 and mdx soleus muscles. These changes coincided with increased proportions of smaller type I fibers and decreased proportions of larger type IIa fibers in the mdx soleus. The extensor digitorum lo..