The effects of voluntary activity initiated in adult mdx (C57BL/10ScSc-DMDmdx /J) mice on skeletal and cardiac muscle function have not been studied extensively. Here, the authors studied the effects of 3 months of voluntary wheel running initiated at age 7 months on hindlimb muscle weakness, increased susceptibility to muscle contraction-induced injury, and left ventricular function in mdx mice. Voluntary wheel running did not worsen the deficit in force generating capacity and the force drop following lengthening contractions in both mdx mouse genders. It increased the absolute maximal force of skeletal muscle in female mdx mice. Moreover, it did not affect left ventricular function, structural heart dimensions, cardiac gene expression of inflammation, fibrosis, or remodeling markers. These results indicate that voluntary activity initiated at age 7 months has no detrimental effects on skeletal or cardiac muscles in both mdx mouse genders.
