Physical rehabilitation in the form of voluntary wheel running exacerbates chronic injury in the injured muscle. Uninjured contralateral (not shown) and injured muscle of the SED (A) and RUN (B) groups were analyzed for the presence of centrally located nuclei (white arrows) (Scale bar = 100 μm). Inset images are high magnification (200×) images in the injured muscle (Scale bar = 50 μm). Physical rehabilitation significantly increased the presence of CLN in the injured muscle (C). Values are mean ± SEM. n = 6 /group; * denotes ≠ uninjured (contralateral); § denotes ≠ sedentary injured; p < 0.05.