Inability of myoglobin to increase in dystrophic skeletal muscle during daily exercise.

An exercise program consisting of 80-min daily runs on a treadmill was performed by normal and dystrophic hamsters. Subgroups were sacrificed at various times during the 45-day program. Daily exercise resulted in a significant increase in the myoglobin concentration of gastrocnemius muscles in normal animals but not in dystrophic animals. In the exercise groups of hamsters, there were significant increases in the concentration of cytochrome c, a marker for respiratory capacity, in the gastrocnemius of both normal and dystrophic hamsters.