| Experiments were undertaken to examine the effect of acute and chronic exercise on some metabolic, histochemical, and morphological properties of rat plantaris (PM) and soleus (SM) muscles. Some animals had their PM and SM enlarged via surgical ablation of the gastrocnemius (GM) muscle. The weights of PM from sedentary and trained rats with ablation of the GM were 68 and 92% greater (P < 0.01), respectively, than those of sedentary normal animals. The weights of SM from sedentary and trained rats with ablation of the GM were 32 and 45% greater (P < 0.01), respectively, than those of normal animals. Training resulted in a 50% greater (P < 0.01) succinate dehydrogenase (SDH) activity in both the normal and enlarged PM and Sm. Hexokinase and phosphorylase activities were unchanged by any combination of experimental perturbations. An acute bout of treadmill running resulted in no change in the fiber composition of the rat SM. These data evince that the response of severely enlarged skeletal muscle to training is similar to that of normal muscle and that a single bout of exercise educes no effect on the fiber composition of skeletal muscle. |
