Effects of 8 Weeks of Training with Different Exercise Intensities on NOS (Nitric Oxide Synthase)-Related Factors in the Skeletal Muscle of Aged Rats

This study investigated the effects of eight weeks of treadmill training with different exercise intensities on the expression of eNOS, nNOS, iNOS, and PGC-1α in the skeletal muscles of aged rats. Twenty eight 72week old male Sprague-Dawley rats were randomly divided into four groups: a sedentary control group and three exercise groups that performed low(15m/min), moderate(20m/min), or high-intensity(25m/min) running, five days per week. After the training period, gastrocnemius muscles were collected, and protein expression levels were quantified using Western blotting. The results showed that the high-intensity group exhibited the greatest increases in eNOS and PGC-1α expression, while nNOS expression reached the highest level in the same group. In contrast, all exercise groups showed a decreasing tendency in iNOS expression compared with the control. These findings suggest that high-intensity aerobic exercise optimally enhances nitric oxide production and mitochondrial biogenesis in the aging skeletal muscle.