Systemic and mitochondrial adaptive responses to moderate exercise in rodents

The systemic and nonmuscular adaptive response to moderate exercise is reviewed and compared with muscle responses to moderate and exhaustive exercise. Rats participating in voluntary wheel running and mice subjected to treadmill exercise on a lifelong basis showed 10–19% increased median life span. Mice also showed improved neurological functions, such as better (35–216%) neuromuscular coordination (tightrope test) and better (11–27%) exploratory activity (T maze). These effects are consistent with the systemic effects of moderate exercise lowering hyperglycemia, hypercholesterolemia, and hypertension. Mitochondria isolated from brain, liver, heart, and kidney of exercised mice show a 12–32% selectively increased complex IV activity, with a significant correlation between complex IV activity and performance in the tightrope test. Chronic exercise decreases (10–20%) the mitochondrial content of TBARS and protein carbonyls in the four organs after 24 weeks of training. Protein carbonyls were linearly and negatively related to complex IV activity. Exercise increased the levels of nNOSμ in human muscle and of nNOS in mouse brain. It is concluded that chronic moderate exercise exerts a whole-body beneficial effect that exceeds muscle adaptation, likely through mechanosensitive afferent nerves and β-endorphin release to brain and plasma that promote mitochondrial biogenesis in distant organs.