Exercise and food restriction in rats.

A number of studies have shown that exercised rats live longer than sedentary freely eating controls. There is disagreement regarding whether exercise results in extension of maximal life span. However, in two studies of the effect of voluntary wheel running on longevity of male specific-pathogen-free Long-Evans rats it was found that, although the runners had a longer average survival than sedentary freely eating controls, they did not have an increase in maximal life span. This is in contrast to the effect of food restriction. Sedentary rats that were food restricted to keep their body weights in the same range as those of the runners lived longer than the runners and showed an extension of life span. When exercise, in the form of voluntary wheel running was combined with food restriction (approximately 30% below ad libitum), the runners had an increased mortality rate over the first approximately 50% of their mortality curve up to age approximately 900 d. However, in those food-restricted runners that survived past approximately 900 d survival became similar to that of food-restricted sedentary controls, with a similar increase in maximal life span. Thus, although exercise has a deleterious effect on food-restricted rats, it does not counteract the increase in maximal life span induced by food restriction.