The effects of long-term, light exercise under restricted feeding on age-related changes in physiological and metabolic functions were examined in male Wistar rats. Adult (100 days old) rats were divided into sedentary (R10S) and exercise (R11E) groups, and given 10 and 11 g/day, respectively, of a 20% casein diet until they reached 900 days of age. Group R11E simultaneously underwent 3000 m/day of running exercise throughout the test period. As compared with the sedentary group, long-term, light exercise significantly increased body nitrogen retention and serum protein levels, decreased body fat and plasma insulin levels, prevented age-related decline in the basal metabolic rate, and reduced age-associated histopathological changes in the kidney and liver. Long-term, light exercise further enhanced the benefits of restricted feeding on age-related deterioration in physiological and metabolic variables and improved body composition, but did not prolong survival at 900 days of age.