Bouts of exercise and food intake in the rat.

Abstract

The effect of regular and irregular enforced exercise (treadmill and swimming) on the food intake, weight gain, and, in some cases, spontaneous activity of adult male Sprague-Dawley rats was observed. Regular enforced running for 4 consecutive days a week caused a reduction in these functions with some increase on the days free of exercise. Enforced swimming for 2 hr or less/day had a similar effect but swimming for 4 hr/day did not reduce food intake. All swimming groups showed less proportionate decrease in food intake than the controls in response to a hot environment. Rats exposed to irregular bouts of enforced treadmill or swimming exercise every 3rd or 4th day decreased food intake on that day with an increase on the 1st or 2nd day following. The reduction and subsequent increase of food intake were even more prominent in rats trained to eat their daily food in 3 hr/day. This response of rats to enforced exercise, reminiscent of that observed by some in man, does not appear to be explained by current hypotheses of the control of food intake.