Exercise induced changes in the energy expenditure of female Wistar rats.

Changes in body weight and energy expenditure following exercise training was assessed in female Wistar rats. Rats were trained to swim in a tank filled with water for 2 hr everyday, 6 days a week. Changes in energy intake and body weight were recorded. The resting metabolic rate (RMR) was measured by indirect calorimetry and the capacity for non shivering thermogenesis (NST) was determined by measuring the stimulated oxygen consumption following a sc injection of norepinephrine (250 micrograms/kgbw). The RMR of exercised rats was 14% higher and the capacity for NST was 22% higher than that of sedentary rats. Energy intake of the exercised rats increased significantly while the body weights were maintained at levels comparable to that of the sedentary rats. Results indicate that body weight regulation is achieved by increasing food intake in response to the increased energy expenditure due to forced exercise as well as the stimulatory effect of exercise on RMR and NST.