Food intake, body composition and blood lipids following treadmill exercise in male and female rats

Body weight gain, food intake, body composition and blood lipids of male and female Osborne Mendel rats were compared on the same exercise treadmill program. To mimic their nocturnal habits, rats were exercised daily at the beginning of the 12 hour dark cycle and food intake was measured for both light and dark cycles. After a 10 day treadmill adaptation period, the duration of exercise was successively increased over a 12 day period until 60 min/day at 21.3 meters/min was reached. Relative to their respective controls, exercised male rats showed a reduction in body weight and light cycle food intake while female runners showed no change in body weight or food intake. Exercise resulted in a decrease in percent body fat in both males and females while only male runners increased percent protein. Both males and females reduced serum triglycerides while serum cholesterol was reduced only in the males. The short term exercise program produced highly significant changes in the males while the females were more resistant to the same exercise regimen.