Effect of exercise on strength and chemical composition of rat femur bone

The effect of exercise on strength and chemical composition of rat femur bone was examined. Ten 5-week-old rats were forced to exercise on a treadmill with a running speed of 20 m/min at set time intervals for a 4-week period. Another 10 rats were kept idle as controls. After exercising, bending tests of the rat femur bones were carried out, and the content ratios of Sr to Ca, Sr/Ca, were measured by energy-dispersive fluorescent X-ray analysis and EPMA line analysis. The strength of the exercise group was greater than that of the control group. The ratio, Sr/Ca, of the exercise group showed a tendency to increase compared to that of the control group. It is clear that the chemical composition of bone varies with the degree of exercise, and that the bone becomes strengthened at the same time.