The Effect of Low-Frequency Jump-Training on Bone Mass and Strength in the Ovariectomized Rats / 体力科学

ABSTRACT

The effect of low-frequency jump-training on bone was investigated in intact (Intact) and ovariectomized (OVX) rats. Rats were divided into the following three groups for each experiments sedentary (Intact-Sedentary and OVX-Sedentary), training once per week (Intact-1T and OVX-1T), and training three times per week (Intact-3T and OVX-3T) . The jump-training started at the age of 11 weeks for the Intact rats, and 12 weeks for the OVX rats, The jump-training protocol was 10 times day, 1 or 3 days week for 8 weeks, with a jumping-board height of 45 cm for the Intact experiment and 40 cm for the OVX experiment. After training, the fat-free dry weight, maximum breaking force, and bone morphometry in the right tibia were determined. The fat-free dry weight and maximum breaking force for the training groups in both experiments were significantly higher than those for the respective sedentary groups, though there were no significant differences between training groups. In the Intact experiment, the increases of cortical area at the tibia midlength in both training groups were especially remarkable. llowever in the OVX experiment, there were no significant differences between the sedentary and training groups in cross-sectional analysis. These results indicate that low-frequency jump-training had beneficial effects in term of increased bone mass and strength in the Intact rats and the OVX rats as well.