[The effect of physical exercise in experimental osteoporosis rats].

The effect of physical exercise on the growth of bones was studied. Male rats 8 weeks old were divided into 3 groups, a sedentary group and 2 exercise groups (RUN 1, RUN 2). Rats in the exercised groups were conditioned by a treadmill running program for 8 weeks (RUN 1, 1 hr X 1/day; RUN 2, 1 hr X 2/day). Animals in the RUN 2 group showed remarkably increased cortical thickness and density by the microdensitometry method and greater dry weight. Female rats in the similar running program showed the effective change in only RUN 1 group. To evaluate the protective effect of physical exercise on the loss of bone mass in experimental osteoporosis, 6 week old rats were bilaterally ovariectomized, fed a low Ca diet and exercised on a treadmill. Ovariectomized-exercised bones were higher in cortical thickness, density, area and dry weight than the ovariectomized-unexercised group. These results support the view that suitable physical exercise may be a valuable treatment for postmenopausal osteoporosis in human beings.