Cross-sectional and longitudinal studies on the effect of water exercise in controlling bone loss in Japanese postmenopausal women.

The effects of water exercise, as a form of daily physical activity (water exercise in a warm water pool), on bone loss in healthy Japanese postmenopausal women have been cross-sectionally and longitudinally investigated from the viewpoint of preventing osteoporosis. In the cross-sectional study, the bone mineral density (BMD) of the lumbar spine (Z-score (%)) in the Veterans group (N = 27), who had been exercising for 35.2 months on average, was significantly higher than that in the Newcomers (N = 40), who had only begun to exercise 3 or 4 weeks before, and that in the Non-exercisers (N = 30), serving as a control group. The rate of change in the BMD of the lumbar spine was -0.92%/year in the Non-exercisers (N = 30), +1.55%/year in the Veterans (N = 20), and +2.16%/year in the Newcomers (N = 15), based on BMD Z-scores. In the Exercisers groups, it was found that the rate of change in the BMD showed a slight increase rather than a decrease irrespective of the duration of menopause. On the other hand, in the Non-exercisers group, the rate of change in the BMD decreased slightly. The results of questionnaires showed that the subjects' general awareness of health and fitness in daily life was enhanced after starting the water exercise program. These results suggest that consistently participating in water exercise is an important factor in preventing bone loss, and moreover, appears not only to indirectly improve awareness of daily physical activity but also to promote health and improve daily life.