Osteoprotective benefits of exercise: more pain, less gain?

Based on the results of their study, Hagberg et al. suggested that physical activity that is moderate in intensity might be most appropriate for the prevention of osteoporosis in postmenopausal women. The take-home message is that being physically active has osteoprotective benefits. However, the implication that more vigorous exercise is less beneficial must be carefully scrutinized. When compared with the physically active nonathletes, the highly trained athletes in this study tended to be more years beyond menopause, had been on HRT for a smaller proportion of the postmenopausal period, and may have had lower endogenous estrogen levels as a result of having less fat mass. The chronic exposure of the skeleton to estrogens very likely played a more prominent role in determining BMD status in the women in this study than the investigators were able to ascertain, owing largely to the cross-sectional nature of the investigation. It is safe to conclude that an exercise prescription for the prevention of osteoporosis should include weight-bearing exercise, but the optimal intensity, frequency, and duration of exercise remain to be established. The results of the study by Hagberg et al. emphasize the importance of physical activity for sustaining BMD, but should not provide a basis for discouraging women from performing vigorous exercise.