Physical activity reduces bone loss in the distal forearm in post-menopausal women--a 25-year prospective study

Intervention studies have shown that high-intensity training programs with duration of 1-3 years can influence bone mass in post-menopausal women. We wanted to investigate whether moderate physical activity could be associated with reduced post-menopausal bone loss also in the long-term perspective. We evaluated changes in bone mass and bone structure by repeated single-photon absorptiometry measurements of the distal forearm in 91 moderately physically active and 21 inactive women, categorized according to information from questionnaires, from menopause and on average 25 years onwards. Data were calculated with analysis of variance and analysis of covariance tests and presented as means with 95% confidence interval. There were no group differences in bone mass or bone structure at menopause. The mean annual loss in bone mineral content was 1.2% (1.1, 1.3) in the physically active and 1.6% (1.3, 1.8) in the inactive women (after adjustment for menopausal age P = 0.02) and the mean decline in a strength index based on bone mass and bone structure was 0.7% (0.6, 0.8) in the physically active and 1.2% (0.8, 1.5) in the inactive women (P = 0.004). There were no group differences in the changes in bone structure. Physical activity is also in a long-term perspective associated with reduced post-menopausal bone loss.