Constant adaptation of bone to current physical activity level in men: a 12-year longitudinal study.

Abstract

A high peak bone mineral density (BMD; grams per square centimeter) could reduce the risk of osteoporosis related fractures later in life. This 12-yr longitudinal study investigated whether a high BMD from previous high physical activity is maintained with reduced activity later in life. This was a longitudinal study. Three groups were investigated with a mean age of 17 yr at baseline; 51 athletes who stopped their active careers during follow-up (former athletes), 16 who were active throughout follow-up (active athletes), and 25 controls. BMD of the femoral neck, total body, and lumbar spine were examined five times during the 12-yr follow-up period. After adjustment for age, weight, and height, the former athletes were found to have higher BMD at all sites at every follow-up visit except the last one, when compared with controls (P < 0.05). The active athletes were found to have significantly higher BMD at all measured locations when compared with controls throughout the entire study (P < 0.05). From the first to the final follow-up visit, the former athletes were found to have lost more femoral neck BMD than both the active athletes (mean difference, 0.12 g/cm(2); P = 0.003) and controls (mean difference 0.08 g/cm(2); P = 0.02). This study suggests that BMD constantly adapts to the present physical activity levels in young men. Thus, increased BMD due to previous high physical activity may not prevent osteoporosis in later years.