Bone mass following physical activity in young years: a mean 39-year prospective controlled study in men

This is a study on exercise-associated bone mineral density (BMD) which in men is maintained three decades after cessation of sports. In this prospective controlled cohort study active athletes had a BMD Z-score of 1.0 and after 39 years 0.5 to 1.2 depending on the measured region), using the same single-photon absorptiometry device, dual X-ray absorptiometry (DXA), and peripheral computed tomography (pQCT). The aims of this study were to prospectively evaluate BMD changes in male athletes from activity into long-term retirement and to simultaneously evaluate other bone traits. Bone mineral density (grams per square centimeter) was measured in 46 male athletes with a mean age of 22 years (range, 15-40) by using the same single-photon absorptiometry device, both at active career and a mean of 39 years (range, 38-40) later when they had long-term retired. At follow-up, BMD was also evaluated by DXA and pQCT. Twenty-four non-athletic males of similar age served as controls. Between-group differences are presented as means with 95 % confidence intervals. The active athletes (baseline) had a BMD Z-score of 1.0 (0.7, 1.4) in the femoral condyles. The retired athletes (follow-up) had a BMD Z-score of 0.5 to 1.2 depending on the measuring technique and the measured region. The tibial cortical area Z-score at follow-up was 0.8 (0.5, 1.2) and the tibial strength index Z-score 0.7 (0.4, 1.0). There were no changes in BMD Z-scores from activity to retirement, neither when estimated by the same device in different regions [a dagger Z-score -0.3 (-0.8, 0.2)] nor in the same region with different devices [a dagger Z-score 0.0 (-0.4, 0.4)]. The benefits remained after adjustments for anthropometrics and lifestyle. No correlation was seen with years since retirement. Exercise-associated high BMD in young years seems, in men, to be maintained three decades after cessation of high-level physical activity.