Bone loss and fracture risk after reduced physical activity

Abstract

Former male young athletes partially lost benefits in BMD (g/cm 2) with cessation of exercise, but, despite this, had a higher BMD 4 years after cessation of career than a control group. A higher BMD might contribute to the lower incidence of fragility fractures found in former older athletes ≥60 years of age compared with a control group. Introduction: Physical activity increases peak bone mass and may prevent osteoporosis if a residual high BMD is retained into old age. Materials and Methods: BMD was measured by DXA in 97 male young athletes 21.0 ± 4.5 years of age (SD) and 48 controls 22.4 ± 63 years of age, with measurements repeated 5 years later, when 55 of the athletes had retired from sports. In a second, older cohort, fracture incidence was recorded in 400 former older athletes and 800 controls ≥60 years of age. Results: At baseline, the young athletes had higher BMD than controls in total body (mean difference, 0.08 g/cm2), spine (mean difference, 0.10 g/cm2), femoral neck (mean difference, 0.13 g/cm2), and arms (mean difference, 0.05 g/cm2; all p < 0.001). During the follow-up period, the young athletes who retired lost more BMD than the still active athletes at the femoral neck (mean difference, 0.07 g/cm2; p = 0.001) and gained less BMD at the total body (mean difference, 0.03 g/cm2; p = 0.004). Nevertheless, BMD was still higher in the retired young athletes (mean difference, 0.06-0.08 g/cm 2) than in the controls in the total body, femoral neck, and arms (all p < 0.05). In the older cohort, there were fewer former athletes ≥60 of age than controls with fragility fractures (2.0% versus 4.2%; p < 0.05) and distal radius fractures (0.75% versus 2.5%; p < 0.05). Conclusions: Although exercise-induced BMD benefits are reduced after retirement from sports, former male older athletes have fewer fractures than matched controls.