Abstract OBJECTIVE: To investigate whether athletic participation allows master athletes to preserve their good bone health into old age. METHODS: Bone strength indicators of the tibia and the radius were obtained of master runners and race-walkers (n=300) competing at World and European Master Championships and of 75 sedentary controls, all aged 33-94 yrs. RESULTS: In the tibia, diaphyseal cortical area (Ar.Ct), polar moment of resistance (RPol) and trabecular bone mineral density (vBMD) were generally greater in athletes than controls at all ages. In the athletes, but not the controls, Ar.Ct, RPol (females) and trabecular vBMD were negatively correlated with age (p<0.01). Radius measures were comparable between athlete and control groups at all ages. The amalgamated data revealed negative correlations of age with Ar.Ct, RPol (females), cortical vBMD and trabecular vBMD (males; p<0.005) and positive correlations with endocortical circumference (p<0.001). CONCLUSION: This cross-sectional study found age-related differences in tibial bone strength indicators of master athletes, but not sedentary controls, thus, groups becoming more similar with advancing age. Age-related differences were noticeable in the radius too, without any obvious group difference. Results are compatible with the notion that bones adapt to exercise-specific forces throughout the human lifespan.