Tibial and Fibular Mid-Shaft Bone Traits in Young and Older Sprinters and Non-Athletic Men

High impact loading is known to prevent some of the age-related bone loss but its effects on the density distribution of cortical bone are relatively unknown. This study examined the effects of age and habitual sprinting on tibial and fibular mid-shaft bone traits (structural, cortical radial and polar bone mineral density distributions). Data from 67 habitual male sprinters aged 19-39 and 65-84 years, and 60 non-athletic men (referents) aged 21-39 and 65-80 years are reported. Tibial and fibular mid-shaft bone traits (strength strain index SSI, cortical density CoD, and polar and radial cortical density distributions) were assessed with peripheral quantitative computed tomography. Analysis of covariance (ANCOVA) adjusted for height and body mass indicated that the sprinters had 21 % greater tibial SSI (P < 0.001) compared to the referents, with no group x age-group interaction (P = 0.54). At the fibula no group difference or group x age-group interaction was identified (P = 0.12-0.81). For tibial radial density distribution ANCOVA indicated no group x radial division (P = 0.50) or group x age-group x division interaction (P = 0.63), whereas an age x radial division interaction was observed (P < 0.001). For polar density distribution, no age-group x polar sector (P = 0.21), group x polar sector (P = 0.46), or group x age-group x polar sector interactions were detected (P = 0.15). Habitual sprint training appears to maintain tibial bone strength, but not radial cortical density distribution into older age. Fibular bone strength appeared unaffected by habitual sprinting.