Effects of a 20-week high-intensity strength and sprint training program on tibial bone structure and strength in middle-aged and older male sprint athletes : a randomized controlled trial

Summary This randomized, controlled, high-intensity strength and sprint training trial in middle-aged and older male sprint athletes showed significant improvements in mid-tibial structure and strength. The study reveals the adaptability of aging bone, suggesting that through a novel, intensive training stimulus it is possible to strengthen bones during aging. Introduction High-load, high-speed and impact-type exercise may be an efficient way of improving bone strength even in old age. We evaluated the effects of combined strength and sprint training on indices of bone health in competitive masters athletes, who serve as a group of older people who are likely to be able to participate in vigorous exercise of this kind. Methods Seventy-two men (age 40–85) were randomized into an experimental (EX, n = 40) and a control (CTRL, n = 32) group. EX participated in a 20-week program combining heavy and explosive strength exercises with sprint training. CTRL maintained their usual, run-based sprint training schedules. Bone structural, strength and densitometric parameters were assessed by peripheral QCT at the distal tibia and tibial midshaft. Results The intervention had no effects on distal tibia bone traits. At the mid-tibia, the mean difference in the change in cortical thickness (ThCO) in EX compared to CTRL was 2.0% (p = 0.007). The changes in structure and strength were more pronounced in the most compliant athletes (training adherence >75%). Compared to CTRL, total and cortical cross-sectional area, ThCO, and the area and density-weighted moments of inertia for the direction of the smallest flexural rigidity (I minA , I minD ) increased in EX by 1.6–3.2% (p = 0.023–0.006). Polar mass distribution analysis revealed increased BMC at the anteromedial site, whereas vBMD decreased (p = 0.035–0.043). Conclusions Intensive strength and sprint training improves mid-tibia structure and strength in middle-aged and older male sprint athletes, suggesting that in the presence of high-intensity loading exercise, the adaptability of the bone structure is maintained during aging.