The osteogenic effect of impact-loading and resistance exercise on bone mineral density in middle-aged and older men: a pilot study
Background: Regular exercise has been recommended as a potential strategy to counteract the age-related bone loss experienced by men; however, the optimal exercise prescription is not known. Objective: To perform a pilot study to examine the osteogenic effect, safety and feasibility of a combined program of upper body resistance exercise and two doses of impact-loading exercise on bone mineral density (BMD) of middle-aged and older men. Methods: Fortytwo community-dwelling men aged 50-74 years were randomly assigned to either an exercise program of combined upper body resistance exercise and either high-dose impactloading (HI; 80 jumps per session) or moderate-dose impactloading (MOD; 40 jumps per session) or a control (CON) group. The 9-month intervention involved 4 sessions each week: 2 supervised clinic-based and 2 home-based. BMD of the lumbar spine, femoral neck, total hip, trochanter and whole body as well as lean and fat mass were assessed at baseline and 9 months by dual-energy X-ray absorptiometry. Bone turnover markers, hormone levels, physical function and muscle strength were also assessed. Results: Following 9 months of training, significant differences in BMD among groups were found at the total hip (p = 0.010) and trochanter (p = 0.047) with BMD in the MOD group decreasing relative to the HI group. Although not significant, the HI group consistently preserved BMD, whereas BMD of the MOD and CON groups declined at the hip sites. Mean change for all groups at all skeletal sites was approximately within +/- 1%. There was no change in bone turnover markers. There were no adverse events as a result of the intervention; however, overall attendance for the HI and MOD groups was 53% (clinic: 68%, home: 38%) and 65% (clinic: 74%, home: 55%), respectively. Conclusions: This study indicates that while impact-loading exercise can be safely undertaken in middle-aged and older men, the current combined program did not elicit significant improvements in BMD.