Effect of six weeks of resistance training on bone preservation in older adults: a randomized control trial.

BACKGROUND: It has been established that chronic resistance exercise contributes to positive changes to bone in older adults.

AIMS: This study evaluated the effect of 6 weeks of resistance exercise with either elastic bands or dumbbells vs. a control period on bone morphology of older adults.

METHODS: Fifty-seven adults (mean ± SD; age = 66.5 ± 7.09 yrs; height = 165.2 ± 10.6 cm; body mass = 74.5 ± 14.6 kg) were randomized into three groups (dumbbell, elastic, or control). Participants underwent a total body dual-energy X-ray absorptiometry (DXA) scan for total body and segmental bone mineral content (BMC) and bone mineral density (BMD) before and following 6-week intervention. Age-matched Z-scores for BMD and BMC were recorded. Data were analyzed using two-way repeated measures ANOVAs and 0.05 significance level.

RESULTS: BMCarm improved for the dumbbell group (p = 0.016) after the training, with no change in BMD for any group (p > 0.05). Additionally, significant (time x treatment group) interaction (p = 0.024) of age-matched Z-scores indicated an improvement in only the dumbbell group after 6 weeks (p = 0.015), with no change in the elastic group despite them having greater Z-scores than the control group.

DISCUSSION: This study is the first to demonstrate acute normative adaptations as dumbbell-based programs may promote positive maintenance of bone metrics over 6 weeks, despite the lack of significant change in absolute BMC or BMD.

CONCLUSION: Adults did not lose relative bone mass with acute exercise using dumbbells as the external load applied and this may lead to positive changes following chronic training. There was no bone-related impact from elastic bands, suggesting a weighted load or force produced relative to gravity is beneficial.