Six-weeks Of Resistance Training Is Not Sufficient To Stimulate Bone Response In Older Adults

Abstract

Aging presents a variety of challenges, ranging from loss of muscle mass, strength, and bone density to functional impairment, risk of fall and fracture. Resistance exercise is known to load the bone and enhance bone density and subsequently strength. However these adaptation typically occur over a long period of time (6+ months). PURPOSE: The purpose of this study was to evaluate whether either dumbbell or elastic band resistance training are beneficial in bone morphology of older adults over 6 weeks of training or a control period. METHODS: Fifty-seven males and females (mean ± SD; age = 66.5 ± 7.09 yrs; height = 165.2 ± 10.6 cm; body mass = 74.5 ± 14.6 kg) volunteered to participate in this study. Participants underwent a total body dual-energy x-ray absorptiometry (DXA) scan for segmental and total body bone mineral content (BMC) and bone mineral density (BMD). Participants were block randomized into one of three groups: elastic band resistance training (EBRT; n = 24), dumbbell resistance training (DBRT; n = 21), or control (CON; n = 12). EBRT and DBRT were asked to visit the laboratory twice weekly over 6-weeks while CON maintained their daily routine. Three-day dietary recalls were collected to ensure dietary maintenance throughout the intervention period. Data were analyzed using a two-way (time x treatment) repeated measures ANOVA and an alpha pre-determined at 0.05. RESULTS: Results indicated there was no two-way interaction for total body BMC (p = 0.164) nor was there a main effect for time (p = 0.39) or group (p = 0.40). Likewise, total body BMD indicated no 2-way interaction (p = 0.79) and no main effect for time (p = 0.753). However, there was a main effect for group where collapsed across time, DBRT had a higher BMD than CON (p = 0.05), but no other differences were observed. CONCLUSIONS: These data suggest that either the load provided throughout the training from DBRT and EBRT to stimulate change in bone over 6-weeks was insufficient or the duration was not long enough. Most previous research supports the latter as bone remodeling occurs in a throughout 4-8 month periods. Other factors that may impact the outcome of the stimuli include exogenous pharmacological treatment for bone loss and dietary factors.