Resistance exercise alone or in combination with aerobic exercise was found to be better than aerobic exercise alone in reducing weight loss-induced decreases in hip bone mineral density (BMD) in adults with obesity, according to study results published in the Journal of Bone and Mineral Research.
Previous studies have reported that weight loss may potentially worsen muscle and bone mass in adults, leading to increased fracture risk. Regular exercise is recommended to prevent this negative consequence of weight loss. The goal of the current study was to compare different exercise types in preventing weight loss-induced reductions in BMD.
The study was based on data from 160 participants aged ≥65 years in the Lifestyle Intervention Trial in Obese Elderly, a randomized controlled trial that evaluated the relative efficacy of various modes of exercise for physical function and frailty improvement in adults with obesity over a 6-month weight-loss intervention.
Individuals were randomly assigned to 1 of 4 groups: (1) a control group that was not assigned an exercise intervention but attended educational sessions about healthy eating, (2) an aerobic exercise training group with a weight-loss intervention, (3) a resistance exercise training group with a weight-loss intervention, or (4) a group that received combined training for aerobic and resistance exercise with a weight-loss intervention.
At 6 months, BMD at the total hip decreased less in the resistance exercise group (-0.006 g/cm2; -0.7%) and the combined aerobic and resistance exercise group (-0.012 g/cm2; -1.1%) compared with the aerobic exercise group (-0.027 g/cm2; -2.6%; P =.001 for between-group comparisons).
The researchers noted a significant increase in bone turnover markers in the aerobic exercise group, but no significant changes in the resistance and combined aerobic and resistance exercise groups. Compared with the resistance or combined exercise groups, the aerobic group had significantly greater increases in serum C-terminal telopeptide of type 1 collagen (+7%, +11%, and +33%, respectively), procollagen type 1 N-terminal propeptide (+2%, +2%, and +16%, respectively), and osteocalcin (0%, +5%, and +16%, respectively).
The study had several limitations. First, no assessment of bone quality was available, and it is possible that the combination of weight loss and exercise in older adults could have beneficial effects on bone quality despite possible declines in BMD. Second, the short follow-up period precluded assessment of the effects of weight loss and exercise on falls and fractures. Third, the small sample size did not allow for assessment of potential sex differences in BMD changes.
“[W]eight loss plus combined aerobic and resistance exercise not only optimally improves physical function but also protects against bone loss during weight loss therapy of the increasing number of older adults with obesity in the US and other more developed countries,” concluded the researchers.
Armamento-Villareal R, Aguirre L, Waters DL, Napoli N, Qualls C, Villareal DT. Effect of aerobic or resistance exercise, or both, on bone mineral density and bone metabolism in obese older adults while dieting: a randomized controlled trial [published online December 4, 2019]. J Bone Miner Res. doi:10.1002/jbmr.3905