Effect of exercise modality and weight loss on changes in muscle and bone quality in older adults with obesity
Diana Madrid, Kristen M. Beavers, Michael P. Walkup, Walter T. Ambrosius, W. Jack Rejeski, Anthony P. Marsh, Ashley A. Weaver
Abstract
Little is known about the effect of exercise modality during a dietary weight loss program on muscle size and quality, as measured by computed tomography (CT). Even less is known about how CT-derived changes in muscle track with changes in volumetric bone mineral density (vBMD) and bone strength. Older adults (66 ± 5 years, 64 % women) were randomized to 18-months of diet-induced weight loss (WL), WL with aerobic training (WL + AT), or WL with resistance training (WL + RT). CT-derived muscle area, radio-attenuation and intermuscular fat percentage at the trunk and mid-thigh were determined at baseline (n = 55) and 18-month follow-up (n = 22–34), and changes were adjusted for sex, baseline value, and weight lost. Lumbar spine and hip vBMD and finite element-derived bone strength were also measured. After adjustment for the weight lost, muscle area losses at the trunk were −7.82 cm2 [−12.30, −3.35] for WL, −7.72 cm2 [−11.36, −4.07] for WL + AT, and −5.14 cm2 [−8.65, −1.63] for WL + RT (p < 0.001 for group differences). At the mid-thigh, decreases were −6.20 cm2 [−10.39, −2.02] for WL, −7.84 cm2 [−11.19, −4.48] for WL + AT, and −0.60 cm2 [−4.14, 2.94] for WL + RT; this difference between WL + AT and WL + RT was significant in post-hoc testing (p = 0.01). Change in trunk muscle radio-attenuation was positively associated with change in lumbar bone strength (r = 0.41, p = 0.04). WL + RT better preserved muscle area and improved muscle quality more consistently than WL + AT or WL alone. More research is needed to characterize the associations between muscle and bone quality in older adults undertaking weight loss interventions.