Do Changes in Body Composition Contribute to Decline in Muscle Strength? The BACH/Bone Study

Abstract

BackgroundDecline in muscle strength is a risk factor for dependence and disability in older persons. The role of changes in body composition on muscle strength decline is unclear. The aim of this study was to examine the relationship between changes in lean and fat mass on decline in muscle strength in a racially diverse population of men.MethodsThis study included 692 black, Hispanic, and white men aged 30‐80y participating to the baseline and 8‐y follow‐up assessments of the population‐based longitudinal Boston Area Community Health/Bone Survey. Fat and lean mass were measured by dual‐energy x‐ray absorptiometry, and muscle strength by hand dynamometer. Multivariable linear regression models were used to determine the marginal mean change in muscle strength according to decline in fat or lean mass.ResultsThere was a significant difference in change in muscle strength in men who declined in fat mass during 8‐y follow‐up compared to those who did not decline (p=.009; mean change for no decline= ‐.06; 95%CI:‐.24,0.12; mean change for decline: ‐.47, 95%CI:‐.72,‐.22). Differences in muscle strength were not statistically significant for decline in lean mass (p=.26; mean change for no decline=‐.17; 95% CI: ‐.38, .04; mean change for decline=‐.34; 95% CI: ‐.55,‐.12). The results did not substantially change after mutual adjustment for fat mass and lean mass at baselineConclusionsIn men, decline in fat mass contributes to decline in muscle strength independently of lean mass. These results suggest that adipose tissue‐related factors (e.g. endocrine function) may play a role on muscle strength decline in middle‐aged and older men.