Obesity Status and Moderate-to-Vigorous Physical Activity Influence Physical Function in Community-Dwelling Older Adults

Abstract

Aging is accompanied by a progression reduction in lean mass, gains in adiposity, and reductions in physical activity. Similarly, aging is associated with detriments in physical function, including gait and balance. Gaining a better understanding of the influences of body composition and physical activity on physical function is imperative for prevention and treatment of mobility disability. PURPOSE: The primary purpose of this study was to determine the influence of body composition components (adiposity and mineral-free lean mass (MFLM)) and moderate-to-vigorous physical activity (MVPA) on measures of lower-extremity physical function (LEPF) in community-dwelling older adults. METHODS: Older adults (N=156, age=68.9±6.7 years, 85 men) were assessed for adiposity (%Body Fat) and relative muscle mass (Skeletal Muscle Index (SMI); appendicular MFLM/ht2) via dual-energy X-ray absorptiometry, and total and MVPA using accelerometers. LEPF was assessed by 7-m walk tests, a Timed Up and Go (Up&Go), a 30-second chair stand test (30-Chair), a 6-min walk, the Short Physical Performance Battery (SPPB) and the Star-Excursion Balance Test (STAR) in the anterior (ANT), medial (MED) and posterior (POST) directions. RESULTS: Men performed better on all LEPF tests (all p<0.05). Unlike all other independent variables, SMI was not related to any LEPF outcomes. With no significant interactions between %Body Fat and MVPA on gait-related tests (all p>0.25), main effects for adiposity were found for all LEPF, with no main effect of PA. On STAR balance tests, an interaction existed for POST and composite reaches (p<0.05). After accounting for influences of sex, age and total medication usage %Body Fat remained a significant predictor of all LEPF measures. CONCLUSIONS: Our results suggest that adiposity is a major determinant of both balance and gait-related physical function in relatively healthy older adults. Physical activity may help to prevent age-related loss of balance, but appears to be less important than adiposity in relation to mobility.