Adiposity and Physical Activity Influence Physical Function and Fatigue in Older Women

Abstract

Both physical activity and adiposity have been associated with functional performance and fatigue in the elderly; however, the relative impact of each is not established. PURPOSE: The aim of this study was to examine the independent contributions of physical activity and adiposity on physical function and fatigue in older community-dwelling women (N = 43; 69.7±6.1 yr). METHODS: Assessments included physical performance via 7-m obstacle walk (7-OB), chair stand (CHAIR) and 6 min walk (WALK); general, physical and mental fatigue via the Multidimensional Fatigue Inventory (MFI); physical activity by weekly pedometer count (STEPS); and adiposity (%Fat) by DXA. RESULTS: As expected, an inverse relationship existed between STEPS and %Fat (r=-0.38, p=0.01) and greater STEPS improved 7-OB, CHAIR and WALK performance (r range=0.42 to 0.51, p<0.01). Greater adiposity was associated with poorer 7-OB (r=0.43, p=0.004) and WALK (r=0.52, p<0.001) performance. Similarly, greater %Fat was associated with higher general fatigue (r=0.30, p=0.049) and mental fatigue (r=0.31, p=0.045) but not physical fatigue (p=0.43). STEPS were related to general fatigue (r=-0.32, p=0.04) but not physical or mental fatigue (p>0.05). Hierarchical multiple regression analyses were conducted to determine the independent contribution of %Fat and STEPS to 7-OB, WALK and general fatigue. Greater adiposity (b=0.32) and fewer STEPS (b=-0.31) were associated with poorer 7-OB (R2=0.27, p=0.002) and WALK performance (R2=0.37, p<0.001; b=-0.36 and 0.38, respectively). However, only %Fat (b=0.30) was an independent positive predictor of fatigue (p=0.049, R2=0.09). CONCLUSIONS: Physical function performance is influenced by adiposity and habitual physical activity; however, adiposity is the primary predictor of general fatigue in older women.