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Abstract
In older women, physical function (PF) is impacted by physical activity (PA), adiposity (%Fat), muscle power, and muscle quality (MQ). The aim of this study was to assess the influences of PA, %Fat, leg power, MQ [lower body power (watts) / lower body lean mass (kg)], on perceived and performance-based PF in older women varying in functional status. Women (n = 97; age = 73.8 5.6 years) were assessed for habitual PA via the CHAMPS questionnaire, body composition via DXA, and leg power via the Nottingham power rig. Lower extremity physical function (LEPF) was evaluated using Physical Performance Test (PPT), 30 second chair rise (CHR), 8 foot up and go (UpGo), and 6 minute walk test (6MWT). Perceived PF was determined using the SF-36 Physical Function scale. PA (total caloric expenditure per week) was not related to MQ or %Fat. MQ and %Fat were significantly related to LEPF [PPT, UpGo, CHR; r = 0.43 to -0.48 and 0.35 to -0.39, respectively (all p < 0.05)]. Tertiled by MQ, MQ was associated with PPT scores in a sequential manner such that greater MQ was associated with greater PPT scores; however, %Fat tertiles were not related to PPT (p > 0.05). Perceived PF and performance-based PF (PPT, UpGo, CHR, and 6MWT) were related (r range -0.41 to 0.52, all p < 0.01). Perceived PF was also associated with %Fat, MQ, and PA (r = -0.31, 0.26, 0.28, respectively, all p < 0.05). Regression analyses revealed that age, medical conditions, PA, %Fat, and MQ independently contributed to perceived PF, explaining 38% of the total variance; however, MQ and PA (moderate MET-Hours) were the only significant independent predictors of performance-based PF explaining 31% of the variance. The findings suggest that MQ and %Fat are associated with LEPF in older women. Perceived PF is associated with performance-based PF, and physiological and behavioral variables, including %Fat, MQ, and PA, may influence perceptions of PF in older women. Future research should utilize an approach which integrates psycho-social, muscle capacity and behavioral outcomes to develop the most effective strategies to enhance PF in older women.