The relationship between body composition and physical performance in older women

BACKGROUND: The relationship between age-associated change in body composit ion and physical disability is still unknown. Skeletal muscle mass declines with age in both sexes; however, since women have less muscle mass per uni t of weight than men, these changes may be more debilitating in women. OBJECTIVE: To evaluate the relationship between body composition and physic al performance. DESIGN: A cross-sectional study. PARTICIPANTS: 144 women aged 68 to 75 were selected randomly from the gener al population of Verona. MEASUREMENTS: Body composition was evaluated using dual energy X-ray absorp tiometry and bioimpedance. Physical performance was evaluated using a modif ied version of the Activities of Daily Living scale. Distance walked in 6 m inutes was calculated, and isometric knee strength was tested. RESULTS: Normal women had a significantly lower body mass index (BMI) and p ercent body fat. These women also had a higher ratio of body cell mass (BCM ) and total fat free mass (FFM) than women with physical impairments. After adjusting for BMI, women in the lowest tertile of muscle strength had sign ificantly lower BCM than those in the highest tertile. CONCLUSIONS: These cross-sectional data show that although muscle strength is related to fat-free mass, disability in older women is associated with h eavier BMI and with a higher percentage of body fat.