Association between the fat mass/fat-free mass ratio and muscle strength, static balance and exercise capacity in older adults: a cross-sectional study.

Background: the FM/FFM ratio has been proposed as a new body composition variable. However, the association between FM/FFM ratio and physical function in older adults remains limited. Therefore, the aim of this study was to analyze the association between FM/FFM ratio and muscle strength, static balance, and exercise capacity in older adults. Methods: this was a cross-sectional study involving 392 older adults from Londrina, Brazil. Subjects underwent body composition analysis by bioelectrical impedance, and assessments for aerobic capacity, muscle strength and static balance including the 6-minutes walking test, handgrip strength and one-legged stance test. Statistical analysis was conducted using correlation tests and lineal regression models adjusted for age and gender. The statistical significance considered was p < 0.05. Results: a total of 392 older adults participated (mean age = 69.77 years; women: 74.7 %). The FM/FFM ratio was significantly associated with muscle strength (β = -22.779, 95 % CI: -26.741 to -18.818; p < 0.001), static balance (β = -14.335, 95 % CI: -19.980 to -8.690; p < 0.001), and exercise capacity (β =-98.937, 95 % CI: -152.286 to -45.588, p < 0.001). After adjusting for age and gender, FM/FFM ratio was an important predictor of muscle strength (β = -4.687, 95 % CI: -8.646 to -0.728; p = 0.020) and static balance (β = -18.361, 95 % CI: -24.943 to -11.778; p < 0.001). Conclusions: the FM/FFM ratio is an important clinical measure of body composition that is significantly associated with key indicators of physical performance, including muscle strength, static balance, and exercise capacity in older adults.