Association between body composition, localized muscle fatigue of the lower limbs and functional autonomy in old age

Abstract

Introduction: The analysis of the proportion elderly/children shows that the elderly population is growing faster than the population of children. Due to the gradual decline in the rate of infant mortality and fertility, life expectancy becomes increased, contributing to the aging of the population. This fact leads to an important worry about the quality of life that older people will have in the future, because aging is associated to important morphological and functional changes. The reduction in muscle mass and the increase in body fat are typical of aging. The decline of strength and resistance to fatigue may lead the elderly to decreased functional autonomy. Objective: This study aimed to verify the existence of a relationship among body composition, muscle strength, fatigue of the lower limbs and functional autonomy in active elderly. Methods: The sample consisted of 29 elderly women with a mean age of 68.2 (± 7.3) years. We analysed body composition by total and segmental bioelectrical impedance and muscle fatigue using surface electromyography (by the values of median frequency and root mean square in a one-minute test to 50% of maximum voluntary isometric contraction). Functional autonomy was assessed by the Group of Latin American Development to Maturity (GDLAM) protocol. The Pearson correlation coefficient was used for data analysis, in SPSS software, version 13.0 (p < 0.05) Results: There were significant correlations between height and strength (r = 0.49; p= 0.007), age and lean mass (r = -0.42; p= 0.027), fat percentage (% F) and GDLAM tests (r 0.39 to 0.41; p 0.020 to 0.049). Lean mass was positively correlated with strength (r = 0.55; p = 0.003) but not with the resistance to fatigue. Conclusion: The evaluated elderly with greater fat free mass were associated with better performance in the maximum force, but not in the resistance to fatigue test, suggesting that these two parameters (strength and fatigue) are independent. The elderly with high %F showed worse performance in GDLAM, showing that older adults with higher levels of body fat have higher functional limitations related to autonomy.