Relação entre composição corporal, baixa massa muscular e desempenho físico em mulheres de meia-idade e idosos: um estudo transversal

Abstract

Background: Among the clinically significant changes that occur during female aging, it is highlighted those that alter body composition and leads to decrease in muscle mass and bone density, as well as increase in fat mass, with changes in body fat distribution pattern. These changes cause significant impacts on the musculoskeletal system, with reduction of the muscle strength, impairments on physical performance, functional capacity and health of women from middle age. Objective: To analyze the relationship between body composition, low muscle mass and physical functional performance in middle-aged and elderly women living in the community. Methods: This is an observational, analytical and cross-sectional study with an epidemiological nature. The population consisted of women aged 40 to 80 years, residing in Parnamirim and Santa Cruz, state of Rio Grande do Norte, Brazil. The source sample of the study was composed of 708 women. Then, for eavh study performed, a target sample was used, with 593 women in first artivle and 368 women in the second. The data collection consist of biochemical dosage, body composition and physical performance evaluations. In addition, sociodemographic and socioeconomic data and regular practice of physical activity were also collected. For statistical analysis, measures of central tendency and dispersion, Student's t-test, ROC curve, chi-square, logistic regression, Pearson correlation and canonical correlation were used. The dependent variables of the study were low muscle mass, handgrip strength, walking speed, sitting and standing test and total Short Physical Performance Battery (SPPB) score. The group of independent variables were composed by adiposity anthropometric indices: BMI (body mass index), WC (waist circumference), WHR (waist-hip ratio), RCA (waist-height ratio), CI (taper index), BAI (body adiposity index), VAI (visceral adiposity index) and LAP (lipid accumulation product). Results: The results of this thesis created two scientic articles. Regarding the results of the first article, it was observed that the adiposity anthropometric indices cut-off points were able to identify the presence of low muscle (p <0.05), except for VAI only. After regression analysis, the CC, WHR, RCA and BAI indices were associated with a higher risk of low muscle mass (6.2; 1.8; 5.0 and 14.5 respectively). Regarding the second article, the first three canonical functions were statistically significant. These accounted for 97.54% of the shared variance between the two sets of variables. However, the first function presented the best estimate of the shared variance. Moreover, it presented the highest canonical correlation and the highest redundancy index (percentage cumulative variance = 82.52, Wilks Lambda = 0.66, canonical correlation = 0.532, p value <0.001). From the analysis of the first canonical function, an inverse correlation was observed between the CI (-0.59) and handgrip strength (0.84) and SPPB (0.68), besides direct correlation with walking speed (- 0.43). Conclusions: Changes in body composition during women aging are related to decreasing of muscle mass and physical performance in middle-aged and elderly women. The cut-off points of the adiposity anthropometric indices created are effective in identifying low muscle mass. This shows that the increasing of these indices would increase the chance of present low muscle mass. Moreover, it was observed that physical performance is influenced by changes in body composition that occur with the rise in age. The results presented important clinical relevance. A better understanding of this theme is fundamental to provide scientific support for the planning of public health policies.