Atividade física, comportamento sedentário e excesso de peso em idosos: um estudo longitudinal

Abstract

Aging is accompanied by biological, physiological and behavioral changes that can contribute to increased body weight and the risk of death in individuals with advanced age. Thus, it is necessary to verify the direct and indirect effects of sociodemographic, behavioral and health conditions on the body mass index (BMI) and the predictive ability of overweight on the risk of mortality. This is a longitudinal study, characterized as a prospective cohort with two waves, consisting of elderly residents in the urban area of Alcobaça – BA and registered in the Family Health Strategy. Baseline data collection was carried out from July to October 2015 (n=473) and follow-up, from January to February 2020 (n=222). A questionnaire was applied containing sociodemographic, behavioral and health information. In addition, an anthropometric assessment was performed. Descriptive statistical analysis, McNemar's Chi-Square, Structural Equation Modeling and Cox Regression were applied, considering p<0.05. In Structural Equation Modeling, the final model showed good quality of fit (x²(gl=62)=71,0; p=0,204; CFI=0,97; GFI=0,96; TLI=0,96; RMSEA=0,03). Direct associations were found between younger age (p<0.001), higher monthly income (p=0.001), greater functional disability for IADL (p=0.02) and greater number of morbidities (p<0.001) with the highest BMI value. It was observed that higher education level (β=0.07) and male gender (β=-0.02), mediated by the higher monthly income, were indirectly associated with the higher total BMI value, such as the shorter MVPA time (β=-0.02) and less education (β=-0.05), mediated by greater functional disability for IADL. Furthermore, the female gender, mediated by the greater number of morbidities (β=0.05), greater functional disability for instrumental activities of daily living (IADL) (β=-0.02) and lower monthly income (β=- 0.02), was indirectly associated the highest total BMI value among the elderly. In the adjusted survival analysis, excess weight was a protective factor for the risk of mortality (HR 0.54; CI 0.30–0.97; p=0.040). Thus, overweight elderly people had 46.0% lower risk of mortality when compared to those who did not have this condition. The results of this study show the importance of conducting new research using methods of assessing body composition that enable the distinction between fat and lean mass. In addition, comparative analyzes based on multicenter studies are essential to verify which cutoff point of the BMI best predicts overweight and mortality in the elderly. The need to evaluate the impact of nutritional status on the health of the elderly is highlighted, considering different age groups, since in younger elderly people, excess weight seems to have a negative impact on health, whereas the higher BMI in long-lived elderly could be present as a protective factor. In addition, it is suggested to carry out interventions that stimulate the improvement of lifestyle by increasing the intensity and duration of physical activity including those activities of light intensity, associated with a reduction in the time of exposure to sedentary behavior, aiming at reducing possible deleterious health effects related to changes in nutritional status in older individuals.