Estilo de vida, composição corporal e risco cardiovascular : relação com a aptidão cardiorrespiratória em trabalhadores rurais do interior do Rio Grande do Sul.

Abstract

Introduction: In rural populations, low socioeconomic status, limited access to healthcare services, and physical inactivity during leisure time can negatively affect cardiorespiratory fitness (CRF), thereby increasing cardiovascular risk. High levels of CRF may exert a protective effect among rural workers. General Objective of the Dissertation: To analyze lifestyle, body composition, and cardiovascular risk among workers with different levels of CRF. Manuscript I. Objective: To characterize the socioeconomic, occupational, and health conditions, as well as the presence of cardiovascular risk factors among rural workers from the interior of Rio Grande do Sul (RS), Brazil. Methods: A cross-sectional, descriptive study was conducted with rural workers from municipalities that are part of the Regional Development Council of Vale do Rio Pardo, RS. Socioeconomic and lifestyle data were collected using a questionnaire; systolic and diastolic blood pressure were measured using a manual sphygmomanometer; body mass index was calculated (kg/m²); blood glucose, total cholesterol, and triglyceride levels were measured via biochemical tests; cardiovascular risk was assessed using the Framingham Risk Score (FRS); and CRF was estimated following a treadmill test based on the Modified Bruce Protocol. Results: A total of 99 rural workers participated, 54.0% of whom were male, 63.6% were over 51 years old, 65.5% had not completed elementary education, and 77.7% belonged to socioeconomic class “C.” Women spent more hours on domestic work. Physical inactivity during leisure time (69.7%), overweight (42.3%), elevated total cholesterol levels (66.7%), and systolic hypertension (58.6%) were prevalent. Furthermore, 22.2% of participants had “good” CRF, and 41.8% were classified as having intermediate cardiovascular risk. Conclusion: The rural workers studied presented several cardiovascular risk factors, including physical inactivity, overweight, systolic hypertension, and elevated total cholesterol levels, with over one-third exhibiting intermediate cardiovascular risk. Manuscript II: Objective: To analyze the association between lifestyle, work conditions, and cardiovascular risk among rural workers with adequate and inadequate CRF. Methods: A cross-sectional, analytical study was conducted with 99 rural workers, who were divided into two groups according to their CRF levels. Socioeconomic and lifestyle data were collected via questionnaire; biochemical tests measured total cholesterol, triglycerides, and fasting glucose; systolic and diastolic blood pressure were measured with a manual sphygmomanometer; cardiovascular risk was assessed using the Framingham Risk Score; and CRF was estimated following the Modified Bruce Protocol. Chi square tests were applied for group comparisons. Results: Significant differences were found between groups regarding age, hours of sleep, working hours, and systolic and diastolic blood pressure (p < 0.05). CRF showed a weak positive correlation with daily working hours (R = 0.357), and weak negative correlations with systolic blood pressure (R = -0.283), diastolic blood pressure (R = -0.202), and cardiovascular risk percentage (R = -0.224). Conclusion: Inadequate CRF was more prevalent among older rural workers and those with fewer hours of sleep, compared to those with adequate CRF. Higher CRF levels were associated with lower systolic and diastolic blood pressure and reduced cardiovascular risk. Additionally, rural workers with longer working hours demonstrated higher CRF levels. Manuscript III: Objective: To analyze the influence of skeletal muscle mass (SMM) and visceral fat area (VFA) on the CRF of rural workers from the interior of Rio Grande do Sul, Brazil. Methods: A cross-sectional, analytical study involving 99 rural workers was conducted. Socioeconomic data were collected using a questionnaire. SMM and VFA were assessed using bioelectrical impedance analysis. CRF was estimated using predictive equations following a treadmill test based on the Modified Bruce Protocol. A multiple regression model was developed to estimate CRF (L·min⁻¹), including age, sex, SMM, and VFA as independent variables. Results: The model explained 45.2% of the variance in CRF data. Age (β = -0.012; p < 0.001; CI: -3.823, -0.481) was statistically significant, indicating that CRF decreases with increasing age. Similarly, SMM (β = 0.846; p = 0.001; CI: 0.346, 1.345) was statistically significant, showing that higher SMM is associated with better CRF. Conclusion: There is an inverse association between age and CRF, with CRF declining as age increases. Additionally, an association between CRF and SMM was observed, suggesting that greater skeletal muscle mass contributes to improved CRF.