Associação independente, estratificada e conjunta entre atividade física e comportamento sedentário com desfechos cardiovasculares em adultos e idosos

Abstract

Cardiovascular diseases are the leading cause of death in Brazil, representing a major public health challenge. Monitoring and controlling risk factors such as hypertension, obesity, elevated anthropometric indicators (e.g., waist circumference), and cardiometabolic scores are essential to prevent their progression. Among the modifiable factors, physical activity (PA) and sedentary time (ST) stand out, as regular PA contributes to heart health, while prolonged sedentary behavior may increase cardiovascular risk. In this context, this thesis investigated the association between PA, ST, and cardiovascular outcomes in adults and older adults, and is composed of three scientific articles. The first, a systematic review, examined the methodological approaches and main findings on the independent, stratified, and joint associations between ST, PA, and cardiovascular outcomes. The results indicated that ST was positively associated, and PA was inversely associated with the outcomes. Moreover, a stronger impact of ST was observed in individuals with low PA, whereas higher levels of PA attenuated—but did not eliminate—its negative effects. The joint analysis indicated a higher cardiovascular risk in individuals with high ST and low PA, as well as elevated risk in intermediate combinations. The second article analyzed the independent, stratified, and joint associations between PA, ST, and cardiovascular risk factors, including blood pressure, body composition, and cardiometabolic health. Data were drawn from the 1982 Pelotas Birth Cohort, specifically from the 30- and 40-year follow-ups. Physical activity was measured by accelerometry and questionnaire, while sedentary behavior was assessed by accelerometry. The results showed that the associations were inconsistent or nonexistent across the different analyses. Indeed, there is a complex relationship between physical activity, sedentary behavior, and cardiovascular outcomes. Finally, the third article investigated these independent, stratified, and joint associations between PA and ST with major adverse cardiovascular events (MACEs) in a cohort of older adults. The "Como vai?" cohort began as a population-based study in 2014, and MACEs were assessed 2.6 years after baseline, including all-cause mortality, heart failure, and ischemia. The independent analysis showed that ST was not associated with MACEs after adjustment for moderate-to-vigorous physical activity (MVPA). However, individuals in the highest tertile of MVPA had a lower risk of MACEs, even after adjusting for ST and history of non-fatal MACEs. Stratified and joint analyses of ST and MVPA with MACEs were not statistically significant. These findings reinforce the importance of PA in reducing cardiovascular risk and suggest that the impact of ST may depend on PA levels.