INDEPENDENT AND COMBINED ASSOCIATIONS OF CARDIORESPIRATORY FITNESS AND LOWER LIMB MUSCLE STRENGTH WITH THE RISK AND OCCURRENCE OF MAJOR ADVERSE CARDIOVASCULAR EVENTS IN OLDER ADULTS
Aging, physical function, cardiometabolic risk, cardiovascular diseases.
Objectives: This thesis investigated the independent and combined associations of cardiorespiratory fitness (CRF) and muscle strength (MS) with cardiometabolic and cardiovascular outcomes in older adults aged 60 to 80 years.
Methods: CRF was assessed using the six-minute walk test, and MS was evaluated using the 30-second chair stand test. Cardiometabolic outcomes were determined by the presence of metabolic syndrome and ideal cardiovascular health score, both defined according to the American Heart Association. Cardiovascular outcomes, termed major adverse cardiovascular events (MACE), included myocardial infarction, coronary artery disease, cardiac surgery, heart failure, stroke, and all-cause mortality.
Results: The first study (n = 360), a cross-sectional analysis, showed that low levels of CRF, independently and in combination with low MS, were associated with increased cardiometabolic risk, reflected by a higher prevalence of metabolic syndrome (PR 1.27, 95% CI 1.09–1.48; and PR 1.32, 95% CI 1.10–1.58, respectively) and poor cardiovascular risk score (PR 1.76, 95% CI 1.25–2.47; and PR 1.65, 95% CI 1.19–2.28, respectively). The second study (n = 234), a longitudinal analysis with an average follow-up of five years, investigated the association of these physical capacities with the occurrence of MACE (n = 30). Results showed that low CRF was independently associated with a higher risk of MACE (HR 2.56; 95% CI: 1.05–6.24), even after adjusting for MS and clinical covariates. Moreover, the combination of low CRF and low MS conferred the highest risk for such events (HR 3.58; 95% CI: 1.32–9.69), reinforcing the predictive value of jointly assessing these variables in clinical settings. Additive and multiplicative interaction analyses indicated a trend toward interaction (p = 0.085), although not statistically significant.
Conclusions: Overall, the findings of this thesis support that a multidimensional assessment of physical fitness, especially the combination of CRF and MS, may enhance cardiovascular risk stratification in older adults, with relevant implications for prevention and clinical management in this population.