Metabolic And Cardiovascular Responses To Muscle Metaboreflex Activation In Patients With Coronary Artery Disease

Patients with coronary artery disease (CAD) often exhibit higher pressor responses to acute exercise. Cardiovascular adjustments during exercise are managed by neural mechanisms, including the muscle metaboreflex. Altered skeletal muscle reflexes may lead to exercise intolerance or a higher cardiovascular risk. Investigating the role of exercise training on the muscle metaboreflex in this population is crucial. PURPOSE: To investigate the cardiometabolic responses to muscle metaboreflex activation in CAD patients vs. healthy controls, as well as the exercise-induced changes in these responses. METHODS: At baseline, 11 patients with CAD (CAD: 60.5 ± 8.2 y; 29.2 ± 2.8 kg.m-2) and 7 healthy controls (CTL: 56.0 ± 6.3 y; 24.3 ± 3.2 kg.m-2) were evaluated at rest and during metaboreflex activation, which consisted of 90 s of isometric handgrip exercise at 40% of maximal voluntary contraction followed by 3 min of post-exercise circulatory arrest (PECA). Metaboreflex responses were assessed by calculating delta changes (PECA minus rest) for mean arterial pressure (MAP), cardiac output (CO), stroke volume (SV), systemic vascular resistance (SVR) and blood lactate concentration. Patients with CAD were reevaluated after 12 weeks of supervised multimodal exercise training with moderate intensity (2 to 3 times/week and 1 hour/session). RESULTS: At baseline, the CAD group showed a higher muscle metaboreflex response for MAP (17.3 ± 10.7 vs. 8.2 ± 3.1 mmHg; p = 0.04) and SVR (0.14 ± 0.08 vs. 0.05 ± 0.05 PRU; p = 0.03) than the CTL group. No significant differences were found between groups for SV (CAD: 2.16 ± 5.23 vs. CTL: 6.61 ± 5.85 mL; p = 0.12), CO (CAD: 0.15 ± 0.24 vs. CTL: 0.19 ± 0.42 L.min-1; p = 0.78) and blood lactate (CAD: 0.48 ± 0.42 vs. CTL: 0.08 ± 1.05 mmol.L-1; p = 0.06). After exercise training, muscle metaboreflex responses in CAD group for MAP, SVR and blood lactate decreased by 29% (p = 0.03 vs. baseline), 39% (p = 0.11 vs. baseline) and 83% (p = 0.01 vs. baseline), while SV and CO increased by 50% (p = 0.74 vs. baseline) and 180% (p = 0.44 vs. baseline); respectively. CONCLUSIONS: Pressor responses during muscle metaboreceptor stimulation are increased in patients with CAD, partly due to exaggerated vasoconstriction. Exercise training restores MAP and blood lactate responses to muscle metaboreflex activation in these patients. This study was financed in part by the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (E-26/200.132/2023) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001.