Efeitos do treinamento físico sobre as respostas cardiovasculares à ativação metaborreflexa muscular em pacientes com doença arterial coronariana

Abstract

Background: Patients with coronary artery disease (CAD) may present abnormalities in the muscle metaboreflex that can result in exercise intolerance and increased cardiovascular risk. Adaptations to the muscle metaboreflex to physical training in these patients have not yet been investigated. Aim: To investigate the cardiovascular responses to activation of the muscle metaboreflex in patients with CAD and the effects of a supervised multimodal physical training program on these responses. Methods: Patients with CAD (CAD group; n = 11; 60.5 ± 8.3 y) were compared with control volunteers without evidence of CAD (CONT group, n = 9; 54.7 ± 6.3 y) regarding cardiovascular responses at rest and during a cold pressor test (CPT) and muscle metaboreflex activation with and without topical capsaicin application, using a post-exercise circulatory arrest (PECA) protocol. Heart rate (HR) and blood pressure (BP) were assessed beat-to-beat by a cardiomonitor and digital infrared photoplethysmography, respectively. Using the Modelflow method, stroke volume (SV), cardiac output (CO), and systemic vascular resistance (SVR) were calculated. Lactate levels were assessed at rest and after PECA using a lactate analyzer. After these comparisons (CAD vs. CONT), the CAD group was reevaluated after 12 weeks of participation in a supervised multimodal physical training program consisting of 2-3 weekly sessions lasting 60 minutes each. Results: During the CPT, the CAD group showed a more pronounced increase in mean arterial pressure [MAP] (38.0 ± 9.0 vs. 18.7 ± 16.8 mmHg; p < 0.01) and SVR (1053.0 ± 600.5 vs. 499.8 ± 481.0 dyn.sec.cm-5; p = 0.04) compared to the CONT group, while the increase in HR was higher in the CONT group (17.5 ± 9.0 vs. 8.1 ± 5.0 bpm; p = 0.01). Muscle metaboreflex activation resulted in greater changes from rest in CAD compared to CONT in systolic blood pressure [SBP] (27.5 ± 17.3 vs. 14.2 ± 4.5 mmHg; p = 0.04), diastolic blood pressure [DBP] (10.1 ± 6.5 vs. 4.2 ± 1.8 mmHg; p = 0.02), MAP (27.5 ± 17.3 vs. 14.2 ± 4.5 mmHg; p = 0.04), SVR (149.7 ± 86.9 vs. 61.0 ± 47.4 dyn.sec.cm-5; p = 0.02), and blood lactate (0.48 ± 0.42 vs. -0.18 ± 0.40 mmol/L; p < 0.01). After physical training, the CPT induced a smaller increase in DBP (24.33 ± 8.4 vs. 34.85 ± 12.94 mmHg; p = 0.05). Changes from rest induced by muscle metaboreflex in the CAD group decreased by 28% (p = 0.05), 28% (p = 0.04), and 85% (p = 0.01) for DBP, MAP, and blood lactate, respectively. No significant differences were found for SV and CO, as well as for capsaicin application in the investigated variables for any of the comparisons (CAD vs. CONT or pre- vs. post-training in CAD). Conclusion: The pressor response to muscle metaboreflex activation is exacerbated in patients with CAD, partly due to exaggerated increases in SVR and blood lactate levels. The efferent pathway of the muscle metaboreflex appears to be involved in these alterations. However, physical training attenuated these responses