Exercise Training Restores Muscle Mechano and Metaboreflex Sensitivity in Heart Failure Patients

Abstract

Increased sympathetic muscle mechanoreflex sensitivity and attenuated sympathetic muscle metaboreflex sensitivity have been described in heart failure (HF) patients. We tested the hypothesis that exercise training (ET) would improve sympathetic mechano and metaboreflex sensitivity in HF patients. 24 consecutive, randomized, HF patients, Functional Class II-III NYHA, EF≤40% were divided into two groups: Exercise-trained (n=12, 55±2 years) and untrained (n=12, 54±2 years). 10 normal controls (NC) were also studied. Muscle sympathetic nerve activity (MSNA) was directly recorded from the peroneal nerve. Mechanoreceptors were activated by passive exercise. Metaboreceptors were activated by post-exercise circulatory arrest. ET consisted of three 60-minutes exercise sessions per week for 4 months. ET significantly reduced MSNA in HF patients (34 vs. 40 bursts/min, P<0.05). ET significantly reduced MSNA responses to passive exercise ({Delta} = 2 vs. 5 bursts/min, P<0.05) and increased MNSA responses during post-exercise circulatory arrest ({Delta} = 5 vs. –1 bursts/min, P<0.0 5). These changes were so dramatic that the difference between HF patients and NC were no longer observed. No changes in untrained HF patients were found. In conclusion, ET restores sympathetic muscle mechano and metaboreflex sensitivity in HF patients, which may contribute to the reduction in MSNA and clinical outcomes in these patients.