High‐intensity interval training decreases muscle sympathetic nerve activity and improves peripheral vascular function in patients with heart failure with reduced ejection fraction

Abstract

BackgroundModerate intensity continuous exercise (MICT) has been shown to reduce muscle sympathetic nerve activity (MSNA) in heart failure patients with reduced ejection fraction (HFrEF). However, the effects of high‐intensity interval training (HIIT) on MSNA in HFrEF patients are unknown. We hypothesized that reductions in MSNA would be greater following HIIT than MICT and correspond with improvements in peripheral vascular function.MethodsHFrEF patients (30 ‐ 65 years), left ventricular ejection fraction ≤ 40%, Functional Classes II–III, were randomized into HIIT, MICT or no training (NT) three times/week for 12 weeks. MSNA was assessed by microneurography. Brachial artery flow‐mediated dilation (FMD), blood flow and vascular conductance were assessed by ultrasonography, blood pressure (BP) and heart rate (HR) by plethysmography and peak oxygen uptake (V̇O2peak) by a cardiopulmonary exercise test.ResultsBoth, HIIT and MICT, led to reductions in MSNA (frequency and incidence burst) relative to NT (p<0.05). However, the reduction in MSNA was more pronounced following HIIT than MICT (p<0.05). Increases in brachial artery FMD, resting blood flow and conductance were also greater following HIIT than MICT (p<0.05), while V̇O2peak increased similarly following HIIT and MICT relative to NT. No changes in BP or HR were observed in either exercise condition. Further analysis showed a negative correlation between changes in MSNA and FMD following the interventions (r=−0.60, p=0.005).ConclusionOur findings indicate that 12 weeks of HIIT is superior to MICT in reducing sympathetic overactivity and improving vascular function in patients with HFrEF, despite similar increases in exercise capacity.Support or Funding InformationFAPESP Grants (2014/11671‐6 and 2017/25613‐6)