Metaboreflex activation delays heart rate recovery after aerobic exercise in never-treated hypertensive men

Abstract

Muscle metaboreflex influences heart rate (HR) regulation after aerobic exercise. Therefore, increased metaboreflex sensitivity may help to explain the delayed HR recovery (HRR) reported in hypertension. This study assessed and compared the effect of metaboreflex activation after exercise on HRR, cardiac baroreflex sensitivity (cBRS) and heart rate variability (HRV) in normotensive (NT) and hypertensive (HT) men. Twenty-three never-treated HT and 25 NT men randomly underwent two-cycle ergometer exercise sessions (30min, 70%VO_2peak) followed by 5 min of inactive recovery performed with (occlusion) or without (control) leg circulatory occlusion (calf cuff inflated to a suprasystolic pressure). HRR was assessed via HR reduction after 30, 60 and 300s of recovery (HRR30s, HRR60s and HRR300s), and by the analysis of short- (T30) and long-term (HRRt) time constants of HRR. cBRS was assessed by sequence technique and HRV by the root mean square residual (RMS) and the root mean square of successive differences between adjacent RR intervals (RMSSD) on subsequent 30s segments. Data were analysed using two- and three-way ANOVAs. HRR60s and cBRS were significant and similarly reduced in both groups in the occlusion compared with the control session (combined values: 20 ± 10 vs. 26 ± 9 bpm and 2.1 ± 1.2 vs. 3.2 ± 2.4 ms mmHg⁻¹, respectively, P < 0.05). HRR300s and HRV were also reduced in the occlusion session, but these reductions were significantly greater in HT compared to NT (−16 ± 11 vs. −8 ± 15 bpm for HRR300s, P < 0.05). The results support the role of metaboreflex on HRR and suggest that increased metaboreflex sensitivity may partially explain the delayed HRR observed in HT men.

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