Metaboreflex Activation Delays Heart Rate Recovery after Aerobic Exercise

Abstract

The role of metaboreflex on heart rate recovery after exercise (HRR) is controversial. It is speculated that this mechanism is active in exercises with larger muscle masses, however it has not been tested after a typical aerobic exercise. The aim of this study was to evaluate the influence of metaboreflex on HRR. 12 healthy middle‐aged men randomly underwent 2 sessions consisting of an exercise (cycle ergometer, 70% VO2peak, 30 min) followed by 5 min of recovery. In each session, the recovery was performed with (occlusion) or without (control) leg circulatory occlusion (cuffs at the hips inflated to supra‐systolic pressure). ECG was registered and HRR was assessed by: heart rate reduction after 60 (HRR60s) and 300s (HRR300s) of recovery; short‐term time constant of HRR (T30); time constant of the HRR after exponential fitting (HRRτ); and mean values of HR in segments of 30s (HR30s). Heart rate variability (HRV) was assessed by the root mean square residual (RMS) and square root of mean squared differences of successive R–R intervals (rMSSD) on subsequent 30‐s segments. Paired T‐test, Wilcoxon test and ANOVA were employed. HRR60s (25 ± 7 vs. 22 ± 12 beats.min‐1, p = 0.69), T30 (284 ± 155 vs. 309 ± 253 s, p = 0.89) and HRRτ (120 ± 45 vs. 107 ± 103 s, p = 0.75) were similar between control and occlusion sessions, respectively. HRR300s was significantly lower in occlusion session (30 ± 13 vs. 38 ± 14, p = 0.05). There was no session vs. time interaction for the rMSSD index (p = 0.46), while HR30s and RMS had significant time vs. session interactions (p = 0.00 and 0.01, respectively), showing slower decrease of HR30s and slower increase of RMS in the occlusion session. In conclusion, metaboreflex activation delays HRR, particularly at the slower phase of HRR.Funding: FAPESP 2013/044997‐0 and 2013/05519‐4; CAPES PROEX