Impact of High-intensity Intermittent and Moderate-intensity Continuous Exercise on Autonomic Modulation in Young Men.

The aim of this study was to compare heart rate variability (HRV) recovery after two iso-volume (5 km) exercises performed at different intensities. 14 subjects volunteered (25.17±5.08 years; 74.7±6.28 kg; 175±0.05 cm; 59.56±5.15 mL·kg −1 ·min −1 ) and after determination of peak oxygen uptake (VO 2Peak ) and the speed associated with VO 2Peak (sVO 2Peak ), the subjects completed 2 random experimental trials: high-intensity exercise (HIE – 1:1 at 100% sVO 2Peak ), and moderate-intensity continuous exercise (MIE – 70% sVO 2Peak ). HRV and RR intervals were monitored before, during and after the exercise sessions together with, the HRV analysis in the frequency domains (high-frequency – HF: 0.15 to 0.4 Hz and low-frequency – LF: 0.04 to 0.15 Hz components) and the ratio between them (LF/HF). Statistical analysis comparisons between moments and between HIE and MIE were performed using a mixed model. Both exercise sessions modified LFlog, HFlog, and LF/HF (F=16.54, F=19.32 and F=5.17, p