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

Abstract

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 (VO2Peak) and the speed associated with VO2Peak (sVO2Peak), the subjects completed 2 random experimental trials: high-intensity exercise (HIE - 1:1 at 100% sVO2Peak), and moderate-intensity continuous exercise (MIE - 70% sVO2Peak). 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<0.05, respectively). A group effect was also found for LFlog (F=23.91, p<0.05), and HFlog (F=57.55, p< 0.05). LF/HF returned to resting value 15 min after MIE exercise and 20 min after HIE exercise. This means that the heavy domain (aerobic and anaerobic threshold) induces dissimilar autonomic modification in physically active subjects. Both HIE and MIE modify HRV, and generally HIE delays parasympathetic autonomic modulation recovery after iso-volume exercise.

High-Intensity Intermittent Exercise and Autonomic Modulation: Effects of Different Volume Sessions

“…This is supported by the group effect between HIIE recovery was delayed for 25 and 30 min after HIIE 1.25 and HIIE 2.5 , respectively. On the other hand, Cabral-Santos et al [8] observed that LF-log returned to rest level after 20 min of recovery after a 5-km HIIE, whereas HF-log remained elevated for 35 min. The results observed in the present study show that the volume of high-intensity exercise training protocols also affect HRV recovery.…”

“…During recovery, HRV is kept low for a few minutes according to exercise intensity, duration, and mode [9,25,33]. HRV recovery is widely used to determine acute stress response to different modes of exercise in both trained and untrained individuals [4,8,33]. This information is relevant for exercise prescription, and because HIIE has become widely used for different populations, understanding the stress responses of the autonomic nervous system after HIIE of similar intensities but different volumes is important.…”

“…Different studies have proposed to investigate HRV recovery after exercises with different intensity and volume [12,20,21], similar volumes [8], and similar energy expenditure [31] among trained or physically active subjects [8,33,30]. These studies have shown that higher exercise intensity leads to slower HRV recovery among physically active subjects, which is an important finding for exercise prescription.…”

“…Our group recently found that 5 kilometers (km) of high-intensity intermittent exercise (HIIE) delays HRV recovery (during 60 min of recovery, root mean square of successive differences [RMSSD] stayed lower) when compared to a session of moderate-intensity exercise with the same volume [8]. When compared to moderate intensity, HIIE seems to be more efficient to improve body composition and physical fitness [5,6,15]; in addition, subjects reach their goals faster with HIIE when compared to moderate-intensity exercise (time efficiency).…”

Influência Da Atividade Física Na Modulação Autonômica Cardíaca

“…With this, researches show that regular practice of physical activity leads the individual to have a more pronounced HR recovery when comparing the same indexes in the weeks before sedentary people beginning the practice. In this way, there is a greater physical resistance, decreasing the ability to overload the heart in other activities 21,22 .…”