Effects of exercise intensity and duration on nocturnal heart rate variability and sleep quality

Abstract

Acute physical exercise may affect cardiac autonomic modulation hours or even days during the recovery phase. Although sleep is an essential recovery period, the information on nocturnal autonomic modulation indicated by heart rate variability (HRV) after different exercises is mostly lacking. Therefore, this study investigated the effects of exercise intensity and duration on nocturnal HR, HRV, HR, and HRV-based relaxation, as well as on actigraphic and subjective sleep quality. Fourteen healthy male subjects (age 36 ± 4 years, maximal oxygen uptake 49 ± 4 ml/kg/min) performed five different running exercises on separate occasions starting at 6 p.m. with HR guidance at home. The effect of intensity was studied with 30 min of exercises at intensities corresponding to HR level at 45% (easy), 60% (moderate) and 75% (vigorous) of their maximal oxygen uptake. The effect of duration was studied with 30, 60, and 90 min of moderate exercises. Increased exercise intensity elevated nocturnal HR compared to control day (p < 0.001), but it did not affect nocturnal HRV. Nocturnal HR was greater after the day with 90- than 30- or 60-min exercises (p < 0.01) or control day (p < 0.001). Nocturnal HRV was lower after the 90-min exercise day compared to control day (p < 0.01). Neither exercise intensity nor duration had any impact on actigraphic or subjective sleep quality. The results suggest that increased exercise intensity and/or duration cause delayed recovery of nocturnal cardiac autonomic modulation, although long exercise duration was needed to induce changes in nocturnal HRV. Increased exercise intensity or duration does not seem to disrupt sleep quality.

Heart rate variability is related to training load variables in interval running exercises

“…We did not investigate the effects of increased exercise duration on nocturnal HRV, but based on the results during short-term recovery, probably no differences would have been noticed, since differences between exercises were quite small at the end of the 15 min controlled recovery. In contrary, in a recent study by Myllymäki et al (2012), exercise duration was increased from 30 minutes to 90 minutes at the intensity of 60 % vVO2max in moderately physically active male subjects, which is quite similar to exercise protocols of the recreationally trained subjects of the present study. They found increased nocturnal HR after 90 min exercise when compared to 30 or 60 min exercises, and decreased HRV after 90 min exercise when compared to a control day without exercise.…”

“…In previous studies, it has been shown that the effects of a high-intensity prolonged exercise on post-exercise HRV may be observed until the night following exercise or even longer (Hautala et al 2001;Hynynen et al 2010;Mourot et al 2004), either when compared to resting day (Hautala et al 2001) or some kind of control exercise Myllymäki et al 2012). In the study of Hynynen et al (2010), the intensity of the baseline exercise was increased, so the exact effects of the increased duration of exercise cannot be analyzed, but the results of the study indicated a long-lasting decrement of vagal activation after high-intensity endurance exercise.…”

Recovery of rescuers from a 24-h shift and its association with aerobic fitness

“…The following HRV parameters elicited from the data were analyzed: standard deviation of normal-to-normal intervals (SDNN), root mean square of successive differences (RMSSD), very low frequency power (VLF) (0.003-0.04 Hz), low frequency power (LFP) (0.04-0.15 Hz), high frequency power (HFP) (0.15-0.40 Hz), low to high frequency ratio (LF/HF), and total power (TP). The same software also computes stress and relaxation percentages for the recording period using the neural network modeling [21], and both of them were used in the later analysis.…”

Exercise and sleep - Review and future directions

“…No changes in HRV were found after three months of the aerobic training program. Recently, Myllymäki and colleagues published two papers focusing exclusively on cardiac autonomic function during sleep 36,37) . Their studies were designed to observe the acute effects of single bouts of exercise on later sleep.…”