Consciously Controlled Breathing Decreases the High-Frequency Component of Heart Rate Variability by Inhibiting Cardiac Parasympathetic Nerve Activity

Abstract

Heart rate variability (HRV), the beat-to-beat alterations in heart rate, comprises sympathetic and parasympathetic nerve activities of the heart. HRV analysis is used to quantify cardiac autonomic regulation. Since respiration could be a confounding factor in HRV evaluation, some studies recommend consciously controlled breathing to standardize the method. However, it remains unclear whether controlled breathing affects HRV measurement. We compared the effects of controlled breathing on HRV with those of spontaneous breathing. In 20 healthy volunteers, we measured respiratory frequency (f), tidal volume, and blood pressure (BP) and recorded electrocardiograms during spontaneous breathing (14.8 ± 0.7 breaths/min) and controlled breathing at 15 (0.25 Hz) and 6 (0.10 Hz) breaths/min. Compared to spontaneous breathing, controlled breathing at 0.25 Hz showed a higher heart rate and a lower highfrequency (HF) component, an index of parasympathetic nerve activity, although the f was the same. During controlled breathing at 0.10 Hz, the ratio of the low frequency (LF) to HF components (LF/HF), an index of sympathetic nerve activity, increased greatly and HF decreased, while heart rate and BP remained almost unchanged. Thus, controlled breathing at 0.25 Hz, which requires mental concentration, might inhibit parasympathetic nerve activity. During controlled breathing at 0.10 Hz, LF/HF increases because some HF subcomponents are synchronized with f and probably move into the LF band. This increment leads to misinterpretation of the true autonomic nervous regulation. We recommend that the respiratory pattern of participants should be evaluated before spectral HRV analysis to correctly understand changes in autonomic nervous regulation.

Effects of Hypoxia on Heart Rate Variability in Healthy Individuals: A Systematic Review

“…8,11,20,[22][23][24][25][26] The length of stay and type of rise to a simulated altitude could generate different cardiac autonomic modulation responses, as shown in the table 1. 12,27,28 Likewise, the different levels of oxygen used in the studies, ranging from 19% to 9.6% of FiO 2 10,21,23 also appear to induce different HRV responses.…”

“…34 Breathing effects on autonomic reflexes have been well described by Bernardi et al 3 and generate impact on HRV indexes, showing changes in spectral components, particularly due to changes in RF. 27 In this sense, we believe that the change in breathing pattern during exposure to hypoxia can impact on HRV. Furthermore, chemoreflex stimulation caused by hypoxia may also affect the autonomic control caused by sympathetic activation, which can be counterbalanced, for example, by either the interaction of baroreceptors or the inhibitory effect of pulmonary-stretch lung afferents.…”

Vagal activity and oxygen saturation response to hypoxia: Effects of aerobic fitness and rating of hypoxia tolerance

“…breaths per minute may lead to an artificial increase in the LF with concomitant changes in the LF/HF ratio due to an RSA peak shift from HF into the LF. This could be a limitation in terms of interpreting both the vagal and the sympathetic contribution to the sinoatrial node activity (Sasaki & Maruyama, 2014;Vlčková et al, 2005). To avoid the potential methodological issue of BF, HRV is frequently measured under paced breathing conditions (Botek et al, 2015;Roche et al, 2002).…”

Left Recumbent Position Decreases Heart Rate without Alterations in Cardiac Autonomic Nervous System Activity in Healthy Young Adults

“…Since this monitor is not sensitive to various body movements or noise (Shimpuku et al 2010), there was no risk of any artifact and it enabled us to measure ECG data precisely during the postural changes and in each position. The respiratory rate was measured visually across the three positions because a respiratory rate of < 9 cycles/min may lead to alterations in HRV (Patwardhan et al 1995;Sasaki and Maruyama 2014).…”