Increased exhalation to inhalation ratio during breathing enhances high‐frequency heart rate variability in healthy adults. (20th July 2021)

• Record Type: Journal Article
• Authors: Bae, Dalbyeol; Matthews, Jacob J. L.; Chen, J. Jean; Mah, Linda
• Is Part Of: Psychophysiology. Volume 58:Number 11(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-07-20
• Subjects: autonomic nervous system -- breathing -- heart rate variability; Psychophysiology -- Periodicals; 612.8
• DOI: 10.1111/psyp.13905
• Languages: English
• ISSNs: 0048-5772

Abstract

Abstract: Heart rate variability (HRV) is a well‐established surrogate of cardiac and emotional health that reflects the balance between sympathetic and parasympathetic activity of the autonomic nervous system. We examined the impact of manipulating exhalation to inhalation ratio (E:I) on HRV, without altering the intrinsic breathing rate of healthy individuals. We hypothesized that a longer exhalation relative to inhalation (E:I > 1) would shift HRV metrics in a direction consistent with increased parasympathetic activity. Twenty‐eight individuals (16 young [6M, age = 21–28];12 older adults [6M, age = 66–80]) completed a task during which they paced breathing according to their intrinsic respiratory rate, but altered onset of exhalation and inhalation according to 1:1 sound cue (equal exhalation and inhalation duration) or 2:1 cue (exhalation twice as long as inhalation). Paced 1:1 breathing followed these task conditions to examine residual effects. Estimates of actual E:I ratio based on thoracic movement were 1.08(0.16) for 1:1 task and 1.33(0.20) for 2:1 task, which were significantly different from one another. HRV metrics derived from electrocardiogram included root mean square of the successive differences between normal heartbeats (RMSSD) and high‐frequency (HF) HRV. Analyses of HRV metrics by block showed that RMSSD and HF‐HRV were higher in the 2:1 task condition compared to 1:1. Time series analysis showed that HF‐HRV increased after the end of the 2:1 task block and remained elevated for four minutes. These findings suggest that longer duration of exhalation relative to inhalation, without altering breathing rate, acutely increased RMSSD and HF‐HRV, consistent with enhancement of cardiac vagal tone. Abstract : Breathing strategies form the basis of many interventions for stress, but the specific changes in breathing patterns that lead to stress reduction remain unclear. We examined the impact of altering the duration of exhalation relative to inhalation on heart rate variability (HRV), a surrogate marker of emotional well‐being, in healthy young and older adults. The results from our study demonstrated that longer exhalation relative to inhalation, independent of breathing rate, increased time‐ and frequency‐domain HRV metrics, consistent with enhancement of cardiac vagal tone.