title: Inhalation/Exhalation ratio modulates the effect of slow breathing on heart rate variability and relaxation.
abstract: Slow breathing is widely applied to improve symptoms of hyperarousal, but it is unknown whether its beneficial effects relate to the reduction in respiration rate per se, or, to a lower inhalation/exhalation (i/e) ratio. The present study examined the effects of four ventilatory patterns on heart rate variability and self-reported dimensions of relaxation. Thirty participants were instructed to breathe at 6 or 12 breaths/min, and with an i/e ratio of 0.42 or 2.33. Participants reported increased relaxation, stress reduction, mindfulness and positive energy when breathing with the low compared to the high i/e ratio. A lower compared to a higher respiration rate was associated only with an increased score on positive energy. A low i/e ratio was also associated with more power in the high frequency component of heart rate variability, but only for the slow breathing pattern. Our results show that i/e ratio is an important modulator for the autonomic and subjective effects of instructed ventilatory patterns.
authors.affiliation: Faculty of Psychology and Educational Science, KULeuven, Tiensestraat 102, 3000, Leuven, Belgium, Ilse.VanDiest@ppw.kuleuven.be.
authors.forename: Ilse
authors.initials: I
authors.lastname: Van Diest
authors.forename: Karen
authors.initials: K
authors.lastname: Verstappen
authors.forename: André E
authors.initials: AE
authors.lastname: Aubert
authors.forename: Devy
authors.initials: D
authors.lastname: Widjaja
authors.forename: Debora
authors.initials: D
authors.lastname: Vansteenwegen
authors.forename: Elke
authors.initials: E
authors.lastname: Vlemincx
mesh_terms: D000328:Adult; D045853:Exhalation / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D012063:Relaxation / Q000502:physiology / Q000523:psychology*; D056152:Respiratory Rate / Q000502:physiology*; D065809:Respiratory Sinus Arrhythmia / Q000502:physiology; D055815:Young Adult