Effects of metronome guided breathing versus volitionally regulated yoga breathing on autonomic and respiratory variables

Abstract

Volitional breathing involves breath awareness along with modification of breath newlinecharacteristics including the breath rate, depth of breathing and the relative duration of newlineinspiration to expiration (i/e). The inspiration and expiration phases involve complex newlineneurological and mechanical mechanisms, significantly impacting human physiology. The newlinepractice of controlled breathing in yoga, can be practiced both intrinsically (through personal newlinepractice) and extrinsically (with the aid of devices). The present study examined and compared newlinethe effects of (i) breathing with high i/e, equal i/e, and low i/e, ratios at 12 bpm, and (ii) newlinebreathing with low i/e through a metronome and volitionally (bhramari pranayama), on newlineautonomic and respiratory variables (i.e. (i) heart rate variability (HRV), (ii) Galvanic skin newlineconductance (GSC), (iii) finger plethysmogram amplitude (FPA), (iv) non-invasive blood newlinepressure (NIBP) (v) respiratory variables), measures of affect (i.e. (i) brief mood introspection newlinescale, and (ii) global vigor and affect scale) and performance in a six letter cancellation test. newlineThe present randomized self as control crossover study recruited forty healthy participants newline(male: female; 1:1), age between 20 and 40 years, from a yoga university, where each newlineparticipant underwent five distinct sessions over consecutive days, with each session lasting 42 newlineminutes. The sessions were three metronome guided breathing sessions (high i/e, equal i/e, and newlinelow i/e), one volitional breathing session (bhramari pranayama) and one control session (quiet newlinesitting). Assessments were divided into (i) twenty-eight minutes for continuous physiological newlineassessments (autonomic and respiratory variables) and (ii) fourteen minutes for psychological newlineassessments (which were conducted before and after each session). newlineRepeated Measures ANOVA (RM-ANOVA) results revealed that all the four breathing newlinepractices (high i/e, equal i/e, low i/e and bhramari pranayama) significantly increased vagus newlinenerve activity.