Understanding mind-body disciplines: A pilot study of paced breathing and dynamic muscle contraction on autonomic nervous system reactivity

Abstract

Mind-body disciplines such as yoga, Tai Chi, and Qigong have been demonstrated to activate the parasympathetic nervous system, but it remains unclear how these practices achieve these results, whether by breathing, movement, or some combination. This pilot study establishes a model to examine the individual and combined effects of paced breathing and rhythmic skeletal muscle contraction on the activation of the parasympathetic system during a cognitive stressor. Male participants were randomly assigned to one of four preconditioning groups: (a) paced breathing alone, (b) alternating upper extremity muscle contractions, (c) paced breathing synchronized with alternating contractions, or (d) a neutral control task. Autonomic response was assessed by heart rate variability during a standardized cognitive stressor. The alternating contraction group had 71.7% higher activation of parasympathetic signal over respiration alone (p < .001). Alternating contractions synchronized with breathing demonstrated 150% higher parasympathetic activation than control (p < .0001). Comparing the contraction alone and synchronized groups, the synchronized group demonstrated 45.9% higher parasympathetic response during a cognitive stressor (p < .001). In conclusion, paced breathing synchronized with rhythmic muscle contraction leads to more resilient activation of the parasympathetic response than either alternating contractions or breathing alone, which may help explain the stress reducing benefits of mind-body disciplines.

Keywords: biological mechanisms of stress; cardiovascular reactivity; mindfulness; psychophysiology; respite/recovery resilience; stress; stress management.

Conflict of interest statement

CONFLICT OF INTEREST

The authors have declared that they have no conflict of interest.

© 2019 John Wiley & Sons, Ltd.

Figures

FIGURE 1

Examples of heart rate variability (HRV) data after frequency analysis. After R-R interval data were processed in Kubios HRV Premium, fast Fourier transformation spectral analysis was performed separating the HRV power into low frequency (LF) and high frequency (HF) components. For comparison, the autonomic state during the Stroop test was normalized to baseline reading for each subject

FIGURE 2

(a) Parasympathetic response (high frequency [HF]). There was no significant difference in HF between breathing alone group and reading control during the Stroop test. Alternating contraction group had 71.7% higher activation of HF heart rate variability (HRV) over respiration alone (p < .001). Alternating contractions synchronized with breathing demonstrated 150% higher parasympathetic activation than control (p < .0001). Between the contraction alone and synchronized groups, the synchronized group demonstrated 45.9% higher parasympathetic response (p < .001). (b) Sympathetic response (low frequency [LF]). LF activation during administration of the Stroop test did not demonstrate a difference between breathing alone group and reading control. The alternating contraction group and synchronized groups had 33.5% and 45.2% lower LF activation over control respectively (p < .01 and p < .0001). There was no significant difference in LF response between contraction alone and synchronized groups. (c) Sympathovagal balance (LF/HF). There was no significant LF/HF ratio difference between breathing alone group and reading control. Both contraction groups had significantly less sympathetic activation over control respectively (p < .01 and p < .001). There was no significant difference in LF response between contraction alone and synchronized groups