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

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.