Understanding Mind-Body Disciplines: A Pilot Study of 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 exactly how these activities 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: 1) rhythmic breathing alone, 2) alternating upper extremity muscle contractions, 3) combined rhythmic breathing with alternating contractions, or a 4) neutral control task. Autonomic response was assessed by heart rate variability during the standardized cognitive stressor. The alternating contraction group had a 71.7% higher activation of parasympathetic signal over respiration alone (p<0.001). Alternating contractions synchronized with breathing demonstrated a 150% higher parasympathetic activation than control (p<0.0001). Between contraction alone and combined contraction groups, the combined group demonstrated 45.9% higher parasympathetic response during a cognitive stressor (p<0.001). In conclusion, breathing combined with rhythmic muscle contraction led to greater activation of the parasympathetic response than either alternating contractions or breathing alone, which may help explain the stress reducing benefits of mind-body disciplines.