Abstract 13772: The Cardiac Autonomic Reactivity in Long-Term Female Yoga Practitioners: A Comparison With Runners and Sedentary Individuals

Abstract

Introduction: Yoga practice, a means of stress management, has been reported to optimize psychophysiological health; however, its underlying mechanisms remain unclear. The purpose of the present study was to examine the cardiac autonomic reactivity in long-term yoga practitioners and compared that to runners and sedentary individuals. Hypothesis: The level of cardiac autonomic reactivity in yoga practitioners would be greater than that in the sedentary individuals but similar to that in the runners. Methods: Female individuals aged 20-50 years old with BMI 18.5-30 kg/m 2 were recruited. Participants in the yoga (or running) group regularly performed yoga (or running) for ≥ 90 minutes/week, for at least 2 years. Participants who did not regularly perform any type of physical activity were assigned to the sedentary group. Blood pressure (BP), heart rate (HR), respiration rate (RR) and heart rate variability (HRV) parameters (e.g., high frequency normalized unit (HFnu), the square root of the mean squared differences of successive normal-to-normal intervals (RMSSD), total power (TP) and standard deviation of normal-to-normal (SDNN)) were recorded at rest, during and following psychological stress, which was elicited by the Stroop color-and-word test (SCWT) and the mental arithmetic task (MAT). Outcome variables in the 3 groups were compared at multiple phases using Group x Time mixed design ANOVA and Bonferroni post-hoc comparison. Results: Yoga group demonstrated a lower RR (10.4±2.1 bpm) as compared to the other 2 groups, and a lower HR (66.6±7.6 bpm) and diastolic BP (67.8±8.4 mmHg) at rest as compared to the sedentary group (all p<0.05). HFnu following mental stress returned to the baseline in yoga (35.7±16.0 vs. 43.5±20.5) and running groups (44.7±17.1 vs. 52.0±18.0), but not in the sedentary group (29.9±22.0 vs. 43.1±18.3, p< 0.05). Similar results were observed in RMSSD and TP, where the level of outcome variables at the recovery phase returned to baseline in the yoga and running group, but not in the sedentary group. Conclusions: Yoga practitioners may have a greater homeostatic capacity and autonomic resilience than do sedentary individuals. The level of autonomic reactivity in long-term yoga practitioners was similar to that in the runners.