Comparison of Respiratory Sinus Arrhythmia between Zen-meditation and Control Groups

Background: This research aims to develop new methods to investigate the cardiorespiratory interaction of Zen-meditation practitioners (Zen-meditation group) and healthy ordinary young people (control group) by quantitatively evaluating respiratory sinus arrhythmia (RSA) behavior.

Methods: Twenty-five voluntary controls and seven Zen-meditation practitioners were recruited. The experimental protocol involved five sessions of different mental-stress levels (control group) and five sessions of Zen-meditation practice (experimental group). Forty minute ECG and respiratory signals were recorded for each control subject; thirty for each experimental subject. By detecting R peaks, heart-rate sequence is constructed. Two methods are proposed to evaluate RSA behavior based on cycle-to-cycle synchronization between heart-rate and respiratory sequence.

Results: Based on the proposed method of computing for a RSA coefficient, the control group average for each session was 0.70 (Rest I), 0.65 (continuous attention task, CAT I), 0.75 (BC), 0.63 (CAT II) and 0.70 (Rest II); whereas the Zen-meditation group average was 0.81 (S1), 0.84 (S2), 0.84 (S3), 0.86 (S4) and 0.81 (S5), all superior to the control group. The average RSA normal rate in the Zen-meditation group (91.03%) remarkably surpassed the control group (80.48%) in the Rest sessions.

Conclusions: Using the time-domain HRV (heart-rate variability) as a reference, our methods, RSA coefficient and RSA normal rate, provide more reliable and direct estimate of RSA behavior than the conventional peak-valley method computing the inspiratory–expiratory difference in R-to-R interval of ECG. Moreover, results of the proposed methods confined in a specified range (RSA coefficient between 0 and 1, RSA normal rate between 0% and 100%) facilitate the interpretation of the quantitative RSA behavior. In the RSA analysis, breathing control sessions using anthropic interventions induced more prominent RSA activity in the control group. Nevertheless, HHIS Zen meditation, with excellent qi circulation activated by the ten-mailuns system, naturally (in the way of do-nothing) elicits superior RSA performance, better than sophisticated breathing control.