Effects of relaxation and diaphragmatic breathing on respiratory sinus arrhythmia: Implications for cardiovascular disease.

Abstract

Respiratory sinus arrhythmia (RSA) has been shown to be a sensitive noninvasive index of parasympathetic cardiac control with empirical evidence supporting its utility in the study of numerous cardiac problems including: cardiac arrhythmias, sudden cardiac death and as a prognostic indicator of recovery after myocardial infarction. Respiratory modulation of vagal tone causes a reduction in heart period during inspiration and an increase in cardiac parasympathetic functioning during expiration. This pattern of change would be expected to increase if individuals were trained in diaphragmatic breathing. Spectral analysis of the respiratory frequency band was used to determine if the relaxation techniques studied, diaphragmatic breathing and autogenic training, had a differential effect on cardiac autonomic nervous system functioning. The current study evaluated the respiratory sinus arrhythmia in college students (N = 160) under the four experimental conditions (baseline, diaphragmatic breathing, modified autogenic training technique, and concentration task). Spectral analysis of RSA was employed to assess the relationship between vagal tone, diaphragmatic breathing and modified autogenic training. As hypothesized, diaphragmatic breathing consistently increased vagal tone when compared to baseline, modified autogenic training, and a concentration task. The modified autogenic training effect evidenced no increase in vagal tone. Indeed, the mean area under the respiratory band for this technique was less than baseline the results. The results of this study suggest that specificity of psychophysiological interventions is necessary to produce effects that improve cardiac functioning. A second implication is that the limited effects relaxation methods have had in the past in the treatment of cardiovascular problems (i.e., hypertension) may be secondary to lack of specificity of the techniques employed. Finally, bringing cardiac parasympathetic functioning under increased voluntary control may increase our ability to treat cardiovascular disease processes in a safe and cost effective way.