Yoga for Heart Rate Variability: A Systematic Review and Meta-analysis of Randomized Clinical Trials
- 1.1k Downloads
The objective of this systematic review is to summarize and critically assess the effects of yoga on heart rate variability (HRV). Nine databases were searched from their inceptions to June 2014. We included randomized clinical trials (RCTs) comparing yoga against any type of control intervention in healthy individuals or patients with any medical condition. Risk of bias was assessed using the Cochrane criteria. Two reviewers performed the selection of studies, data extraction, and quality assessments independent of one another. Fourteen trials met the inclusion criteria. Only two of them were of acceptable methodological quality. Ten RCTs reported favourable effects of yoga on various domains of HRV, whereas nine of them failed to do so. One RCT did not report between-group comparisons. The meta-analysis (MA) of two trials did not show favourable effects of yoga compared to usual care on E:I ratio (n = 61, SMDs = 0.63; 95 % CIs [−0.72 to 1.99], p = 0.36; heterogeneity: r2 = 0.79, χ 2 = 5.48, df = 1, (p = 0.02); I2 = 82 %). The MA also failed to show statistically significant differences between the groups regarding the 30:15 ratio (n = 61, SMDs = 0.20; 95 % CIs [−0.43 to 0.84], p = 0.53; heterogeneity: r2 = 0.07, χ 2 = 1.45, df = 1, (p = 0.23); I2 = 31 %). The data from the remaining RCTs were too heterogeneous for pooling. These results provide no convincing evidence for the effectiveness of yoga in modulating HRV in patients or healthy subjects. Future investigations in this area should overcome the multiple methodological weaknesses of the previous research.
KeywordsHeart rate variability Complementary and alternative medicine Yoga Systematic review Effectiveness
Conflict of interests
All authors declare no conflict interests.
- Ernst, E., Pittler, M. H., Stevinson, C., & White, A. R. (2006). The desktop guide to complementary and alternative medicine. Edinburgh: Mosby, 2nd ed.Google Scholar
- Kanojia, S., Kumar Sharma, V., Gandhi, A., Kapoor, R., Kukreja, A., & Kumar Subramanian, S. (2013). Effect of yoga on autonomic functions and psychological status during both phases of menstrual cycle in young healthy females. Journal of Clinical and Diagnostic Research, 7(10), 2133–2139.PubMedCentralPubMedGoogle Scholar
- Murugesan, M. (2013). Effect of yoga on heart rate variability-clinical implications in cardiovascular diseases. Vancouver, BC, Canada: International Academy of Cardiology 18th World Congress on Heart Disease Annual Scientific Sessions.Google Scholar
- Nolan, R. P., Jong, P., Barry-Bianchi, S. M., Tanaka, T. H., & Floras, J. S. (2008). Effects of drug, biobehavioral and exercise therapies on heart rate variability in coronary artery disease: A systematic review. European Journal of Cardiovascular Prevention and Rehabilitation, 15(4), 386–396.PubMedCrossRefGoogle Scholar
- Okoro, C. A., Zhao, G., Li, C., & Balluz, L. S. (2013). Has the use of complementary and alternative medicine therapies by U.S. adults with chronic disease-related functional limitations changed from 2002 to 2007? The Journal of Alternative and Complementary Medicine, 19(3), 217–223.PubMedCrossRefGoogle Scholar
- Santaella, D. F., Devesa, C. R., Rojo, M. R., et al. (2011). Yoga respiratory training improves respiratory function and cardiac sympathovagal balance in elderly subjects: A randomised controlled trial. BMJ Open, 1(1), e000085. doi: 10.1136/bmjopen-2011-000085.PubMedCentralPubMedCrossRefGoogle Scholar
- Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. (1996). Heart rate variability: standards of measurement, physiological interpretation and clinical use. Circulation 1, 93(5):1043–1065.Google Scholar