HEART RATE VARIABILITY AND YOGA-BASED INTERVENTIONS: AN INTEGRATIVE REVIEW OF AUTONOMIC NERVOUS SYSTEM ADAPTATIONS

Abstract

Background: Heart rate variability (HRV) is a widely used non-invasive biomarker of cardiac autonomic regulation. Yoga-based interventions have shown promise in improving autonomic function; however, the available evidence remains heterogeneous. Objective: To synthesise current evidence on the effects of yoga-based interventions on HRV, examine the physiological mechanisms underlying autonomic adaptations, and identify research gaps, with particular emphasis on Surya Namaskar. Methods: This integrative review was conducted using the Whittemore and Knafl framework. A comprehensive literature search was performed in PubMed, Scopus, Web of Science, Embase, and Google Scholar for studies published in English evaluating the effects of yoga-based interventions on HRV in healthy and clinical populations. Randomized controlled trials, non-randomized clinical trials, cohort studies, and observational studies were included. Data were extracted on study characteristics, intervention protocols, HRV parameters, and major findings, and the evidence was synthesized narratively according to intervention type and proposed physiological mechanisms. Results: Most studies reported favourable effects of yoga on HRV, characterised by enhanced parasympathetic activity, reduced sympathetic dominance, improved baroreflex sensitivity, and favourable changes in both time-domain and frequency-domain HRV indices. Conclusion: Current evidence suggests that yoga-based interventions improve cardiac autonomic regulation as reflected by favourable changes in HRV. Nevertheless, well-designed, adequately powered randomised controlled trials using standardised intervention protocols, particularly for Surya Namaskar, are required to strengthen the evidence base.