Effects of a 12-Week Yogic Breathing Intervention on Metabolic Syndrome Severity and Cardiovascular Risk Factors: A Randomized Controlled Trial

AIMS: To evaluate the effects of Yogic breathing (Sudarshan Kriya Yoga [SKY]) on conventional and atypical cardiovascular risk factors in adults with metabolic syndrome (MetS). METHODS: In this 12-week, two-arm randomized controlled trial, 72 adults (30-60 years) with MetS were randomized (1:1) to SKY plus standard care or waitlisted standard care control group. Conventional and atypical cardiovascular risk factors, spanning behavioral, biological, inflammatory, oxidative, and autonomic markers, were assessed at baseline and 3 months. Between-group effects were evaluated by ANCOVA (adjusted for baseline values and medication use) using per-protocol (PP) and intention-to-treat (ITT; last observation carried forward) analyses. RESULTS: 64 participants completed follow-up (SKY, n=34; control, n=30). Improvements consistent across PP and ITT occurred in waist circumference (p=0.025/0.035), MetS severity score (MetSSS) (p=0.020/0.014), and heart rate variability (HRV) low-frequency (LF) and high-frequency (HF) power (p=0.035/0.010). Self-regulation of eating behavior, systolic blood pressure (SBP), and LF/HF ratio were significant only under ITT (p=0.0498, 0.035, 0.041), not PP (p=0.146, 0.056, 0.118). No significant between-group differences were observed for other outcomes. Within SKY, changes in HF power and superoxide dismutase (SOD) correlated inversely with changes in MetSSS (r=-0.36, p=0.039; r=-0.55, p=0.001). No adverse events occurred. CONCLUSION: 12-week of SKY improved waist circumference, MetS severity, and selected HRV measures in MetS adults. These findings were robust across analyses, while other outcomes were non-significant or inconsistent. Exploratory associations between HRV, SOD, and MetSSS warrant testing in larger, longer-duration trials. TRIAL REGISTRATION: Prospectively registered with the Clinical Trials Registry of India (CTRI/2023/08/056540) on 16-Aug-2023.