Yoga, Meditation, Breathing Exercises, and Inflammatory Biomarkers with Possible Implications in COVID-19: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

INTRODUCTION: COVID-19, a multisystem disease, has implications for various immunity and infection biomarkers. Yoga (Y), meditation (M), and pranayama (P), and their combinations have shown positive changes on those biomarkers among other than COVID-19 patients and healthy people. So, we aimed to document the evidence of possible implication in a systematic way. MATERIALS AND METHODS: We screened 84 full texts, published in the last ten years, from three databases, from which only 44 met the eligibility criteria, and then extracted the data related to demographic characteristics, intervention, results, and strengths and limitations in two MS-Excel grids, and then presented them in tables and figures. Furthermore, we carried out meta-analysis including subgroup and sensitivity analysis using a random effects model of 11 RCTs and reported the mean difference, heterogeneity, and p value with 95% CI and presented them with forest and funnel plots and the tables. RESULTS: Twenty-five biomarkers of 4023 participants (range, 15–413) from 13 countries, healthy and clinical, from both sexes above 18 years, and from mainly clinical settings, were reported. YMP intervention, in solitary or in different possible combinations with varied durations among clinical and pregnant (range, 960–4800 minutes) and healthy (960–8400 minutes, excluding two studies of 20 minutes only) participants, was reported. It was revealed that 25 biomarkers, nine among the apparently healthy, 14 among the patients, and two among the pregnant, changed favourably (p < 0.05). Furthermore, either in meta- or subgroup-analysis, mean differences of IL-6 (−1.44 pg/ml) (95% CI) (−2.33, −0.55), (p = 0.002, I(2) = 82%), Cortisol (−40.75 pg/ml) (95% CI) (−64.13, −17.38), (p = 0.0006, I(2) = 87%), and TNF-α (−3.40 pg/ml) (95% CI) (−4.83, −1.98), (p < 0.0001, I(2) = 79%) showed statistically significant changes. Nonetheless, considerable heterogeneity and publication bias were observed among the studies. CONCLUSION: Although more than two dozens of biomarkers in individual studies showed favourable changes, only IL-6, Cortisol, and TNF-α produced significant combined results, even then with much less certainty. Further meta-analysis of biomarkers of COVID-19 patients is highly recommended. Registration: CRD42021283894.