Pérez-Gómez et al. 2020, Ashwagandha and VO₂max systematic review and meta-analysis

Pérez-Gómez J, Villafaina S, Adsuar JC, Merellano-Navarro E, Collado-Mateo D. “Effects of Ashwagandha (Withania somnifera) on VO2max: A Systematic Review and Meta-Analysis.” Nutrients 2020;12(4):1119. DOI: 10.3390/nu12041119.

Systematic review (5 studies, 162 participants) and meta-analysis (4 studies, 142 participants) of Withania somnifera supplementation and maximal oxygen uptake. Pooled VO₂max improved by a mean difference of 3.00 mL·kg⁻¹·min⁻¹ (95% CI 0.18–5.82, p = 0.04), but the confidence interval nearly touches zero and heterogeneity was very high (I² = 84%). Doses ranged 300–1000 mg/day over 2–12 weeks (KSM-66, aqueous root extract and root powder), and every trial was conducted in India, in healthy adults and athletes aged 16–45. The authors rated overall evidence quality low by GRADE, citing few studies, small samples, high heterogeneity and unclear blinding, and concluded only that ashwagandha “might improve” VO₂max. Weak.