Adjunctive Ashwagandha (Withania somnifera) Supplementation and Resistance-Training Adaptations in Healthy Adults: A Systematic Review and Random-Effects Meta-Analysis of Muscular Strength, Chest Circumference, and Body Composition
Abstract
Background/Objectives: Ashwagandha (Withania somnifera) is increasingly marketed as an adjunct that amplifies the strength and muscle-size gains produced by resistance training. Prior meta-analyses pooled trials across mixed exercise contexts rather than trials confined to structured resistance training. We therefore quantified adjunctive ashwagandha effects on muscular strength, chest circumference and body composition within such trials. Methods: We searched twelve bibliographic sources (including PubMed/MEDLINE, Europe PMC, OpenAlex and Cochrane CENTRAL) and two trial registers (ClinicalTrials.gov, WHO ICTRP) without date restriction to 23 August 2026, with reference-list, included-study-list and forward-citation screening, for randomized controlled trials (RCTs) combining a standardized ashwagandha extract (root or root-and-leaf) with structured resistance training in healthy adults (PRISMA 2020). Screening, extraction and risk-of-bias assessment were duplicated independently. Change-from-baseline standardized mean differences (SMDs; Hedges g) were pooled with restricted maximum-likelihood random-effects models, with RoB 2, leave-one-out and Hartung-Knapp-Sidik-Jonkman (HKSJ) sensitivity analyses, and GRADE. Embase, Scopus, Web of Science and CINAHL were unavailable to us, but Embase- and CINAHL-derived records were retrieved indirectly through CENTRAL. Results: Four RCTs were eligible; three (n = 161) provided poolable data, and one preprint was reported narratively…
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Evidence Hub reads this as a meta-analysis, done in people. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid. Reported size: 161 participants or records.
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