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Ashwagandha and strength and power output: grade C

Limited evidence. Direction: Benefit.

C LimitedIndustry-fundedShort-term only

Educational guidance, not medical advice

Why this grade

Rubric condition met: The rubric default to the lower grade: >=2 RCTs with mostly consistent results (3 pooled RCTs) meet the literal B condition, but certainty is low, the estimates are fragile and no preregistered independent RCT is positive

A 2026 meta-analysis of resistance-training trials found greater 1-RM gains than placebo, but certainty was low, both estimates lost significance under HKSJ adjustment, and all three pooled trials were funded or supplied by manufacturers. A second meta-analysis found strength gains mainly in physically active people. Graded C under policy rule G3: the literal B condition is met, but neither a population-restricted meta-analysis with robust estimates nor a preregistered independent positive RCT supports B.

How we grade evidence

Studies this grade rests on

EffectMixedNo effectSize shows participants (n)2015202020252030Meta-analysisRCTZhu 2026, 2026: meta-analysis, n = 1,249, result not recordedLi 2026, 2026: meta-analysis, n = 599, result not recordedLee 2026, 2026: meta-analysis, n = 161, result not recordedWankhede 2015, 2015: RCT, n = 57, result not recorded
each study this grade rests on, by publication year and design. Solid: effect versus the comparator; half-filled: mixed; hollow: no effect; dashed: result not recorded yet. Larger marks had more participants.
Show the numbers
StudyYearDesignParticipantsResult
Wankhede 20152015RCT57result not recorded
Li 20262026meta-analysis599result not recorded
Zhu 20262026meta-analysis1249result not recorded
Lee 20262026meta-analysis161result not recorded

Effects of Withania somnifera (Ashwagandha) Supplementation on Exercise Performance: A Systematic Review and Three-Level Meta-Analysis.

Li X, Li H, Yao S. Effects of Withania somnifera (Ashwagandha) Supplementation on Exercise Performance: A Systematic Review and Three-Level Meta-Analysis Nutrients, 2026. PMID 42356302

Result not recorded
Design
Systematic review and three-level meta-analysis of 13 RCTs
Sample
n = 599
Population
Mainly young adults or athletes
Funding
National Education Science Planning Foundation of China, National Education Science Planning Foundation of China No.BLA230107

Effects of Withania somnifera (L.) Dunal (Ashwagandha) on cognitive and physical function in adults: a systematic review and meta-analysis.

Zhu X, Zeng Q, Lei Y. Effects of Withania somnifera (L.) Dunal (Ashwagandha) on cognitive and physical function in adults: a systematic review and meta-analysis Front Pharmacol, 2026. PMID 42199854

Result not recorded
Design
Systematic review and meta-analysis of 20 RCTs
Sample
n = 1,249
Population
Adults (mixed healthy, physically active and special populations)
Funding
not stated

Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial.

Wankhede S, Langade D, Joshi K. Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial J Int Soc Sports Nutr, 2015. PMID 26609282

Result not recorded
Design
Randomized, double-blind, placebo-controlled trial, 8 weeks
Sample
n = 57
Population
Young men with little resistance-training experience
Funding
not stated (paper declares no conflicts); extract made by Ixoreal BioMed

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.

Lee JC, Heo AS. 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 Nutrients, 2026. PMID 42738987

Result not recorded
Design
Systematic review and meta-analysis of RCTs (4 eligible, 3 pooled)
Sample
n = 161
Population
Healthy adults doing structured resistance training
Funding
No external funding (paper)

Search and history

Search (): ashwagandha[ti] AND (strength[tiab] OR muscle[tiab] OR VO2max[tiab] OR exercise[tiab]) AND (meta-analysis[pt] OR systematic review[pt])

  • Graded B (proposed): Proposed in the monograph draft
  • B to C (proposed): Updated in the monograph draft
  • C to C (approved): Editor sign-off November 13, 2026: grade matches the editor-approved final page