Evidence-backed FAQ
Does ashwagandha build muscle?
The trial reported endurance and arm and chest circumference differences. Its full-text strength-change comparisons were not statistically significant, and circumference is not a direct measure of muscle tissue.[1]
Important limitations
The study randomized 80 adults and analyzed 73 after compliance exclusions; it used KSM-66 root extract, 300 mg twice daily for eight weeks alongside resistance training. Full-text Tables 3 and 4 do not support the abstract’s broad claim of greater strength improvement. Circumference measurements do not establish increased muscle tissue. This single trial does not establish effects without training, in other populations or with other preparations.[1]
What the evidence shows
The study randomized 80 adults and analyzed 73 after compliance exclusions; it used KSM-66 root extract, 300 mg twice daily for eight weeks alongside resistance training. Full-text Tables 3 and 4 do not support the abstract’s broad claim of greater strength improvement. Circumference measurements do not establish increased muscle tissue. This single trial does not establish effects without training, in other populations or with other preparations.[1]
What the cited evidence shows
In one randomized placebo-controlled trial of active adults undertaking resistance training, ashwagandha root extract was associated with greater improvements in estimated cardiorespiratory endurance and arm and chest circumference; bench-press and leg-extension strength changes and thigh circumference changes did not differ significantly between groups. The study randomized 80 adults and analyzed 73 after compliance exclusions; it used KSM-66 root extract, 300 mg twice daily for eight weeks alongside resistance training. Full-text Tables 3 and 4 do not support the abstract’s broad claim of greater strength improvement. Circumference measurements do not establish increased muscle tissue. This single trial does not establish effects without training, in other populations or with other preparations.[1]
Safety belongs in the decision
NIH guidance describes short-term tolerability observations for ashwagandha over about three months, while safety over longer periods remains unknown. Short studies cannot establish safety for every person, preparation, or duration of use.[2]
Read the supporting evidence summaries
The linked research pages provide study populations, formulations, doses, outcomes, and limitations in greater detail.
Related questions
References
- Effects of Ashwagandha ( Withania somnifera) standardized root extract on physical endurance and VO (2max) in healthy adults performing resistance training: An eight-week, prospective, randomized, double-blind, placebo-controlled study.. F1000Research. 2024. Randomized controlled trial View source →
- Ashwagandha: Usefulness and Safety. NIH National Center for Complementary and Integrative Health. Retrieved 2026-09-30. Government health fact sheet View source →