Is ashwagandha a performance supplement?
Does Ashwagandha Make You Fitter? What 13 Trials Actually Show
· By Anthony Falcone
Verdict: Keep it, with a caveat. Maybe, a little, for endurance. The average effect was small-to-moderate, but results varied so much that a new trial could easily find nothing. It is not an all-round performance booster.
What the researchers did
The team pooled every randomised trial they could find that compared oral ashwagandha with a placebo or control and measured real performance: endurance, strength, power or muscular endurance.
What they found
On average, ashwagandha improved performance by a small-to-moderate amount. But the range of likely results in a future trial runs from no effect (or slightly negative) to a clear benefit.
Endurance had the most consistent result. Strength looked positive but uncertain. For power and muscular endurance there wasn't enough good evidence to say anything.
Doses of 500–600 mg a day of extract had the most data behind them, but the authors warn that products differ a lot in plant part, extraction and active content, so milligrams don't compare cleanly between brands.
The authors rate their confidence as moderate-to-low: few trials, varied products, and many studies that didn't report training, diet or blinding well.
Safety
The included trials generally reported ashwagandha as well tolerated in the short term, with occasional sleepiness, dizziness or stomach upset. The authors also note case reports of reversible liver injury linked to ashwagandha products, and advise third-party-tested products for athletes.
What this means for you
- Don't take ashwagandha expecting it to raise your strength or power.
- If you use it, it's more plausibly a stress-and-recovery support than a pre-workout.
- Choose a third-party-tested product, and talk to your doctor first if you have liver issues, thyroid issues, are pregnant or take medication.
How much to trust it
- Only 13 trials, many small, with different products and doses.
- Most participants were young men or athletes; women were under-represented or not reported.
- Only English-language studies were included.
The study
Li X, Li H, Yao S, Hou Y, et al. Effects of Withania somnifera (Ashwagandha) Supplementation on Exercise Performance: A Systematic Review and Three-Level Meta-Analysis. Nutrients, 2026. doi.org/10.3390/nu18121915
Our HRV & Stress Protocol puts adaptogens like ashwagandha in context alongside the stress tools with stronger evidence: breathing, sleep and training load. See the protocol