A new clinical study has found no benefit of ashwagandha supplementation on aerobic capacity, muscle oxygenation, or blood parameters in healthy men.
I don't take ashwagandha myself. But if you're currently taking it, this study doesn't necessarily mean you should stop — as I’ll explain in this article. Plus, at the end, I’ll share an alternative supplement with strong evidence for boosting exercise performance.
Table of Contents
- The new study
- The larger research context
- Mechanism and anxiety
- Creatine: A Better Option for Performance?
- Conclusion
- References
The New Study
Ashwagandha is a plant that’s been used for centuries in traditional Eastern medicine. Existing research has suggested it may offer benefits for exercise performance.
But this new study focused specifically on aerobic capacity and sought to explore the mechanisms behind any improvements. Here's how the study was set up, and what the researchers discovered.
Study Overview
The study included 41 healthy, non-athlete men. They were randomly assigned to one of two groups:
- One group took 600 mg of ashwagandha root extract daily
-
The other took a placebo
All participants completed 8 weeks of HIIT training using a rowing machine.
To evaluate ashwagandha’s effects, researchers measured:
- VO2max (maximal oxygen consumption)
- Muscle oxygenation
-
Blood parameters, including hemoglobin (Hb) and red blood cell (RBC) counts
These measurements were taken before and after the 8 weeks of training. The rationale was that if ashwagandha improves oxygen delivery through increased blood capacity, it could boost aerobic performance.
Results
When it came to aerobic performance, there were no statistically significant differences between groups.
- VO2max, maximum aerobic power, and power at anaerobic threshold were measured.
- But none of these showed improvements with ashwagandha supplementation.
The researchers concluded that there were no significant differences in the percentage changes in exercise capacity parameters.
Blood Markers
Researchers examined 15 distinct blood parameters including Hb and RBC. As with performance, they found no significant differences between the ashwagandha and placebo groups before or after the 8 weeks.
Conclusion of the Study
The final conclusion was clear: Ashwagandha supplementation does not appear to affect training-induced improvements in aerobic capacity in healthy men.
The HIIT training itself was effective, but equally so for both placebo and supplement groups. There were no notable differences in VO2max or blood metrics between the two.
The Larger Research Context
So… does this mean you should stop taking ashwagandha?
Not necessarily.
We need to place this recent study within the broader research landscape — and that context tells a more mixed and nuanced story.
Early Study: 2010
One of the first studies looking at ashwagandha for exercise was published in 2010. After 8 weeks of supplementation:
- VO2max increased by nearly 7%
-
Gains were also observed in sprint speed and leg muscle power
However, the study was very small — just 10 participants per group — limiting the reliability of the results.
Meta-Analysis: 2020
A 2020 systematic review pooled data from four studies and found that ashwagandha significantly improved VO2max.
But there were major limitations:
- Only one study measured VO2max directly
- Others relied on indirect indicators
- Evidence quality was rated as low
- Heterogeneity was high (I² = 84%), which reduces confidence in the result
Meta-Analysis: 2021
A separate meta-analysis in 2021 concluded that the impact of ashwagandha on cardiorespiratory fitness was very large, with a pooled VO2max effect size of nearly 2 — a substantial result.
However, like the previous analysis, it relied on small and methodologically varied studies, limiting the strength of its conclusions.
Dose and Duration: Important Factors
The authors of the most recent trial pointed out two limitations that could apply more broadly:
- Dose: They used 600 mg/day, but other studies have used 1,000 mg/day, which may be more effective.
-
Duration: The study lasted 8 weeks. A longer supplementation period might show stronger results.
So while earlier studies suggest potential benefits, this latest trial raises serious doubts. We need more high-quality research before drawing confident conclusions about ashwagandha's role in exercise performance.
Mechanism and Anxiety
Ashwagandha may still offer another kind of benefit — reducing stress and anxiety.
The Mechanism: HPA Axis Regulation
Ashwagandha appears to influence the hypothalamic-pituitary-adrenal (HPA) axis, which regulates the body’s stress response.
This system works as a chain reaction:
1. The hypothalamus detects stress
2. It signals the pituitary gland
3. The pituitary triggers the adrenal glands to release cortisol and adrenaline
Ashwagandha seems to help turn down this stress response, lowering cortisol levels.
Evidence in Anxiety Reduction
Study: 2009
Adults with moderate-to-severe anxiety were given either:
- Traditional psychotherapy and breathing techniques with a placebo
- Or naturopathic care, including breathing techniques and 300 mg of ashwagandha twice daily
After 8 weeks:
- The psychotherapy group had a 30.5% reduction in anxiety scores
- The ashwagandha group had a 56.5% reduction
Study: 2024
In a more recent trial:
- Anxiety scores dropped by 59% in the ashwagandha group
- Morning cortisol levels fell by 66–67%
- The placebo group showed almost no change
Meta-Analysis: 2024
A 2024 meta-analysis of 9 randomized trials involving 558 participants found that ashwagandha significantly reduced:
- Perceived stress
- Anxiety
- Cortisol levels
Clinical Application
For patients dealing with stress or anxiety, I often explain the current state of the evidence — including its limitations. If they’re interested in trying ashwagandha, I recommend looking for a product tested by ConsumerLab.com.
That’s because in their independent testing, only 5 out of 13 ashwagandha products passed — mainly due to low levels of active ingredients.
Having your supplement tested helps ensure you're actually getting what the label claims — and ConsumerLab is a reliable place to find that information. (And no, I’m not affiliated with them.)
Creatine: A Better Option for Performance?
Returning to exercise performance, there’s another supplement with much stronger and more consistent evidence: creatine.
Most people think of creatine for muscle, but its brain benefits are just as compelling — in fact, they’re what convinced my grandma to start taking it.
Why Creatine Matters for the Brain
Our brains use a tremendous amount of energy. Creatine supports the production of ATP — a rapid source of energy — making it essential for memory, focus, and processing speed.
Supplementation has been shown to increase brain creatine content, helping to support cognitive performance, especially under stress or in older age.
Meta-Analysis: 2022
This meta-analysis found that creatine supplementation improved memory, particularly in older adults (ages 66–76).
Meta-Analysis: 2024
This newer analysis included 16 randomized controlled trials with 492 participants. It found significant improvements in:
- Memory
- Attention time
- Processing speed
Importantly, it also showed that creatine was particularly beneficial for:
- Women
- Adults aged 18–60
- Individuals with underlying conditions
Important Note
Many of my female patients believe creatine is just for men. But the evidence shows it’s equally beneficial for women, particularly for cognitive performance.
I personally take creatine as part of my MicroVitamin+ Powder. That doesn’t mean you need to, but if you're looking for a well-supported supplement to improve both body and brain performance, creatine is worth considering.
Conclusion
Ashwagandha has long been promoted for athletic performance — but this most recent high-quality study shows no measurable benefit for exercise.
That doesn’t mean it’s useless. In the context of stress and anxiety, it still shows promise. But for those looking for a supplement with clear, consistent evidence of performance and cognitive benefits, creatine stands out as the better choice — for men and women alike.
References
1. https://pmc.ncbi.nlm.nih.gov/articles/PMC12244407/
2. https://pmc.ncbi.nlm.nih.gov/articles/PMC2996571/
3. https://pmc.ncbi.nlm.nih.gov/articles/PMC7230697/
4. https://pmc.ncbi.nlm.nih.gov/articles/PMC8006238/
5. https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/s12986-025-00902-7
6. https://pmc.ncbi.nlm.nih.gov/articles/PMC2729375/
7. https://pmc.ncbi.nlm.nih.gov/articles/PMC11402924/
8. https://pubmed.ncbi.nlm.nih.gov/39348746/
9. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8912287/
10. https://academic.oup.com/nutritionreviews/advance-article/doi/10.1093/nutrit/nuac064/6671817
