Ashwagandha for Strength and Recovery: What the Gym Studies Really Show

Ashwagandha built its reputation as a stress herb, but lately it has moved from the nightstand to the gym bag. Supplement brands now sell it as a natural way to lift more, recover faster and even raise testosterone. Some of that marketing runs ahead of the science. Some of it, surprisingly, does not.

So we went through the human trials that actually tested ashwagandha in people who train, sorted each claim by how strong the evidence is, and noted the dose and extract each study used. Short version: there is a real, if small, body of research showing better strength gains when ashwagandha is added to a training program. It is not a steroid, the trials are short, and most were done on young men. Here is what they found, and who should not take it.

What ashwagandha is

Ashwagandha (Withania somnifera) is a shrub in the nightshade family, and the root has been used in Ayurvedic medicine for centuries. It is called an adaptogen, a loose term for herbs said to help the body cope with stress. The compounds researchers focus on are called withanolides. Most of the human studies did not use plain root powder. They used branded, standardized extracts, mainly KSM-66 (a root extract) and Sensoril or Shoden (root-and-leaf extracts). That detail matters when you shop, because a product that does not name its extract cannot be matched to any study.

If you want the bigger picture on stress and sleep, read our guide to the best ashwagandha supplements. This article sticks to training.

🏋️ Strength: the most interesting evidence

The trial most people cite was published in the Journal of the International Society of Sports Nutrition in 2015. Researchers took 57 young men who were new to strength training and put them all on the same eight-week lifting program. Half took 300 mg of KSM-66 twice a day, and half took a placebo. By the end, the ashwagandha group had made noticeably bigger gains on the bench press and leg extension, added more muscle size in the arms and chest, and showed less of a marker of muscle damage after workouts. They also lost slightly more body fat.

A second trial, the 2018 STAR trial in the journal Nutrients, gave 38 recreationally active men 500 mg a day of a different extract (Sensoril) or a placebo for 12 weeks of training. Again the ashwagandha group improved upper and lower body strength more than the placebo group.

In 2021, a team of sports scientists pooled the available randomized trials in a Bayesian meta-analysis published in the Journal of Functional Morphology and Kinesiology. They concluded that ashwagandha was more effective than placebo for improving strength and power, and for measures of fatigue and recovery.

Our read: for an herb, that is an unusually consistent set of results. But keep the limits in view. The trials are small, they last two to three months, most participants were men in their twenties and thirties, and several studies were funded by the companies that sell the extracts. Think of ashwagandha as a possible small edge on top of good training, food and sleep, not a replacement for any of them.

🫀 Endurance: a modest lift in VO2max

VO2max is the most oxygen your body can use during hard exercise, and it is a strong marker of aerobic fitness. A 2020 meta-analysis in Nutrients combined five small trials in athletes and healthy adults and found that ashwagandha improved VO2max more than placebo. The effect was modest and the studies were small, so we rate this as promising rather than proven. For runners and cyclists, consistent training will move the needle far more than any supplement.

🩹 Recovery and soreness

In the 2015 lifting trial, the ashwagandha group showed smaller rises in creatine kinase, an enzyme that leaks into the blood when muscle is damaged by hard exercise. The 2021 meta-analysis also found better scores on fatigue and recovery measures. That fits with ashwagandha’s stress research, since poor sleep and high stress both slow recovery. If soreness is your main complaint, though, food-based options like ginger also have human data behind them. We cover those in our natural workout recovery guide.

🧪 What about testosterone?

This is where the marketing gets loudest. Some trials did measure small increases in testosterone in men taking ashwagandha, including the 2015 lifting study. But the rises were modest, not every study found them, and they stayed within the normal range. Ashwagandha is not a testosterone booster in any meaningful medical sense. If you have symptoms of low testosterone, such as ongoing fatigue, low libido or loss of muscle despite training, see a doctor and get your levels tested properly.

How to use it, if you decide to try it

• Match the studied extract and dose. KSM-66 at 300 mg twice a day (600 mg total) is the best-studied setup for strength. Sensoril was studied at 500 mg a day.
• Give it eight to twelve weeks. Every positive trial paired ashwagandha with a structured training plan over two to three months.
• Take it with food. Stomach upset is one of the more common complaints.
• Cycle off. There is little research on use beyond three months, so many people take a break after a training block.
• If you compete, check testing. Ashwagandha itself is not a banned substance, but any supplement can be contaminated. Tested athletes should choose products certified by a program such as NSF Certified for Sport or Informed Sport.

Who should skip it or ask first

• Pregnant or breastfeeding. Ashwagandha is traditionally avoided in pregnancy, and the U.S. National Center for Complementary and Integrative Health (NCCIH) says it may be unsafe.
• Anyone with liver disease, or who notices dark urine, yellowing skin or eyes, or unusual tiredness while taking it. Rare cases of liver injury have been reported.
• People with thyroid conditions or on thyroid medication. It can raise thyroid hormone levels.
• People with autoimmune conditions or on immune-suppressing drugs, since it may stimulate the immune system.
• Anyone taking sedatives, sleep aids, blood pressure or blood sugar medicines. Effects may add up.
• Anyone with hormone-sensitive prostate cancer, given the possible effect on testosterone.

The honest bottom line

Ashwagandha has a better case in the gym than most herbs: a handful of small, placebo-controlled trials found bigger strength gains, a modest bump in aerobic fitness and possibly faster recovery. The research is short-term, mostly in young men, and partly industry-funded. If you want to try it, use a named extract at the studied dose for one training block, track your lifts and how you feel, and stop if your stomach, sleep or mood disagree with it.

Studies and sources

• Wankhede S et al. (2015). Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial. Journal of the International Society of Sports Nutrition, via PubMed.
• Ziegenfuss TN et al. (2018). Effects of an aqueous extract of Withania somnifera on strength training adaptations and recovery: the STAR trial. Nutrients, via PubMed.
• Bonilla DA et al. (2021). Effects of ashwagandha (Withania somnifera) on physical performance: systematic review and Bayesian meta-analysis. Journal of Functional Morphology and Kinesiology.
• Pérez-Gómez J et al. (2020). Effects of ashwagandha (Withania somnifera) on VO2max: a systematic review and meta-analysis. Nutrients.
• Ashwagandha: usefulness and safety. NCCIH.

This article is for general education and is not medical advice. Talk to your doctor or pharmacist before starting a supplement, especially if you take medication or have a health condition. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.