Ashwagandha for Athletes: This 6-Week Trial Found Sex-Specific Benefits for Stress and Recovery
Summary
If you've seen ashwagandha marketed as a "cortisol-lowering" adaptogen and wondered whether it actually holds up for people who train hard, this new study is worth knowing about. Researchers ran a 6-week, randomized, double-blind, placebo-controlled trial on 56 sub-elite team-sport athletes (rugby, water polo, and football players) in Barcelona during pre-season training — arguably one of the most physiologically stressful stretches of an athletic year, when cortisol tends to climb as training load ramps up.
Participants took either 600 mg/day of KSM-66 Ashwagandha root extract (standardized to >5% withanolides) or a visually matched placebo (chickpea flour capsules) with dinner for 42 days. Researchers measured post-training salivary cortisol, cortisone, testosterone, and DHEA-S; tracked subjective recovery using the Hooper Index (sleep, stress, fatigue, muscle soreness); and tested muscle strength, jump power, and aerobic capacity before and after the intervention.
The headline finding wasn't that ashwagandha "crushed" cortisol — it's more nuanced, and arguably more realistic. In female athletes, the placebo group's evening cortisol rose significantly over the 6 weeks (as would be expected from accumulating training stress), while the ashwagandha group's cortisol stayed essentially flat. The same stabilizing pattern showed up for cortisone (cortisol's inactive breakdown product) — but only in male athletes, where the placebo group's cortisone climbed while the ashwagandha group held steady. Testosterone and DHEA-S didn't differ between groups in either sex.
On top of the hormone story, the benefits split cleanly by sex. Female athletes taking ashwagandha reported meaningfully better overall recovery scores, less muscle soreness (DOMS), and lower fatigue than placebo. Male athletes didn't see those subjective recovery gains, but they did jump higher on the countermovement jump test (a marker of explosive lower-body power) compared to placebo. Pull-up performance improved in both groups — likely just a normal training effect. Grip strength, 1RM lifts (squat, bench, deadlift, power clean), standing broad jump, and the aerobic Bronco shuttle test showed no differences between groups.
This tracks with a broader body of evidence: a 2025 meta-analysis pooling 15 RCTs (873 participants) found ashwagandha reliably lowers cortisol, and past trials have shown benefits for stress and anxiety scores, generally at doses of 250–600 mg/day over 4–12 weeks. What's new here is testing it specifically in athletes under real training load, with hormones measured post-exercise rather than at rest, and with sexes analyzed separately rather than pooled — a design choice that turned out to matter, since pooling the sexes together would have hidden both effects.
Satisfaction scores also favored ashwagandha over placebo, and the supplement was well tolerated, with only one mild headache reported in the treatment group.
What This Means For You
If you're an athlete or serious trainee considering ashwagandha during a demanding training block (pre-season, a strength phase, or any period of high accumulated fatigue), this study supports a dose of 600 mg/day of a root-only extract standardized to >5% withanolides (the study used KSM-66 specifically), taken once daily with food, for at least 6 weeks. Look for "root extract" and a stated withanolide percentage on the label — the researchers specifically flag leaf extracts and unstandardized products as a liver-safety concern, since the compounds linked to potential liver injury (withanone, withaferin A) concentrate in the leaf, not the root.
Set expectations appropriately: this isn't a strength or power supplement in the way creatine is. The muscle-strength and aerobic-capacity outcomes were mostly unchanged; the real signal was in stress-hormone stability and subjective recovery (less soreness, less fatigue, better perceived readiness) for women, and slightly better jump power for men. If your priority is feeling less beat-up during a brutal training cycle rather than adding kilos to your squat, this is more relevant.
The sex-specific split is worth taking seriously rather than dismissing as noise — it lines up with known biological differences in how the stress-hormone (HPA) axis responds between men and women. Female athletes managing training-related fatigue or soreness may see more benefit from the recovery angle; male athletes concerned about explosive power during high-volume phases may see more benefit there.
People on medications should be cautious: ashwagandha may affect CYP3A4, an enzyme that metabolizes roughly a third to half of prescription drugs, so anyone on regular medication should check with a doctor or pharmacist first. Anyone with nightshade allergies, who is pregnant, or on hormonal contraceptives was excluded from this trial and should avoid it or seek medical advice.
Important Considerations
This was a small trial — 56 athletes total, just 14 per sex per group — so individual outcomes (like female-only recovery gains or male-only jump improvements) should be treated as promising rather than definitive; larger confirmatory trials are needed, and the authors themselves note the study wasn't designed specifically to test sex differences. Participants were sub-elite, convenience-sampled athletes from one Barcelona academy training in unusually hot, humid conditions (~30°C, 70–80% humidity) — heat itself raises cortisol, so results may not generalize to cooler climates, recreational exercisers, or non-athletes.
Many outcomes were tested (hormones, four Hooper Index subscales, multiple strength/power tests), and while the researchers applied Bonferroni correction, the sheer number of comparisons still raises some risk of chance findings — especially in secondary and subgroup analyses. Roughly a third of hormone values and over half the strength measurements were missing and had to be statistically imputed, which adds uncertainty. Diet wasn't tracked, despite being a known influence on both recovery and hormone levels.
This trial was funded by Ixoreal Biomed, the maker of KSM-66, which supplied the product and materials — a common industry-funding arrangement worth being aware of, though the trial was independently registered, double-blind, and placebo-controlled. Be skeptical of marketing that claims ashwagandha "lowers cortisol" as a blanket statement — this study found it mainly prevented cortisol/cortisone from rising during stress, rather than lowering it below baseline, and the effect differed by sex. Anyone with liver conditions, on prescription medication, pregnant, or with nightshade allergies should talk to a healthcare provider before starting ashwagandha.
Terms Explained
Technical Study Details
Study Design
Total Score
JADAD Quality Assessment評価詳細
Randomization
2 / 2Blinding
2 / 2Dropouts/Withdrawals
1 / 1Study Population
- Team sports athletes assigned to a professional sports academy in Barcelona, Spain
- Aged above 18 years
- Competing at a sub-elite level
- Classified as healthy or free from disease
Interventions
KSM-66 Ashwagandha root extract
TreatmentPlacebo (chickpea flour)
ControlOutcomes
| Outcome | Type | Effect | p-value |
|---|---|---|---|
| Salivary cortisol | Primary | - | p=0.01Significant |
| Salivary cortisone | Secondary | - | p=0.0003Significant |
| Salivary alpha-amylase | Secondary | - | p=0.022Significant |
| Salivary testosterone | Secondary | - | p=0.915 |
| Salivary DHEA-S | Secondary | - | p=0.386 |
| Testosterone-to-cortisol ratio (T/C) | Secondary | - | p=0.351 |
| Overall Hooper Index score | Secondary | - | p=0.005Significant |
| Delayed Onset Muscle Soreness (DOMS) | Secondary | - | p=0.0002Significant |
| Perception of fatigue | Secondary | - | p=0.015Significant |
| Perception of stress | Secondary | - | - |
| Sleep quality | Secondary | - | - |
| Handgrip strength | Secondary | - | - |
| Squat 1RM | Secondary | - | - |
| Bench press 1RM | Secondary | - | - |
| Deadlift 1RM | Secondary | - | - |
| Power clean 1RM | Secondary | - | - |
| Pull-up performance | Secondary | - | -Significant |
| Countermovement jump (CMJ) height | Secondary | - | p=0.0003Significant |
| Standing broad jump | Secondary | - | - |
| Bronco test (aerobic capacity) | Secondary | - | - |
| Supplement satisfaction | Secondary | - | p=0.0004Significant |
Safety
Conclusion
In this double-blind, placebo-controlled, randomised trial, 42 days of supplementation with 600 mg/day of Ashwagandha root extract during pre-season training led to sex-specific benefits compared with placebo: improved perception of recovery (Hooper Index, DOMS, fatigue) in female athletes and improved lower-body muscle strength (CMJ) in male athletes. Post-training salivary cortisol in females and salivary cortisone in males remained stable with Ashwagandha supplementation, whereas the placebo group showed significant increases, suggesting Ashwagandha may help stabilise physiological stress biomarkers during periods of elevated training-related hormonal responses.Limitations
- Convenience sampling was used, restricting external validity beyond the study sample
- Lack of a crossover design limits control for potential confounders
- Dietary intake was not recorded, a potential confounder for recovery and performance outcomes
- Baseline heterogeneity due to participants being drawn from three different sports with varying training backgrounds and performance levels
- Non-standardised order of assessments across participants
- Individual differences in circadian rhythms remain a potential limitation despite evening saliva collection to reduce circadian variation
- Multiple comparisons may increase risk of false-positive results despite Bonferroni correction
- Study was not specifically designed to investigate sex differences
- Participants were exposed to high ambient temperature (~30°C) and humidity (70-80%) during the trial, which may have influenced hormonal and performance responses
- Missing data (29 hormone values, 32 muscle strength values) required multiple imputation