Ashwagandha and Strength Gains: What the Wankhede 2015 Trial Actually Showed
The strength data on ashwagandha is more specific than the marketing suggests. Here’s the real protocol, the real numbers, and how to apply them honestly.
Quick answer: The flagship strength trial is Wankhede 2015 — 57 men, 600mg/day KSM-66®, 8 weeks of resistance training. Bench press improved +46kg vs +26.4kg in placebo. Muscle size, recovery, and testosterone all improved. Optibio® Ashwagandha KSM-66® uses the same dose.†
If you’ve been training for years, you know how rare it is to find a supplement — outside of creatine — that has clean strength data behind it. Most products in the “testosterone support” aisle are blends of underdosed ingredients with no replicated trials. Ashwagandha is one of the few exceptions.
The Wankhede 2015 trial in detail
Published in the Journal of the International Society of Sports Nutrition, the trial tested 600mg/day KSM-66® against placebo in healthy men starting an 8-week resistance training program. Both groups followed the same lifting protocol.
- 1RM bench press: KSM-66® +46kg, placebo +26.4kg
- 1RM leg extension: KSM-66® +14.5kg, placebo +9.8kg
- Arm circumference: +8.6cm vs +5.3cm
- Chest size: +3.3cm vs +1.4cm
- Body fat: KSM-66® group lost more body fat percentage
- Testosterone: KSM-66® group +96.2 ng/dL increase vs +18 ng/dL placebo
- Recovery: Lower post-exercise creatine kinase — less muscle damage to recover from
Two things worth noting honestly: first, the subjects were beginners. Beginner gains are bigger than intermediate gains, so don’t expect identical numbers if you’ve been training five years. Second, the trial was reasonably small (57 men) but well-designed — randomized, double-blind, placebo-controlled.
What the 2025 evidence adds
The 2025 Turkish Journal of Sports Medicine meta-analysis pooled six RCTs in athletic populations and confirmed improvements in core strength alongside the headline VO2max effect. And the 2025 12-month KSM-66® safety study found a significant testosterone increase across the 191-adult cohort sustained over 12 months — relevant for anyone using ashwagandha as a long-term strength-support tool, not just an 8-week experiment.
Why the strength effect probably runs through cortisol and testosterone
Cortisol and testosterone work in opposition for muscle adaptation. High cortisol = catabolic; testosterone = anabolic. Ashwagandha’s effect on the testosterone-to-cortisol ratio — raising testosterone modestly while reducing cortisol meaningfully — shifts that balance in a hypertrophy-friendly direction.
It’s not a steroid effect. The testosterone increase in Wankhede 2015 was modest in absolute terms but consistent. Stack that on top of an actual training program and the compounded gains are what shows up in the strength numbers.
Frequently asked questions
Will I bench +46kg in 8 weeks if I take ashwagandha?
If you’re a complete beginner with quality programming and good sleep, possibly. If you’ve been training 3+ years, no — intermediate gains don’t scale that way regardless of supplements. The directional effect (more progress with the supplement than without) is what generalizes.
Is ashwagandha better than creatine for strength?
No, and you wouldn’t pick one. Creatine is the most-replicated ergogenic supplement in sports nutrition; the effect size is large. Ashwagandha works on a different mechanism (cortisol/testosterone) and stacks cleanly. Run both.
Can ashwagandha replace testosterone replacement therapy?
No. The testosterone increase in clinical trials is modest. If you have clinically diagnosed hypogonadism, that’s a medical conversation. Ashwagandha is a peer-reviewed support for natural-range optimization, not a substitute for medical treatment.
How long until I see strength gains from ashwagandha?
The trial endpoint was 8 weeks. Subjective improvements (better sleep, less between-session soreness, more capacity for hard sets) often show up in 2–4 weeks.
Should I cycle ashwagandha for strength?
The trials don’t cycle. The 2025 12-month safety study found sustained efficacy without decline. Some athletes cycle 8 on / 2 off as precaution; the literature doesn’t require it.
The bottom line
The strength evidence on ashwagandha is real, well-designed, and replicable at the right dose — 600mg/day KSM-66®, daily, for at least 8 weeks. The effect compounds with training rather than replacing it. Optibio® Ashwagandha KSM-66® matches the trial protocol.†
Related: ashwagandha muscle recovery, best ashwagandha for endurance, KSM-66 benefits for men, our science page.
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†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.