Ashwagandha for Strength Training and Recovery: What the Evidence Really Shows
Ashwagandha (Withania somnifera) is one of the most-studied adaptogenic herbs in sports nutrition, marketed to athletes for its potential to blunt exercise-induced cortisol spikes, speed muscle recovery, and support strength gains. Two well-controlled bodies of evidence — a 2015 randomized trial in the Journal of the International Society of Sports Nutrition (JISSN) and a January 2026 randomized controlled trial published in Nutrients on team-sport athletes — give a clearer, more current picture of what ashwagandha can and cannot do.
What the strength-training research shows
In the JISSN trial, 57 healthy men with limited resistance-training experience took either 300 mg of standardized ashwagandha root extract (KSM-66) twice daily (600 mg/day total) or a placebo, alongside an 8-week structured resistance-training program. Compared with placebo, the ashwagandha group showed:
- Significantly greater increases in muscle strength on bench press and leg extension.
- Greater increases in muscle size at the arms and chest.
- Larger reductions in exercise-induced muscle damage markers (creatine kinase).
- Greater increases in testosterone and a larger drop in body fat percentage.
What the newest cortisol/recovery research shows
The 2026 Nutrients study followed 56 male and female team-sport athletes (rugby, water polo, football) during a demanding 42-day pre-season block, randomized to 600 mg/day of ashwagandha root extract or placebo. Rather than suppressing cortisol outright, the ashwagandha group's stress hormones stayed comparatively stable while placebo athletes showed significant rises in salivary cortisol (women) and cortisone (men) as training load accumulated. Ashwagandha-supplemented athletes also reported better recovery scores, less delayed-onset muscle soreness (DOMS), and lower perceived fatigue, and men in the ashwagandha group showed a significant improvement in countermovement jump (CMJ) performance — a marker of neuromuscular power.
Typical effective dose
Across the strongest trials, 300–600 mg/day of a standardized root extract (commonly KSM-66 or Sensoril, taken as 300 mg once or twice daily) is the dose range associated with measurable effects on strength, recovery, and stress hormones, generally over 6–8+ weeks of consistent use combined with a structured training program.
Evidence quality and limitations
- Sample sizes remain modest (well under 100 participants per trial), and most studies are funded or supplied by supplement manufacturers, which can introduce bias.
- Effects on cortisol appear more consistently as stabilization under stress rather than a large absolute reduction at rest; a 2025 systematic review found a significant cortisol-lowering effect but no consistent effect on perceived psychological stress.
- Strength and hypertrophy findings mostly come from novice or recreationally trained lifters — effects in advanced athletes are less established.
- Study durations are short (6–8 weeks); long-term (multi-month/year) data in athletes is limited.
Safety notes
Ashwagandha is generally well tolerated at studied doses, but it can stimulate thyroid hormone production and is not recommended without medical supervision for people with hyperthyroidism or thyroid-related conditions. Rare cases of liver-related issues have been reported in case literature, so anyone with liver disease, who is pregnant or breastfeeding, or who takes sedatives, thyroid medication, or immunosuppressants should consult a healthcare provider before use. As with any supplement, third-party tested products are preferable, and ashwagandha should complement — not replace — sleep, nutrition, and progressive training.
Helpful products
- KSM-66 Ashwagandha Extract Capsules — standardized root extract used in the clinical strength/recovery trials, typically dosed 300 mg twice daily.
- Sensoril Ashwagandha Supplement — alternative standardized extract studied for stress and cortisol modulation.
Source: Whitbread et al., Nutrients. "Ashwagandha Root Extract Stabilises Physiological Stress Responses in Male and Female Team Sports Athletes During Pre-Season Training". https://www.mdpi.com/2072-6643/18/2/230
