Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial

Randomized, double-blind, placebo-controlled parallel-group trial; 57 healthy young men (18–50 years) with little resistance-training experience; 29 assigned to ashwagandha, 28 to placebo; 50 completed (25 per group).

Ashwagandha root extract (KSM-66), 300 mg per capsule, two capsules daily (600 mg/day), after awakening and before bedtime, for 8 weeks.

Ashwagandha supplementation plus resistance training produced greater gains in muscle strength and size, improved body composition, higher testosterone, and faster recovery from exercise-induced muscle damage versus placebo after 8 weeks in healthy young men. Bench press 1-RM change: +46.05 kg (vs +26.42 kg with placebo; p<0.001); Leg extension 1-RM change: +14.50 kg (vs +9.77 kg; p=0.04). Arm size change: +8.89 cm2 (vs +5.30 cm2; p=0.01); Chest size change: +3.37 cm (vs +1.43 cm; p<0.001); Thigh size change not significant (p=0.36). Body fat percentage: decreased by 3.47% (Ashwagandha) vs 1.52% (placebo); p=0.03. Testosterone: +96.19 ng/dL vs approximately -3.47 ng/dL; between-group p=0.004. CK recovery: greater CK reduction from 24 h to 48 h in Ashwagandha (-1462.68 U/L) vs Placebo (-1307.48 U/L); p=0.03. Conclusion: Ashwagandha may be a useful adjunct to resistance training to enhance strength, body composition, testosterone, and recovery in this population.

Small sample size; 8-week duration; male-only and young; resistance-training novices; limited generalizability to women or older adults; potential training program confounds.