Effects of Ashwagandha ( Withania somnifera) standardized root extract on physical endurance and VO 2max in healthy adults performing resistance training: An eight-week, prospective, randomized, double-blind, placebo-controlled study – PubMed Black Hawk Supplements

Background: Ashwagandha is a well-known Ayurvedic herb used for youthful vigor and wellbeing. This study investigated the effects of 600 mg standardized root extract (>5% withanolides) of Ashwagandha ( Withania somnifera) on muscle size, strength and cardiorespiratory endurance following resistance training.

Methods: In this eight-week, parallel-group, multicenter, randomized, double-blind, placebo-controlled clinical study, 80 healthy male and female participants aged 18-45 years, who engaged in regular physical activity were randomly allocated in a 1:1 ratio to receive Ashwagandha (AG, n=40) 300 mg capsules twice daily for eight weeks, or identical placebo (PB, n=40). Seven (3 AG, 4 PB) participants were excluded due to poor compliance. All participants conducted eight-week resistance training. Study outcomes included muscle strength (1RM bench press and leg extension), muscle size (circumference of arm, chest and upper thigh) and cardio-respiratory endurance (VO _2max) assessed at baseline and at eight weeks. Analysis of covariance (ANCOVA) was used to estimate adjusted differences based on sex, BMI and chest circumference at baseline.

Results: AG caused greater improvement in bench press (males: p = 0.0084; females: p = 0.0005), leg press (males: p = 0.0049; females: p = 0.018) and endurance (males: p <0.0001; females: p <0.0001) as compared to PB. Also, greater improvements in muscle girth for arm, chest and thigh were seen in both male and female participants with AG. No adverse events were reported in the study.

Conclusions: Eight weeks of AG root extract supplementation along with resistance training is effective in improving muscle strength, growth and endurance in both male and female participants. AG root extract could be a safer, effective and low-cost alternative for athletes to improve muscle endurance.

1. 1. Lloyd RS, Faigenbaum AD, Stone MH, et al. : Position statement on youth resistance training: the 2014 International Consensus. Br J Sports Med. 2014 Apr;48(7):498–505. 10.1136/bjsports-2013-092952 – DOI – PubMed
2. 1. Kraemer WJ, Ratamess NA: Fundamentals of Resistance Training: Progression and Exercise Prescription. Med Sci Sport Exerc. 2004 Apr;36(4):674–688. 10.1249/01.MSS.0000121945.36635.61 Reference Source – DOI – PubMed
3. 1. Staron RS, Karapondo DL, Kraemer WJ, et al. : Skeletal muscle adaptations during early phase of heavy-resistance training in men and women. J Appl Physiol. 1994 Mar 1;76(3):1247–1255. 10.1152/jappl.1994.76.3.1247 – DOI – PubMed
4. 1. Sale DG: Neural adaptation to resistance training. Med Sci Sport Exerc. 1988 Oct;20(Sup 1):S135–S145. 10.1249/00005768-198810001-00009 Reference Source – DOI – PubMed
5. 1. Nieman DC, Wentz LM: The compelling link between physical activity and the body’s defense system. J Sport Heal Sci. 2019 May;8(3):201–217. 10.1016/j.jshs.2018.09.009 Reference Source – DOI – PMC – PubMed