Ashwagandha Clinical Studies Muscle Mass: A Scientific Review

⏱ 12 min read

By Kóre Labs Team | Published: March 19, 2026

Curious about Ashwagandha clinical studies and muscle mass? You're in the right place. Scientific research suggests that Ashwagandha (Withania somnifera), a powerful adaptogen, may indeed support muscle growth, strength increase, and improved recovery when paired with resistance training. Studies indicate potential mechanisms involving cortisol reduction and optimized hormonal balance. This article delves into the clinical evidence, exploring how this ancient herb might enhance your physical performance and body composition goals. Read on to uncover the science behind Ashwagandha's potential for muscle support.

Key Takeaways

• Clinical studies suggest Ashwagandha may increase muscle mass and strength when combined with resistance training.
• Potential mechanisms include reducing cortisol (a catabolic hormone) and supporting healthy testosterone levels.
• Research indicates improvements in exercise recovery and reduced exercise-induced muscle damage.
• Dosages in effective studies typically range from 300mg to 1250mg of standardized extract daily.
• Ashwagandha is generally considered safe, but consulting a healthcare professional is advised.

What Does Science Say About Ashwagandha and Muscle Mass?

According to multiple clinical studies, Ashwagandha shows promise in supporting muscle mass increases, especially when individuals engage in regular resistance training. Research suggests this adaptogen may enhance the body's adaptation to exercise stimuli.

Several peer-reviewed, double-blind, placebo-controlled trials have investigated the impact of Ashwagandha supplementation on body composition and physical performance. One notable study published in the Journal of the International Society of Sports Nutrition (Wankhede et al., 2015) examined the effects of 300 mg of Ashwagandha root extract taken twice daily for eight weeks in healthy young men engaged in resistance training. The results were compelling: the Ashwagandha group experienced significantly greater increases in muscle strength (measured by bench press and leg extension) and muscle size (measured in the arms and chest) compared to the placebo group. Furthermore, the Ashwagandha group showed a significantly greater reduction in exercise-induced muscle damage, as indicated by lower serum creatine kinase levels.

Another study, published in Nutrients (Ziegenfuss et al., 2018), corroborated these findings. This trial involved healthy recreationally active men and women who took either a placebo or 500 mg of a standardized Ashwagandha extract daily for 12 weeks while participating in a structured resistance training program. The Ashwagandha group demonstrated significantly greater improvements in maximal strength (1-RM squat and bench press) and average power output compared to the placebo group. Increases in muscle thickness were also observed, further supporting the potential of Ashwagandha to enhance muscle mass accretion in conjunction with training.

While these studies provide encouraging evidence, it's crucial to acknowledge the nuances. The effectiveness of Ashwagandha may vary based on factors like age, training status, dosage, and the specific extract used. Moreover, the exact mechanisms are still being elucidated, although hypotheses center on hormonal modulation and stress reduction.

For those interested in optimizing their training and recovery, exploring supplements for physical performance like Ashwagandha, potentially alongside other proven ingredients such as Creatine Monohydrate, could be a worthwhile consideration, always informed by scientific understanding.

Clinical Evidence: Ashwagandha's Impact on Muscle Strength

Clinical evidence strongly suggests that Ashwagandha supplementation can lead to significant improvements in muscle strength. Multiple studies have demonstrated increased 1-RM (one-repetition maximum) loads in key exercises like bench press and squats among participants taking Ashwagandha compared to those on a placebo.

The ability of Ashwagandha to enhance muscle strength is a recurring theme in clinical research. The Wankhede et al. (2015) study mentioned earlier reported that participants taking 600 mg of Ashwagandha root extract daily for eight weeks achieved significantly greater increases in their 1-RM bench press (46.0 kg vs. 26.4 kg for placebo) and leg extension (14.5 kg vs. 9.8 kg for placebo). These substantial differences highlight the potential of Ashwagandha to amplify strength gains from resistance training.

Similarly, the study by Ziegenfuss et al. (2018) found that 12 weeks of supplementation with 500 mg of Ashwagandha extract resulted in significantly greater improvements in maximal squat strength (mean increase of 19.1 kg vs. 10.1 kg for placebo) and bench press strength (mean increase of 11.2 kg vs. 5.9 kg for placebo). The consistency of these findings across different studies and standardized extracts strengthens the evidence supporting Ashwagandha's efficacy in enhancing muscle strength.

Beyond maximal strength, some research also hints at improvements in muscle endurance and power output. For instance, a study published in the International Journal of Ayurveda Research (Raut et al., 2012) observed increases in handgrip strength and quadriceps strength in healthy volunteers taking Ashwagandha, although this study was not specifically focused on resistance-trained individuals. Another study (Sandhu et al., 2010) reported improvements in maximum velocity and average power in healthy young adults after Ashwagandha supplementation.

These findings collectively suggest that Ashwagandha may be a valuable tool for individuals seeking to maximize their strength gains. However, it's important to remember that supplementation is not a substitute for consistent, well-structured training. For comprehensive athletic support, formulas like Essential Marathon, which combine multiple performance-enhancing ingredients, might also be considered, depending on individual goals.

Mechanisms of Action: How Ashwagandha Might Work

The mechanisms behind Ashwagandha's effects on muscle mass and strength likely involve its adaptogenic properties, specifically its ability to reduce cortisol levels and potentially support healthy testosterone levels. Reduced stress and optimized hormonal balance create a more favorable environment for muscle protein synthesis and recovery.

One of the primary ways Ashwagandha is thought to exert its effects is through the modulation of the hypothalamic-pituitary-adrenal (HPA) axis, the body's primary stress response system. Chronic stress leads to elevated levels of cortisol, a catabolic hormone that can promote muscle breakdown and inhibit muscle protein synthesis. As an adaptogen, Ashwagandha has been shown in numerous clinical studies to significantly lower serum cortisol levels in stressed individuals. By reducing cortisol, Ashwagandha may help shift the body's hormonal balance from a catabolic (breakdown) state to a more anabolic (building) state, which is conducive to muscle growth and repair.

Furthermore, some research suggests that Ashwagandha may support healthy testosterone levels, particularly in men. Testosterone is a key anabolic hormone crucial for muscle mass accretion and strength development. A study by Ambiye et al. (2013) found that Ashwagandha root extract supplementation resulted in a significant increase in serum testosterone levels in oligospermic males. While studies in healthy, resistance-trained men have shown mixed results regarding testosterone increases (Wankhede et al., 2015 reported an increase, while Ziegenfuss et al., 2018 did not observe a significant change), the potential for testosterone support, especially in individuals with lower baseline levels or under high stress, remains an intriguing mechanism.

In addition to hormonal modulation, Ashwagandha may also contribute to muscle gains by improving exercise recovery. The reduced levels of creatine kinase observed in the Wankhede et al. (2015) study suggest less muscle damage following exercise. Faster recovery allows for more frequent or intense training sessions, ultimately leading to greater adaptations over time. The potential anti-inflammatory and antioxidant properties of Ashwagandha's bioactive compounds, such as withanolides, may also play a role in mitigating exercise-induced muscle damage and inflammation.

While these mechanisms are plausible and supported by some evidence, further research is needed to fully understand the intricate pathways through which Ashwagandha influences muscle physiology. For a deeper dive into hormonal health, you might find our article on adaptogens for hormonal balance insightful.

Dosage and Timing: Optimizing Ashwagandha for Muscle Support

Based on clinical studies, effective dosages of Ashwagandha for supporting muscle mass and strength typically range from 300 mg to 1250 mg of standardized root extract per day. The most common protocol involves splitting the total daily amount into two doses, often taken in the morning and evening.

Determining the optimal Ashwagandha dosage requires looking at the specific extracts and protocols used in successful clinical trials. Studies demonstrating significant benefits often utilize standardized extracts, such as KSM-66® or Shoden®, which guarantee a certain percentage of active withanolides.

• The Wankhede et al. (2015) study, which showed substantial strength and size gains, used 300 mg of KSM-66® Ashwagandha root extract twice daily (totaling 600 mg/day).
• The Ziegenfuss et al. (2018) study utilized 500 mg of another standardized Ashwagandha extract daily.
• Other studies investigating stress and anxiety, which indirectly impact muscle health through cortisol reduction, have used dosages ranging from 300 mg to 600 mg daily.

Regarding timing, most studies administer Ashwagandha doses with meals. Splitting the dose (e.g., morning and evening) may help maintain more stable levels of the active compounds in the body throughout the day. While some people prefer taking Ashwagandha before workouts due to its potential energy-boosting effects (perhaps linked to improved mitochondrial function, though more research is needed), or before bed due to its potential sleep-promoting qualities, the primary goal for muscle support seems to be consistent daily intake rather than specific nutrient timing relative to exercise.

It's important to note that more is not necessarily better. Higher dosages (up to 1250 mg/day) have been used in some studies and appear to be well-tolerated, but the incremental benefit for muscle growth beyond the 500-600 mg range is not clearly established. As with any supplement, starting with a lower dose and monitoring your body's response is a sensible approach. Consistency over weeks and months is key, as the adaptogenic effects of Ashwagandha typically build over time.

Safety and Considerations for Ashwagandha Supplementation

Ashwagandha is generally considered safe and well-tolerated when used appropriately, as evidenced by numerous clinical trials. However, potential side effects can occur, and certain individuals should exercise caution or avoid supplementation. Always consult a healthcare professional before adding Ashwagandha to your regimen.

In clinical studies, reported side effects of Ashwagandha are typically mild and infrequent. Some individuals may experience gastrointestinal upset, such as diarrhea, nausea, or stomach pain, particularly with higher doses. Drowsiness or sedation is another potential effect, given Ashwagandha's traditional use as a calming herb; this might be beneficial for sleep but potentially undesirable during the day for some.

Despite its general safety profile, there are important contraindications for Ashwagandha:

• Pregnancy and Breastfeeding: Ashwagandha should be avoided during pregnancy as it may have abortifacient effects. There is insufficient safety data regarding its use during breastfeeding.
• Autoimmune Diseases: Due to its potential immune-modulating effects, Ashwagandha might exacerbate symptoms in individuals with autoimmune conditions like multiple sclerosis, lupus, rheumatoid arthritis, or Hashimoto's thyroiditis. Consult a doctor before use.
• Thyroid Conditions: Ashwagandha may increase thyroid hormone levels. Individuals with hyperthyroidism or those taking thyroid medication should monitor their thyroid function closely if using Ashwagandha and do so only under medical supervision.
• Surgery: Ashwagandha may have sedative effects and could interact with anesthesia. It is generally recommended to stop taking it at least two weeks before scheduled surgery.
• Medication Interactions: Ashwagandha may interact with certain medications, including sedatives (due to potential additive effects), thyroid hormones, immunosuppressants, and medications for diabetes or high blood pressure.

Quality control is also a crucial consideration. Ensure you choose supplements from reputable brands that use standardized extracts and undergo third-party testing to verify purity and potency, avoiding potential contaminants or adulterants. For more guidance on selecting high-quality supplements, check out our article on how to evaluate supplement quality.

Conclusion

In conclusion, the body of scientific evidence from Ashwagandha clinical studies regarding muscle mass is promising. Multiple well-designed trials suggest that supplementation, particularly with standardized root extracts in the range of 500-600 mg daily, can significantly enhance muscle strength and size when combined with resistance training. The likely mechanisms involve reducing cortisol levels, supporting an optimal anabolic environment, and improving exercise recovery. While Ashwagandha is generally safe, it's essential to be aware of potential side effects and contraindications, especially for individuals with specific health conditions or taking medications. As with any supplement, consulting a healthcare professional is paramount. For those seeking evidence-based ways to support their physical performance and body composition goals, Ashwagandha presents a compelling, science-backed option worth exploring within a comprehensive training and nutrition strategy.

Ready to experience the science-backed benefits of premium Ashwagandha? Discover Kóre Labs' standardized Ashwagandha extract and support your muscle-building journey today. Your rebirth begins now.

References

1. Ambiye, V. R., et al. (2013). Clinical Evaluation of the Spermatogenic Activity of the Root Extract of Withania somnifera (Ashwagandha) in Oligospermic Males: A Pilot Study. Evidence-Based Complementary and Alternative Medicine. doi: 10.1155/2013/571420
2. Raut, A. A., et al. (2012). Exploratory study to evaluate tolerability, safety, and activity of Ashwagandha (Withania somnifera) in healthy volunteers. International Journal of Ayurveda Research. doi: 10.4103/0974-7788.100435
3. Sandhu, J. S., et al. (2010). Effects of Withania somnifera (Ashwagandha) and Terminalia arjuna (Arjuna) on physical performance and cardiorespiratory endurance in healthy young adults. International Journal of Ayurveda Research. doi: 10.4103/0974-7788.72485
4. Wankhede, S., et al. (2015). Examining the effect of Withania somnifera supplementation on muscle strength and recovery: a randomized controlled trial. Journal of the International Society of Sports Nutrition. doi: 10.1186/s12970-015-0104-9
5. Ziegenfuss, T. N., et al. (2018). Effects of an Aqueous Extract of Withania somnifera on Strength Training Adaptations and Recovery: The STAR Trial. Nutrients. doi: 10.3390/nu10111807