Didn't know this....
Even though Ashwagandha is good , this may be a better bet. Both Ashwagandha and Siberian Ginseng have CNS sedative effects (yes , they calm you because they are depressants...) Siberian Ginseng has some data which shows may can increase athletic performance
Evidence
Siberian ginseng is traditionally used to enhance how your body handles mental and physical stress, and researchers believe the adaptogenic properties of this herb increases your ability to adapt to internal and external stressers, such as vigorous exercise. While Siberian ginseng does not seem to directly promote muscle growth, its stimulating qualities have shown promise in prolonging exercise time, according to studies cited by NutritionalReviews.org. By extending the amount of time before your body reaches fatigue, you may be able to increase muscle growth by increasing training duration. Further research is required to uncover Siberian ginseng's true value for muscle growth and exercise longevity.
Read more:
Does Siberian Ginseng Promote Muscle Growth? | LIVESTRONG.COM