Caffeine is one of the most popular sports supplements, and for good reason. Caffeine has been shown to improve muscle fatigueability, endurance performance, and may even increase pain tolerance. Try 3-6mg/kg bodyweight within an hour before your workout. Make sure to maintain hydration and electrolyte levels if supplementing with high amounts of caffeine.
Source: Graham, T. E. (2001). Caffeine and exercise. Sports Medicine, 31(11), 785-807.

From being a mediocre athlete, to professional powerlifter and strength coach, and now to researcher and writer, Charlie combines education and experience in the effort to help Bridge the Gap Between Science and Application. Charlie performs double duty by being the Content Manager for The Muscle PhD as well as the Director of Human Performance at the Applied Science and Performance Institute in Tampa, FL. To appease the nerds, Charlie is a PhD candidate in Human Performance with a master’s degree in Kinesiology and a bachelor’s degree in Exercise Science. For more alphabet soup, Charlie is also a Certified Strength and Conditioning Specialist (CSCS), an ACSM-certified Exercise Physiologist (ACSM-EP), and a USA Weightlifting-certified performance coach (USAW).