High-intensity interval training (HIIT) is an effective way to improve fitness rapidly. It is an unpleasant way to train, but it works. Caffeine, creatine monohydrate, and amino acids increase exercise performance and recovery from HIIT.
Jeffrey Stout and colleagues from the University of Oklahoma found that combining the three supplements (Game Time, Corr-Jensen Laboratories, Inc.) improved performance during three weeks of high-intensity interval training. Moderately-trained recreational athletes practiced HIIT three days a week for three weeks and took the supplement 30 minutes before each workout. The supplement might provide an edge that will help athletes better cope with high-intensity training. (Journal of the International Society of Sports Nutrition, 7:10)