Failure training is a popular technique for creating a level of physical stress that can lead to muscle size and strength gains. So what's a good pre-workout shot of caffeine have to offer those who are determined to take their workouts further? A study published in The Journal of Sports Medicine and Physical Fitness analyzed the effects of 5 mg of caffeine per kg of body weight on moderately trained men.
Subjects consumed a caffeinated beverage or a placebo 60 minutes before weight training. Performance was rated by counting the number of repetitions each subject was able to perform and asking them to rate the level of perceived exertion. The caffeinated lifters were able to get in more reps while experiencing less pain compared to subjects who received a placebo instead of caffeine. For a 150 pound guy, the total amount of caffeine consumed an hour before training would have been 340 mg.