Touted as an exercise enhancer, caffeine works only if you’re not a java junkie. A study in the International Journal of Sport Nutrition and Exercise Metabolism found that guys who chewed caffeinated gum while running sprint drills had delayed muscle fatigue if they were low caffeine users (consuming the equivalent of a cup of coffee a day or less).
“Repeated exposure to caffeine reduces a person’s sensitivity to its effects,” says Brendan Egan of Dublin City University. If you’re a coffee fiend, gradually taper consumption in the four days leading up to a sporting event, then drink your usual amount the morning of.
