We frequently recommend caffeine as a preworkout supplement, because research tells us that caffeine can increase muscle strength and endurance (i.e., it allows you to work out harder for longer), as well as help you burn more bodyfat during the workout. Another study, this one from India, supports our recommendation. The Indian researchers had subjects consume either 0, 2, 4 or 6 milligrams of caffeine per pound of bodyweight (about 0 mg, 400 mg, 800 mg, or 1,200 mg of caffeine for a 200-pound bodybuilder) one hour before they tested their isometric muscle strength and isometric muscle endurance. The results showed that muscle strength increased with increasing doses of caffeine. The 2-mg dose boosted strength by 15%, the 4-mg dose by 40%, and the 6-mg dose by 50%. The researchers also found that muscle endurance increased following the same pattern. The 2-mg dose of caffeine provoked a 20% increase in endurance, the 4-mg dose increased muscle endurance by 40%, and the 6-mg dose boosted it by 50%. Take 200-400 mg of caffeine about one hour before workouts. When you’re planning a truly grueling workout or want to significantly boost strength, consider bumping up your caffeine intake to about 800 mg. But beware: you can develop a tolerance to caffeine, so to ensure that you can use this technique again, raise your caffeine consumption that high only occasionally.