Caffeine could improve reaction times in sports even if fatigue arrives later in the game, reports Medicine in Science in Sports & Exercise. In the study, subjects took a caffeine pill with a dose equal to about one Venti Starbucks cup. One hour after consumption, they completed four 20-minute circuits that consisted of various movements needed in sports like soccer and football. While it may not sound like much, caffeine can also increase speed and make exercise seem less strenuous.