Effects of Different Doses of Caffeine on Anaerobic Exercise in Boys

This study investigated effects of low (1 mg.kg(-1)), moderate (3 mg.kg(-1)) and high (5 mg.kg(-1)) doses of caffeine on anaerobic performance in boys. Twenty-six 8- to 10-year-old boys participated in a double-blind, crossover, counter-balanced study. Boys received in random order a placebo (PL) or anhydrous caffeine: 1 (CAF-1), 3 (CAF-3), or 5 (CAF-5) mg caffeine.kg(-1) body mass in cherry flavored Sprite. Sixty minutes following consumption boys performed a static handgrip test and then a 30 s Wingate test. Maximal grip strength (21.5 +/- 4.9 & 21.6 +/- 4.7 vs. 20.4 +/- 4.0 kg) was significantly higher in CAF-5 & CAF-3 vs PL, respectively. Absolute and. relative peak power (287 +/- 72 vs 281 +/- 69 W & 8.0 +/- 0.9 vs 7.8 +/- 1.0 W.kg(-1)) were significantly higher in CAF-3 vs PL, respectively. Mean power (153 48 vs 146 43 W) was significantly higher in CAF-5 vs PL, respectively. Peak Wingate HR was significantly higher (189 +/- 8 vs 185 +/- 9 beats.min(-1)) in CAF-5 vs PL, respectively. These findings suggest that in boys CAF-1 did not affect performance. During the Wingate test CAF-3 resulted in higher peak power while CAF-5 increased mean power. The significant increase in peak HR following the Wingate test is likely related to greater mean power generated during CAF-5.