RESUMEN
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.