Effects of Caffeinated Gum on a Battery of Soccer-Specific Tests in Trained University-Standard Male Soccer Players

The purpose of this study was to determine whether caffeinated gum influenced performance in a battery of soccer-specific tests used in the assessment of performance in soccer players. In a double-blind, randomized, crossover design, 10 male university-standard soccer players (age: 19 +/- 1 years, stature: 1.80 +/- 0.10 m, body mass: 75.5 +/- 4.8 kg) masticated a caffeinated (200 mg; caffeine) or control (0 mg; placebo) gum on two separate occasions. After a standardized warm-up, gum was chewed for 5 min and subsequently expectorated 5 min before players performed a maximal countermovement jump, a 20-m sprint test, and the Yo-Yo Intermittent Recovery Test Level 1. Performance on 20-m sprints was not different between trials (caffeine: 3.2 +/- 0.3 s, placebo: 3.1 +/- 0.3 s; p = .567; small effect size: d = 0.33), but caffeine did allow players to cover 2.0% more distance during Yo-Yo Intermittent Recovery Test Level 1 (caffeine: 1,754 +/- 156 m, placebo: 1,719 +/- 139 m; p = .016; small effect size: d= 0.24) and increase maximal countermovement jump height by 2.2% (caffeine: 47.1 +/- 3.4 cm, placebo: 46.1 +/- 3.2 cm; p = .008; small effect size: d= 0.30). Performance on selected physical tests (Yo-Yo Intermittent Recovery Test Level 1 and countermovement jump) was improved by the chewing of caffeinated gum in the immediate period before testing in university-standard soccer players, but the sizes of such effects were small. Such findings may have implications for the recommendations made to soccer players about to engage with subsequent exercise performance.