Caffeine gum improves reaction time but reduces composure versus placebo during the extra-time period of simulated soccer match-play in male semi-professional players
This study aimed to determine whether caffeine gum influenced perceptual-cognitive and physical performance during the extra-time period of simulated soccer match-play. Semi-professional male soccer players (n=12, age: 22 ± 3 years, stature: 1.78 ± 0.06 m, mass: 75 ± 9 kg) performed 120-min soccer specific exercise on two occasions. In a triple blind, randomised, crossover design, players chewed caffeinated (200-mg; caffeine) or control (0-mg; placebo) gum for 5-min following 90-min of soccer specific exercise. Perceptual-cognitive skills (i.e., passing accuracy, reaction time, composure, adaptability) were assessed using a soccer specific virtual reality simulator, collected pre- and post-trial. Neuromuscular performance (reactive-strength index, vertical jump height, absolute and relative peak power output, and negative vertical displacement) and sprint performance (15- and 30-m) were measured at pre-trial, half-time, 90-min and post-trial. Caffeine gum attenuated declines in reaction time (pre: 90.8 ± 0.8 AU to post: 90.7 ± 0.8 AU) by a further 4.2% than placebo (pre: 92.1 ± 0.8 AU to post: 88.2 ± 0.8 AU; p <0.01). Caffeine gum reduced composure by 4.7% (pre: 69.1 ± 0.8 AU to post: 65.9 ± 0.8 AU) versus placebo (pre: 68.8 ± 0.8 AU to post: 68.3 ± 0.8 AU; p <0.01). Caffeine gum did not influence any other variables (p >0.05). Where caffeine gum is consumed by players prior to extra-time, reaction time increases but composure may be compromised, and neuromuscular and sprint performance remain unchanged. Future work should assess caffeine gum mixes with substances like L-theanine that promote a relaxed state under stressful conditions
