The physiological and performance effects of caffeine gum consumed during a simulated half-time by professional academy rugby union players

Despite the prevalence of caffeine as an ergogenic aid, few studies have examinedthe use of caffeinated gums, especially during half-time in team sports. Thephysiological (blood lactate, salivary hormone concentrations) and performance(repeated sprints, cognitive function) effects of consuming caffeine gum during asimulated half-time were examined. Professional academy rugby union players(n=14) completed this double-blind, randomized, counterbalanced study. Following pre-exercise measurements, players chewed a placebo (PL) gum for five min before a standardized warm-up and completing repeated sprint testing (RSSA1). Thereafter, during a 15 min simulated half-time period, players chewed either caffeine (CAF: 400 mg; 4.1 ± 0.5 mg·kg-1) or PL gum for five min before completing a second repeated sprint test (RSSA2). Blood lactate, salivary testosterone and cortisol concentrations, and indices of cognitive function (i.e., reaction time and Stroop test) were measured at baseline, pre-RSSA1, post-RSSA1, pre-RSSA2 and post-RSSA2. Sprint performance was not affected by CAF (P=0.995) despite slower sprint times following the first sprint of both RSSA tests (all P<0.002). Following halftime, salivary testosterone increased by 70% (+97±58 pg·mL-1) in CAF versus PLA (P<0.001) whereas salivary cortisol remained unchanged (P=0.307). Cognitive performance was unaffected by time and trial (all P>0.05). Although performance effects were absent, chewing caffeine gum increased the salivary testosterone concentrations of professional rugby union players over a simulated half-time. Practitioners may therefore choose to recommend caffeine gum between successive exercise bouts due to the increases in salivary testosterone observed; a variable associated with increased motivation and high-intensity exercise performance.