Caffeine Mouth Rinse Does Not Improve Time to Exhaustion in Male Trained Cyclists

This study investigated the effects of caffeine mouth rinse on cycling time to exhaustion (TTE) and physiological responses in trained cyclists. In a double-blinded randomized counterbalanced cross-over design, 10 recreationally trained male cyclists (mean ± SD: 32 ± 3 years, 72.8 ± 5.3 kg, 1.78 ± 0.06 m, 13.9% ± 3.3% body fat, peak power output = 289.4 ± 24.7 W) completed two TTE tests cycling at 75% of peak aerobic power following 24 hr of dietary and exercise standardization. Cyclists were administered 25-ml mouth rinses for 5 s containing either 85 mg of caffeine or control (water) every 5 min throughout the exercise tests. No significant improvement in TTE was shown with caffeine mouth rinse compared with control (33:24 ± 12:47 vs. 28:08 ± 10:18 min; Cohen's dz effect size: 0.51, p = .14). Caffeine mouth rinse had no significant effect on ratings of perceived exertion (p = .31) or heart rate (p = .35) throughout the cycling TTE protocol. These data indicate that a repeated dose of caffeinated mouth rinse for 5 s does not improve cycling TTE in recreationally trained male cyclists. However, these findings should be taken with caution due to the small sample size and blinding ineffectiveness, while further well-design studies with larger samples are warranted.