Acute caffeine mouth rinse does not improve performance in recreationally trained runners: a pilot study

Abstract

The purpose of this study was to investigate if acute caffeine mouth rinse improved 800-m running time-trial performance compared with placebo in recreational runners. In a randomized, crossover, double-blind, and placebo-controlled study, seven recreationally endurance-trained men (age 24.6 ± 11.5 years; body mass 78.2 ± 7.9 kg) performed an 800-m running time-trial on two main occasions. Prior to running, participants received 50 mL of water plus 300 mg of anhydrous caffeine (0.6% caffeine solution) or placebo (microcrystalline cellulose) for mouth rinsing during a 10-s exposure. Blood samples were collected pre- and post-run for analysis of glycemia and lactate. Caffeine mouth rinse had no significant effect on time-trial performance (placebo: 185.6 ± 30.3 vs. caffeine: 189.6 ± 30.4 s, p = 0.405, effect size: 0.13), glycemia (placebo group, pre: 88.6 ± 12.4 and post: 100.4 ± 17.9 mg/dL vs. caffeine group, pre: 80.3 ± 10.4 and post: 79.1 ± 15.4 mg/dL), or blood lactate (placebo group, pre: 1.0 ± 0.8 and post: 9.0 ± 4.2 vs. caffeine group, pre: 1.2 ± 0.9 and post: 7.0 ± 4.3 mmol/L) compared to placebo, although blood lactate (placebo group p = 0.0001 and caffeine group p = 0.002) was increased from pre- to post-exercise. A moderate dose caffeine mouth rinse given just prior to exercise does not improve 800-m running time-trial performance in recreationally trained runners.