No Improvement in Running Time to Exhaustion at 100% VO 2 max in Recreationally Active Male Runners With a Preexercise Single-Carbohydrate Mouth Rinse.

BACKGROUND:: Carbohydrate (CHO) mouth rinse has been used as an ergogenic strategy due to its central effect; however, the effects of this intervention in short and high-intensity exercises are not fully understood.

PURPOSE:: We aimed to investigate the effect of CHO mouth rinse on time to exhaustion in a short and high-intensity exercise performed on a treadmill.

METHODS:: A randomized double-blind, placebo-controlled, and crossover study was conducted with 10 (24.1±4.3 years) recreationally active male runners. The protocol consisted of a warm-up at 65% of VO2max for 5 min followed with 3 min passive rest. At the end of this rest period, the individuals performed their mouth rinse either with CHO (maltodextrin, 6%) or placebo (PLA) (industrialized non-caloric juice with the same taste). Immediately after mouth rinse, the subjects ran at velocity equivalent to 100% of individual's VO2max until voluntary exhaustion. The perceived effort was obtained through Borg scale. Blood lactate was quantified before and after the protocol, and heart rate was evaluated during the protocol.

RESULTS:: No difference was found (p=0.898) in time to exhaustion between PLA (193.9 ± 46.5 seconds) and CHO mouth rinse (195.1 ± 51.8 seconds). Blood lactate, heart rate and perception of effort increased in both groups, but with no differences (all variables, p > 0.05) between groups.

CONCLUSIONS:: The present study findings showed that a single pre-exercise CHO mouth rinse was ineffective to improve running time to exhaustion at velocity equivalent to 100% VO2max on a treadmill in recreationally active male runners.