Carbohydrate mouth rinse enhances time to exhaustion during treadmill exercise

Abstract

Mouth rinsing with a CHO solution has been suggested to improve short (<1 h) endurance performance through central effect. We examined the effects of mouth rinsing with a CHO solution on running time to exhaustion on a treadmill. Six well-trained subjects ran to exhaustion at 85% VO , on three separate occasions. Subjects received either an 8% CHO solution or a placebo (PLA) every 15 min to mouth rinse (MR) or a 6% CHO solution to ingest (ING). Treatments were assigned in a randomized, counterbalanced fashion, with the mouth-rinsing treatments double-blinded. Blood samples were taken to assess glucose (Glu) and lactate (Lac), as well as the perceived exertion (RPE). Gas exchange and heart rate (HR) were collected during all trials. Subjects ran longer (P = 0·038) in both the MR (2583 ± 686 s) and ING (2625 ± 804 s) trials, compared to PLA (1935 ± 809 s), covering a greater distance (MR 9685 ± 3511·62 m; ING 9855 ± 4118·62; PLA 7295 ± 3727 m). RER was significantly higher in both ING and MR versus PLA. No difference among trials was observed for other metabolic or cardiovascular variables (VO , Lac, Glu, HR), nor for RPE. Endurance capacity, based on time to exhaustion on a treadmill, was improved when either mouth rinsing or ingesting a CHO solution, compared to PLA.

Carbohydrate Mouth Rinse Fails to Improve Four-Kilometer Cycling Time Trial Performance

“…Similarly, pacing strategy did not differ between conditions (i.e., CHO mouth rinse and PLA) throughout the trial. Despite several studies [ 1 , 3 , 24 ] showing that CHO mouth rinse is effective to improve cycling performance, our results corroborate those of others showing no benefits in using this strategy [ 7 , 9 , 25 , 26 ]. Some aspects could be highlighted to discuss this controversy.…”

“…Although some studies have shown benefits of CHO mouth rinse on performance in both fed and fasted states [ 2 , 31 ], some showed improvements only if participants commenced the exercise in a fasted state (>4 h fasting) [ 3 , 24 ] and others failed to show improvements with CHO mouth rinse in a fed state [ 25 , 26 ], thereby leading to inconclusive interpretations about the influence of the pre-exercise fasting period. There is a questionable applicability of this intervention in real-world situations, as athletes (recreational or professional) usually avoid to train and compete in a fasting state.…”

Cognitive Performance Enhancement Induced by Caffeine, Carbohydrate and Guarana Mouth Rinsing during Submaximal Exercise

“…This result is very interesting since results are mixed and most studies have failed to observe benefits from CHO MR [9,44,75,76,77] and CAF MR [18,78] on perception of effort. Only a few studies have reported that CAF and CHO MR could lead to a decrease in RPE [25,26,27] suggesting that CHO and CAF MR induce a decrease in subjective perception of effort, allowing participants to produce more power with the same degree of discomfort.…”

A randomized controlled trial of nitrate supplementation in well-trained middle and older-aged adults

“…Open-ended test where subjects are required to exercise at a constant work rate for as long as possible have been criticized due to the greater variation in performance time versus closed-end tests where subjects are required to cover a given distance in the quickest time possible or ride for a given time period and told to complete the greatest distance possible [47]. However, it should be noted that not all studies using open-ended tests have reported large variations in exercise time [48], and studies have reported differences in exercise time when evaluating the effects of other nutritional supplements [49].…”