Carbohydrate Mouth Rinse Maintains Muscle Electromyographic Activity and Increases Time to Exhaustion during Moderate but not High-Intensity Cycling Exercise

Abstract

The aim was to investigate the influence of a carbohydrate (CHO) mouth rinse on the vastus lateralis (VL) and rectus femoris (RF) electromyographic activity (EMG) and time to exhaustion (TE) during moderate (MIE) and high-intensity cycling exercise (HIE). Thirteen participants cycled at 80% of their respiratory compensation point and at 110% of their peak power output to the point of exhaustion. Before the trials and every 15 min during MIE, participants rinsed with the CHO or Placebo (PLA) solutions. The root mean square was calculated. CHO had no effect on the TE during HIE (CHO: 177.3 ± 42.2 s; PLA: 163.0 ± 26.7 s, p = 0.10), but the TE was increased during MIE (CHO: 76.6 ± 19.7 min; PLA: 65.4 ± 15.2 min; p = 0.01). The EMG activity in the VL was higher than PLA at 30 min (CHO: 10.5% ± 2.6%; PLA: 7.7% ± 3.3%; p = 0.01) and before exhaustion (CHO: 10.3% ± 2.5%; PLA: 8.0% ± 2.9%; p = 0.01) with CHO rinsing. There was no CHO effect on the EMG activity of RF during MIE or for VL and RF during HIE. CHO mouth rinse maintains EMG activity and enhances performance for MIE but not for HIE.

Carbohydrate mouth rinse reduces rating of perceived exertion but does not affect performance and energy systems contribution during a high-intensity exercise

“…Nevertheless, even without significant difference, time to exhaustion was 4.4% longer in CHO than in PLA, and was associated with a lower RPE, possibly because CHO mouth rinse may have activated brain regions (including areas of the insula/frontal operculum, orbitofrontal cortex and striatum) involved in reward 8,9 . This result corroborates recent findings 28 showing that even with a reduced RPE at the exhaustion after CHO mouth rinse, exercise endurance at 110% of PPO was not altered after a CHO mouth rinse. It was showed that CHO rinsing is able to maintain neuromuscular activation (i.e., the electromyographic signal of the vastus lateralis) along of time during moderate-, but not high-intensity exercise 28 .…”

“…This result corroborates recent findings 28 showing that even with a reduced RPE at the exhaustion after CHO mouth rinse, exercise endurance at 110% of PPO was not altered after a CHO mouth rinse. It was showed that CHO rinsing is able to maintain neuromuscular activation (i.e., the electromyographic signal of the vastus lateralis) along of time during moderate-, but not high-intensity exercise 28 . Probably, an activation of reward areas with CHO rinse is able to reduce feelings of fatigue during the high-intensity exercise, but it is not sufficient to translate in an improvement in the exercise performance in this kind of exercise.…”

Cycling time trial performance is improved by carbohydrate ingestion during exercise regardless of a fed or fasted state

“…The presence of carbohydrate in the mouth stimulates a group of sensory receptors that activates some areas of the brain that are associated with reward and motor control, 25 ultimately reducing RPE. 27 Interestingly, this central effect of carbohydrate supplementation during exercise seems to be more pronounced when endogenous carbohydrate availability is low. 28 Therefore, it seems reasonable to assume that any central effect of carbohydrate ingestion during exercise would become more important as the exercise progresses and endogenous carbohydrate availability decreases.…”

Efeitos do bochecho com carboidrato sobre o desempenho físico, respostas cerebrais e psicofisiológicas de ciclistas mentalmente fadigados durante um teste incremental máximo

“…2) Utilizamos um TIM para testar as intervenções propostas, pois ambas as manipulações realizadas no presente estudo (i.e. FM e bochecho com CHO) respondem diferentemente de acordo com a intensidade do exercício (BASTOS-SILVA et al, 2016;DUNCAN et al, 2015).…”

“…Tem sido proposto que o modelo de FM esteja ligado a alterações ocorridas no sistema nervoso central, principalmente em regiões corticais como córtex pré-frontal (CPF), córtex orbitofrontal e córtex cingulado anterior, as quais seriam possivelmente mediadas pela ação de , um efeito possivelmente associado à ativação dessas regiões cerebrais.Além disso, é possível que o bochecho com CHO tenha diferentes efeitos quando utilizado em exercício de diferentes intensidades(BASTOS-SILVA et al, 2016). Por exemplo,Bastos investigaram o efeito do bochecho com CHO sobre testes até a exaustão em diferentes intensidades.…”