Caffeine mouth rinse enhances performance, fatigue tolerance and reduces muscle activity during moderate-intensity cycling.

We investigated the effects of caffeine mouth rinse on endurance performance, muscle recruitment (i.e., electromyographic activity of the vastus lateralis and rectus femoris), rating of perceived effort and heart rate. Twelve physically-active healthy men cycled at 80% of their respiratory compensation point until task failure. The participants rinsed their mouths for 10 seconds with placebo (PLA, 25 mL of a solution composed of non-caloric mint essence) or caffeine (CAF, 25 mL of 1.2% of anhydrous caffeine concentration with non-caloric mint essence) every 15 minutes of exercise. Time until exhaustion increased 17% (effect size = 0.70) in CAF compared to PLA (p = 0.04). The wavebands of low-frequency electromyographic activity (EMG) of the vastus lateralis and rectus femoris was lower in CAF group than PLA at 50% of the time until exhaustion (p = 0.04). The global EMG signal was lower in CAF group than PLA at 100% of the time until exhaustion (p = 0.001). The rating of perceived effort pooled was higher in CAF mouth rinse (p = 0.001) than PLA group. No effect was found on the heart rate between the groups (p > 0.05). Caffeine mouth rinse increases endurance performance, rating of perceived effort and decreases muscle activity during a moderate-intensity exercise.

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

Aim: The study aimed to verify the effect of carbohydrate (CHO) mouth rinse on time to exhaustion, energy systems contribution and rating of perceived exertion (RPE) during a high-intensity exercise. Methods Fourteen men performed an incremental exercise test to determine their maximal oxygen uptake and peak power output (PPO) and two time-to-exhaustion tests at 110% of PPO. Participants rinsed their mouth with 25ml of 6.4% of CHO or placebo (PLA) solution immediately before the time-to-exhaustion test, using a crossover design. The contribution of the energy systems was calculated using the free software GEDAE-LaB®. Results: Time to exhaustion was similar between the conditions (CHO:174.3±42.8s; PLA:166.7±26.3s; p=0.33). In addition, there was no difference between the CHO and PLA condition for aerobic (CHO:135.1±41.2kJ and PLA:129.8±35.3kJ, p=0.34), anaerobic lactic (CHO:57.6±17.1kJ and PLA:53.4±15.1kJ, p=0.10), and anaerobic alactic (CHO:10.4±8.4kJ and PLA:13.2±9.2kJ, p=0.37) contribution. Consequently, total energy expenditure was similar between conditions (CHO:203.2±46.4kJ and PLA:196.5±45.2kJ, p=0.15). However, CHO mouth rinse reduced the RPE at the moment of exhaustion (CHO:18.2±1.0units and PLA:19.1±1.1units; p=0.02). Conclusion: CHO mouth rinse neither increased time to exhaustion nor altered energy systems contribution during a high-intensity exercise, but reduced the perceived effort at the exhaustion.(AU)

Effects of carbohydrate intake on time to exhaustion and anaerobic contribution during supramaximal exercise / Efeito da ingestão de carboidrato sobre o tempo de exaustão e contribuição anaeróbia durante exercício supramáximo

ABSTRACT Objective: This study evaluated the effect of carbohydrate intake on time to exhaustion and anaerobic contribution during supramaximal exercise on a cycle ergometer. Methods: The sample comprised ten participants with a mean age of 23.9±2.5 years, mean body mass of 75.1±12.3 kg, mean height of 170.0±1.0 cm, and mean body fat of 11.3±5.2%. The participants underwent an incremental test to determine maximal oxygen uptake and maximum power output, and two supramaximal tests with a constant load of 110% of the maximum power output to exhaustion. Thirty minutes before the supramaximal tests the participants consumed carbohydrates (2 g.kg-1) or placebo. Results: The times to exhaustion of carbohydrate and placebo did not differ (carbohydrate: 170.7±44.6s; placebo: 156.1±26.7s, p=0.17; effect size=0.39). Similarly, the anaerobic contributions of the two treatments did not differ (carbohydrate: 3.0±0.9 L; placebo: 2.7±1.1 L, p=0.23; effect size=0.29). Conclusion: Carbohydrate intake was not capable of increasing time to exhaustion and anaerobic contribution in physically active men cycling at 110% of maximum power output.

RESUMO Objetivo: Este estudo foi conduzido com o intuito de verificar o efeito da ingestão de carboidrato sobre o tempo de exaustão e a contribuição anaeróbia durante o exercício supramáximo em uma bicicleta ergométrica. Métodos: Dez participantes fizeram parte da amostra (idade: 23,9±2,5 anos; massa corporal: 75,1±12,3 kg; estatura: 170,0±1,0 cm; gordura corporal: 11,3±5,2%). Todos realizaram um teste incremental para determinar o consumo máximo de oxigênio e a potência máxima e dois testes supramáximos com carga constante de 110% da potência máxima até a exaustão. Os participantes ingeriram carboidrato (2 g.kg-1) ou placebo 30 minutos antes dos testes supramáximos. Resultados: Não houve diferença significativa no tempo de exaustão entre carboidrato e placebo (carboidrato: 170,7±44,6s; placebo: 156,1±26,7s, p=0,17; effect size=0,39). De forma similar, não houve diferença significativa na contribuição anaeróbia entre as condições (carboidrato: 3,0±0,9 L; placebo: 2,7±1,1 L, p=0,23; effect size=0,29). Conclusão: A ingestão de carboidrato não foi capaz de aumentar o tempo até a exaustão e a contribuição anaeróbia em exercícios à 110% da potência máxima em homens fisicamente ativos.

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

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.