Carbohydrate Mouth Rinsing: Improved Neuromuscular Performance During Isokinetic Fatiguing Exercise

PURPOSE: To determine whether repeated CHO mouth rinsing would improve neuromuscular performance during high intensity fatiguing contractions. METHODS: 18 young men (26.1±5.0 yr; 22.9±1,9 BMI) performed 3 maximal voluntary isometric contractions (MVICPRE). Immediately after, they completed 10 s mouth rinse with either 6.4% maltodextrine solution [MAL] or 7.1% glucose solution [GLU] or water [W] or artificially sweetened solution [PLA] or a control trial with no rinse [CON] in a cross over protocol. 5 sets of 30 isokinetic fatiguing contractions at 180°s-1 and a MVICPOST with their elbow flexors were performed after each mouth rinse. Mechanical and electromyographic signals (EMG) were recorded from the biceps brachii muscle and parameters of interest analyzed. RESULTS: 1) When rinsing the mouth with a solution containing CHO, independently of the sweetness, isokinetic performance was enhanced as shown by the greater total work achieved in comparison with CON; 2) the decay of torque and mean fiber conduction velocity (MFCV) recorded at the end of the fatiguing task was lower when rinsing the mouth with GLU compared to CON; 3) the torque recorded during the MVICPOST was greater with CHO with respect to CON and this was associated to a lower decay of MFCV. CONCLUSIONS: CHO mouth rinse counteracts the fatigue-induced decline in neuromuscular performance, supporting the notion that CHO rinse may activate positive afferent signals able to modify the motor output. Repeated mouth rinsing with sweet and non-sweet CHO-containing solutions can improve neuromuscular performance during an isokinetic intermittent fatiguing task.