Carbohydrate Mouth Rinsing: Improved Neuromuscular Performance During Isokinetic Fatiguing Exercise

Abstract

Purpose: To determine whether repeated carbohydrate (CHO) mouth rinsing would improve neuromuscular performance during high-intensity fatiguing contractions.

Methods: Eighteen young men (age 26.1 ± 5.0 y, BMI 22.9 ± 1.9) performed 3 maximal voluntary isometric contractions (MVIC_PRE). Immediately after, they completed 10-second mouth rinse with 6.4% maltodextrin solution (MAL), 7.1% glucose solution (GLU), water (W), artificially sweetened solution (PLA), or a control trial with no rinse (CON) in a crossover protocol. Subjects performed 5 sets of 30 isokinetic fatiguing contractions at 180°/s, and an MVIC_POST with their elbow flexors was performed after each mouth rinse. Mechanical and electromyographic (EMG) signals were recorded from the biceps brachii and parameters of interest analyzed.

Results: 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. 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 than with CON. The torque recorded during the MVIC_POST was greater with CHO with respect to CON, and this was associated to a lower decay of MFCV.

Conclusions: CHO mouth rinse counteracts fatigue-induced decline in neuromuscular performance, supporting the notion that CHO rinse may activate positive afferent signals able to modify motor output. Repeated mouth rinsing with sweet and nonsweet CHO-containing solutions can improve neuromuscular performance during an isokinetic intermittent fatiguing task.

Keywords: elbow flexors; electromyography; isokinetic dynamometry; strength.