Carbohydrate Mouth Rinse Counters Fatigue Related Strength Reduction

Abstract

The purpose was to determine the effect of carbohydrate (CHO) mouth rinse on maximal voluntary contraction (MVC) and neuromuscular output in a fatigued state. It was hypothesized that CHO mouth rinse would potentiate torque output in a fatigued state. In a double-blind, cross-over design, 12 competitive male athletes (9 rowers, 1 cyclist, 1 runner and 1 volleyball player) initially performed 3 × 5 s MVC isometric knee extensions followed by a 50% MVC contraction until volitional exhaustion, with quadriceps muscle activity measured via electromyography (EMG). Immediately after, either an 8% CHO maltodextrin (WASH), or noncaloric artificial sweetener (PLA) was mouth rinsed for 10sec, before 3 × 5 s final MVCs. Fatigue caused a significant decline in post fatigue MVC trial 1 for 3 s average torque (p = .03) and peak torque (p = .02) for PLA. This fatigue related decline in torque was not noticed for WASH, with a 2.5% and 3.5% less attenuation in peak and average torque, respectively in post fatigue MVC1 compared with PLA. The effect size for MVC trial 1 between WASH/PLA was seen to be small positive (ES = 0.22; 55% likelihood of positive). Overall for EMG RMS, there were no significant differences between PLA and WASH among all muscles. EMG median frequency showed comparable results between conditions with significant reductions due to fatigue. Taken together, this evidence suggests that the attenuation of torque post fatigue was less for CHO mouth rinse than a placebo. Even though the gains were marginal, these discoveries may play an important role in sport performance, as small performance effects can have significant outcomes in real-world competitions.

Carbohydrate Mouth Rinsing Enhances High Intensity Time Trial Performance Following Prolonged Cycling

“…As mentioned earlier, CHO MR is believed to enhance physical performance by activating areas of the brain associated with reward/pleasure, thereby increasing excitatory/motor output and muscular performance. One criterion measure of this response is peak muscle strength, and though not unanimous [ 39 ], mouth rinsing with CHO can partially restore peak strength following fatiguing contractions [ 40 ], following 60 min of cycling [ 41 ], as well as attenuate force diminution during sustained muscle contractions [ 42 ]. We evaluated peak torque during a maximum voluntary contraction before and after the MR treatment, following the prolonged cycling stimulus.…”

“…The discrepancy between this and previous reports may be due to treatment dosing, specifically that the mouth rinse dose that separated pre- and post-strength measurements here may not have been enough to elicit a treatment effect. Strength measurements obtained in the current project were assessed before and after a single dose swirled in the mouth for 5 s, which is much shorter than the 10 s [ 40 ] and 60 s [ 42 ] rinses provided in the studies documenting strength improvements. This explanation is strengthened by a previous report that endurance performance is enhanced to a greater extent following 10 s compared to 5 s rinses [ 43 ].…”

Fueling for the Field: Nutrition for Jumps, Throws, and Combined Events

“…An additional, and potentially alternative intervention to AWL that could be implemented by field event athletes in competition is CHO mouth rinsing, which has been shown to have a nearly instantaneous impact on NM performance outcomes (Gant et al, 2010;Jensen et al, 2015). This intervention avoids body weight gain from drinking fluids, does not cause adverse gastrointestinal effects (e.g., "sloshy gut"), and is very easy to implement throughout competition.…”

Carbohydrate Mouth Rinse Improves Mean Power During Multiple Sprint Performance

“…The mechanism responsible for these performance improvements has been attributed to the presence of carbohydrate in the oral cavity activating the insular cortex or the reward center of the brain ( 7 , 15 , 27 ). Increasing evidence supporting performance benefits with the use of a CMR ( 6 , 7 , 9 , 16 , 18 , 23 ) has led to current ACSM guidelines recommending that CMR for sustained high intensity exercise lasting 45–75 min ( 1 ). The influence of CMR on shorter, maximal intensity activities is less understood.…”