Effect of Carbohydrate Mouth Rinse on Performance after Prolonged Submaximal Cycling

Previous studies have shown improved shorter duration (∼1 h) performance with carbohydrate (CHO) mouth rinsing (WASH), especially in overnight fasted/non-fuelled subjects. Purpose To determine the effect of WASH on cycling time trial (TT) performance and muscle activity (EMG) after 2 h of submaximal cycling while receiving CHO (FED). Methods In a double-blind, placebo-controlled crossover design, 10 well-trained males cyclists (V˙O2max: 65 mL·kg−1·min−1) completed two experimental trials. Each trial consisted of a standardized pretrial snack (2 h prior) followed by 120 min of steady-state (SS) cycling (∼60% V˙O2max) followed by an approximately 30-min TT, randomized as follows: 1) 30 g CHO·h−1 during SS + WASH during TT (every 20% of TT) (FEDWASH); 2) 30 g CHO·h−1 during SS + placebo (PLA) wash during TT (FEDPLA). Results Although FEDWASH was not significantly different than FEDPLA (P = 0.51), there was a 1.7% (90% confidence interval, +6.4% to −3.2%; ES, 0.21) decrease in TT time (35 s) for FEDWASH compared with FEDPLA, with qualitative probabilities of a 60% positive and 23% trivial outcome. For EMG, soleus showed significant increase, whereas medial gastrocnemius showed significant decrease in muscle recruitment from the beginning 20% TT segment to the last 20% only in the FEDPLA condition, which coincided with a slower (P = 0.01) last 20% of the TT in FEDPLA versus FEDWASH. Conclusions Contrary to previous studies, this investigation utilized conditions of high ecological validity including a pretrial snack and CHO during SS. Significant changes in muscle recruitment and time over the last 20% of the TT, along with an average 1.7% improvement in TT time, suggest CHO mouth rinse helps maintain power output late in TT compared with placebo. Although marginal gains were achieved with a CHO mouth rinse (35 s), small performance effects can have significant outcomes in real-world competitions.

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