Effect of Carbohydrate Mouth Rinse on Performance after Prolonged Submaximal Cycling

ABSTRACTPrevious studies have shown improved shorter-duration (~1 h) performance with carbohydrate (CHO) mouth-rinsing (WASH), especially in overnight fasted/non-fuelled subjects.Purposeto determine the effect of WASH on cycling time-trial (TT) performance and muscle activity (EMG) after 2 h of sub-maximal cycling while receiving CHO.MethodsIn a double-blind, placebo-controlled crossover design, 10 well-trained males cyclists (VO2max: 65 mL·kg-1·min-1) completed two experimental trials. Each trial consisted of a standardized pre-trial snack (2-h prior) followed by 120 min of steady-state (SS) cycling (~60% VO2max) followed by a ~30 min TT, randomized as follows: 1) FEDWASH: 30g CHO·h-1 during SS + WASH during TT (every 20% of TT); 2) FEDPLA: 30g CHO·h-1 during SS + placebo-wash during TT.ResultsWhile FEDWASH was not significantly different than FEDPLA (P = 0.51), there was a 1.7% (+6.4 to -3.2% 90% CI; ES = 0.21) decrease in TT time (35s) for FEDWASH compared to FEDPLA, with qualitative probabilities of a 60% positive and 23% trivial outcome. For EMG, Soleus showed significant increase while 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 vs. FEDWASH.ConclusionsContrary to previous studies, this investigation utilized conditions of high ecological validity including a pre-trial 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's compared to placebo. Although marginal gains were achieved with a CHO mouth rinse (35 s), small performance effects can have significant outcomes in real-world competitions. 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 sub-maximal cycling while receiving CHO. Methods In a double-blind, placebo-controlled crossover design, 10 well-trained males cyclists (VO2max: 65 mL·kg-1·min-1) completed two experimental trials. Each trial consisted of a standardized pre-trial snack (2-h prior) followed by 120 min of steady-state (SS) cycling (~60% VO2max) followed by a ~30 min TT, randomized as follows: 1) FEDWASH: 30g CHO·h-1 during SS + WASH during TT (every 20% of TT); 2) FEDPLA: 30g CHO·h-1 during SS + placebo-wash during TT. Results While FEDWASH was not significantly different than FEDPLA (P = 0.51), there was a 1.7% (+6.4 to -3.2% 90% CI; ES = 0.21) decrease in TT time (35s) for FEDWASH compared to FEDPLA, with qualitative probabilities of a 60% positive and 23% trivial outcome. For EMG, Soleus showed significant increase while 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 vs. FEDWASH. Conclusions Contrary to previous studies, this investigation utilized conditions of high ecological validity including a pre-trial 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's compared to placebo. Although marginal gains were achieved with a CHO mouth rinse (35 s), small performance effects can have significant outcomes in real-world competitions. Correspondence: Matt Jensen, University of Victoria, Room 120, McKinnon Building, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada, Email: mpjensen@uvic.ca All authors approved the final version of the paper. This study was financially supported by MITACS accelerate fellowship and the Canadian Sport Institute - Pacific. The authors wish to thank all the participants for volunteering for the study. The authors have no conflict of interest and made every attempt to present the results of the study clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The authors also acknowledge that results of the present study do not constitute endorsement by ACSM. Accepted for Publication: 15 December 2017 © 2017 American College of Sports Medicine

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