Research article - (2018)17, 145 - 152
Carbohydrate Mouth Rinse Improves Cycling Time-Trial Performance without Altering Plasma Insulin Concentration
Kevin O. Murray1, Hunter L. Paris1, Alyce D. Fly2, Robert F. Chapman1, Timothy D. Mickleborough1,
1Department of Kinesiology,
2Applied Health Science, School of Public Health-Bloomington, Indiana University, Bloomington, Indiana, USA

Timothy D. Mickleborough
✉ FACSM Professor and Director of Graduate Studies, Department of Kinesiology, School of Public Health – Bloomington, 1025 E.7th St., HPER 112, Indiana University, Bloomington, Indiana, 47405 USA
Email: tmickleb@indiana.edu
Received: 24-10-2017 -- Accepted: 19-01-2018
Published (online): 01-03-2018
ABSTRACT

Rinsing the mouth with a carbohydrate solution has been shown to improve exercise performance in a manner similar to carbohydrate ingestion. However, the underlying mechanisms behind these ergogenic benefits remain unclear. This study evaluated whether rinsing the mouth with a carbohydrate solution alters plasma insulin and glucose concentration during the initial stages of a 40 km cycling time-trial. Eight trained, competitive cyclists [age (mean ± SEM) = 24 ± 2 y; V̇O2max = 64.5 ± 2.2 ml·kg-1·min-1] completed three simulated 40 km time-trials comprised of a familiarization trial, a carbohydrate condition (CHO) and a placebo mouth rinse condition (PLA). In the two mouth rinse conditions, rinsing was administered prior to onset of exercise and every 5 km throughout exercise. Plasma insulin was collected at 5 km intervals throughout the first 25 km, and glucose samples were collected at 5 km intervals throughout the exercise bout. No change in plasma insulin was detected between conditions (p = 0.638, ES < 0.03) for the first 25 km of the time-trial. Likewise, plasma glucose concentration did not differ between CHO and PLA (p = 0.801, ES < 0.01) and remained relatively stable throughout exercise. Time to complete the 40 km time-trial was significantly faster for CHO (67.1 ± 1.1 min) compared to PLA [67.9 ± 1.0 min; (P = 0.028, ES 0.27)]. Performance time was faster by an average of 1.1% (95% confidence interval range 0.2-2.0%) in the CHO condition. Exercise intensity (% V̇O2max) throughout the trial was similar between conditions (p = 0.846). Respiratory exchange ratio was not significantly different between conditions (0.88 ± 0.01 for PLA, and 0.91 ± 0.01 for GLC; p = 0.081). Performance gains elicited by a carbohydrate mouth rinse occurred independently of changes in plasma insulin concentration.
Key words: Sport nutrition, supplementation, exercise, ergogenic aid

Key Points
  • Carbohydrate mouth rinsing has been shown to improve endurance performance for exercise lasting approximately 1 h in duration. The mechanisms responsible for performance gains are yet to be fully understood.
  • Although 40 km cycling time-trial performance improved when rinsing the mouth with a carbohydrate solution compared to a placebo condition, rinsing the mouth with a carbohydrate solution prior to exercise and every 5 km throughout a 40 km cycling time-trial did not alter plasma insulin concentration.
  • Blood glucose concentration was not affected when rinsing the mouth with a carbohydrate solution every 5 km throughout a 40 km cycling time-trial.
  • Rates of macronutrient oxidation did not differ during exercise when rinsing the mouth with a carbohydrate solution compared to a placebo solution.








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Carbohydrate Mouth Rinse Improves Cycling Time-Trial Performance without Altering Plasma Insulin Concentration
Kevin O. Murray, Hunter L. Paris, Alyce D. Fly, Robert F. Chapman, Timothy D. Mickleborough
2018(17), 145 - 152.
DOI: https://doi.org/