Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
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©Journal of Sports Science and Medicine (2018) 17, 145 - 152

Research article
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, 
Author Information
1 Department of Kinesiology,
2 Applied 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
Publish Date
Received: 24-10-2017
Accepted: 19-01-2018
Published (online): 01-03-2018
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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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