The effect of carbohydrate mouth-rinsing on time trial performance

Muscle and liver glycogens stores can provide sufficient energy for high
intensity exercise of approximately 45-60 minutes. Therefore it shouldn't be
necessary to ingest extra carbohydrates during exercise.
However, some studies do show an increase in performance when carbohydrates are
taken orally during this kind of exercise. But when carbohydrates were provided
via intravenous infusion, this effect disappeared. Therefore, the question rose
if this performance benefit has a metabolic cause or that a central mechanism
via oral receptors plays a role. The latter could lead to an improved central
drive or motivation.
One way to investigate the effect of carbohydrates in the mouth on performance
is by use of mouth-rinsing.

The effect of carbohydrate mouth-rinsing on time trial performance and rates of
perceived exertion, compared to a placebo.

This is a randomized controlled trial with a cross-over design.
Drinks are provided in a double blind order.
Subjects have to visit the university at four occasions, separated by one week.
1. To measure subjects' Wmax and VO2max, a incremental exhaustive exercise test
on a bicycle ergometer is performed.
2. Familiarization of the time-trial.
3. First time trial, in which either the intervention solution or the placebo
is used for mouth rinsing.
4. Second time trial, in which the second solution is given.

Subjects will perform three time-trials.
One to get familiar with the procedure and two for testing the difference
between mout-rinsing with a carbohydrate or a placebo solution during exercise.
Subjects will receive a standardized breakfast in the morning of the testday.
And after a resting period of 2 hours they will start the time-trial. The only
information that they receive during the test is the amount of workload that
they completed (on a scale from 0-100%). Every 12.5 % completed they will
receive 25 ml of the test solution to rinse their mouth for 5 seconds. And
every 25% completed they are asked for their rate of perceived exertion on a
6-20 point scale.
The time-trial will take approximately 1 hour to complete, and time differences
between trials are the primary outcome measure.

not applicable