Re: Receptors in the mouth in influencing exercise performance

[Guest guest]

It is also possible that with the assumption of new energy entering

the body, more energy reserves are made available. Energy that would

normally have been held back for emergency situations.

Anyway, I wonder if rinsing the mouth with CHO sollution or drinking

artificionally sweetened water was sometimes used as a placebo in

tests, and how that would have influenced the result.

Regards,

Johan Bastiaansen

Hasselt, Belgium.

>

> The effect of carbohydrate mouth rinse on 1-h cycle time trial

> performance.

>

> JM, Jeukendrup AE, DA.

>

> Med Sci Sports Exerc. 2004 Dec;36(12):2107-11. Links

>

> PURPOSE AND METHOD: To investigate the possible role of

carbohydrate

> (CHO) receptors in the mouth in influencing exercise performance,

> seven male and two female endurance cyclists (VO(2max) 63.2 +/- 2.7

> (mean +/- SE) mL.kg*(-1).min(-1)) completed two performance trials

in

> which they had to accomplish a set amount of work as quickly as

> possible (914 +/- 40 kJ). On one occasion a 6.4% maltodextrin

> solution (CHO) was rinsed around the mouth for every 12.5% of the

> trial completed. On the other occasion, water (PLA) was rinsed.

> Subjects were not allowed to swallow either the CHO solution or

> water, and each mouthful was spat out after a 5-s rinse.

>

> RESULTS: Performance time was significantly improved with CHO

> compared with PLA (59.57 +/- 1.50 min vs 61.37 +/- 1.56 min,

> respectively, P = 0.011). This improvement resulted in a

> significantly higher average power output during the CHO compared

> with the PLA trial (259 +/- 16 W and 252 +/- 16 W, respectively, P

=

> 0.003). There were no differences in heart rate or rating of

> perceived exertion (RPE) between the two trials (P > 0.05).

>

> CONCLUSION: The results demonstrate that carbohydrate mouth rinse

has

> a positive effect on 1-h time trial performance. The mechanism

> responsible for the improvement in high-intensity exercise

> performance with exogenous carbohydrate appears to involve an

> increase in central drive or motivation rather than having any

> metabolic cause. The nature and role of putative CHO receptors in

the

> mouth warrants further investigation.

>

> =========================

> Mouth rinse but not ingestion of a carbohydrate solution improves 1-

h

> cycle time trial performance.

> Scand J Med Sci Sports. 2008 Nov 3. [Epub ahead of print] Links

>

> Pottier A, Bouckaert J, Gilis W, Roels T, Derave W.

>

> The aim of the present study was to further explore the influence

of

> ingestion and mouth rinse with a carbohydrate-electrolyte solution

> (CES) on the performance during a approximately 1 h high-intensity

> time trial on trained subjects. Subjects rinsed around the mouth or

> ingested a 6% isotonic CES or placebo (14 mL/kg body weight) before

> and throughout a time trial in which they had to accomplish a set

> amount of work (975+/-85 kJ) as quickly as possible.

>

> In the mouth rinse conditions, time to complete the test was

shorter

> (P=0.02) with CES (61.7+/-5.1 min) than with placebo (64.1+/-6.5

> min), whereas in the ingestion conditions, there was no difference

> between placebo (62.5+/-6.9 min) and CES (63.2+/-6.9 min). Although

> power output and lactate concentration during exercise were

> significantly higher when subjects rinsed their mouth with CES

> compared with placebo, the rating of perceived exertion values did

> not differ. Blood glucose concentration increased after ingestion

of

> but not after mouth rinse with CES.

>

> The interesting finding of the present study is that rinsing the

> mouth with but not ingestion of CES resulted in improved

performance.

>

> =========================

> Ross Tucker and Dugas recently posted the below on their

> website:

>

> http://www.sportsscientists.com/search?updated-max=2008-11-27T11%

3A58%

> 3A00%2B02%3A00 & max-results=6

>

> Firstly, this study did NOT show that rinsing the mouth is better

> than swallowing the solution. It simply compared rinsing with CHO

to

> rinsing with H2O. It is not, therefore, an excuse not to drink

> glucose-containing drinks during exercise! (the second study

> discusses this a bit more).

>

> However, what it does do is help us understand how shorter exercise

> might be improved by carbohydrates. The authors of this study

> speculated that there are receptors in the mouth, which are

> stimulated by the CHO-drink (but not by water), and then trigger

> centres in the brain that then increase the central drive for

> exercise. Once again, this would suggest that the brain picks up

> the " reduction " in effort as a result of the glucose in the mouth,

> and the cyclist rides harder, with the result that the perception

> increases to the desired level at a higher overall performance

level.

> It supports the notion that the sensation and perception are the

> regulators of performance.

>

> ===================

> Carruthers

> Wakefield, UK

>