One taste, and full power ahead - researchers find instant carbo boost

The body can tell energy is on the way as soon as food enters the mouth - even before it is swallowed - University of Auckland researchers have found.

Scientists have shown for the first time that the mere presence of carbohydrate solution in the mouth immediately boosts muscle strength - suggesting a previously unknown neural pathway is activated when oral receptors detect carbohydrates.

"There appears to be a pathway in the brain that tells our muscles when energy is on the way," said lead researcher Nicholas Gant from the university's department of sport and exercise science.

"We have shown that carbohydrate in the mouth produces an immediate increase in neural drive to fresh and fatigued muscle and that the size of the effect is unrelated to the amount of glucose in the blood or the extent of fatigue."

The research has been published in the journal Brain Research.

Sixteen healthy young men, who had been doing biceps exercises for 11 minutes, were given a carbohydrate solution to drink or an energy-free placebo.

Within one second of swallowing the drink, their neural activity increased by 30 per cent and muscle strength 2 per cent, with the effect lasting for around three minutes.

"It might not sound like much, but a 2 per cent increase in muscle strength is enormous, especially at the elite level," said co-author Cathy Stinear.

" It's the difference between winning an Olympic medal or not."

A second boost in muscle strength was observed after 10 minutes when carbohydrate reached the bloodstream and muscles through digestion, but neural activity was not boosted.

The solutions were of identical flavour and sweetness, confirming that receptors in the mouth could process other sensory information aside from the basic taste qualities of food.

"The results suggest that detecting energy may be a sixth taste sense in humans," Dr Gant said.

In another experiment, 17 participants who had not been exercising and were not fatigued held one of the solutions in their mouths without swallowing.

Measurements of the muscle between the thumb and index finger showed a similar, though smaller effect as in the first experiment, indicating the response happened in large powerful muscles and in smaller muscles.

It showed that carbohydrate in the mouth activates the neural pathway whether or not muscles are fatigued.

- NZPA