April 21, 2009

Sport Drinks More Than Just Hype

According to a new research study, carbohydrate-loaded sports drinks really do enhance athletic performance "“ and moreover, they start working before you even swallow them.

Scientists testing the physical performance of athletes had them rinse their mouths with one of two high-carb sport drinks. Results showed an almost instantaneous improvement in the athletes' abilities.  When the same test was repeated with water flavored with sugar-free sweeteners, researchers did not observed the same effects.

Further examination using MRI scans of the brain showed that the simple act of swishing the carbohydrate-rich drink around in the mouth stimulated parts of the brain that are connected with pleasure and reward.  Again, when the test was repeated with artificially-sweetened water, the results were not the same.

The study, found in this month's edition of the Journal of Physiology, shows that these high-performance sports drinks may work by activating receptors in the mouth that connect directly to the reward center in the brain.

"Our study has shown that during intense exercise lasting around one hour, performance can be improved by simply rinsing a carbohydrate solution in the mouth," said chief researcher Dr. Ed S. Chambers of the University of Birmingham in England.

Chambers added, however, the results by no means mean that athletes should simply rinse and spit.  The body also needs the electrolytes and fluids provided by these drinks to replenish those lost during strenuous activity.

The study indicates, in effect, an additional benefit of sports drinks and not an alternative way of using them, he added.

The results used the findings of two separate studies, both involving eight trained cyclists.  Each of the participants engaged in rigorous exercise on a stationary bike and were tested at the beginning of the study and then again at later sessions. 

For the later tests, each athlete was given one of two sports drinks containing a mixture of either glucose and maltodextrin, or water sweetened with the artificial sweetener saccharine.

Researchers recorded a general improvement among all the athletes when they rinsed their mouth with the drinks containing real carbohydrates but not when they used the water-saccharine mixture.

An imaging technique known as fMRI showed that the high-carbohydrate drinks stimulated a region of the brain connected with both control of movement and pleasure.  Researchers hypothesize that this combined stimulus likely allowed the athletes to push themselves harder without feeling the immediate effects of increased physical stress.

When the body is engaged in prolonged exercise, explained Chambers, it begins to send "negative" signals to the brain "“ such as increased body temperature and joint or muscle pain "“ that tell essentially tell it to slow down.  The brain then responds by lowering the "central drive" to the muscles being used, thus reducing their relative power output.

"We propose that when an oral carbohydrate stimulus is present during exercise, this "Ëœpositive' signal to the brain maintains the central drive to the exercising muscle, thus improving performance," explained Chambers.

The results of the study seem to weaken the claims of critics that sport drinks are all hype and that pure water is the best fluid-replenisher. 

The market for sports drinks has exploded since Gatorade was first invented in 1965.  Beverage giants like Pepsi Cola Inc. and Coca-Cola have branched-out into this highly profitable market, earning millions annually with targeted drinks like Gatorade and Powerade.


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