Sports Drinks Boost Performance When Spat Out
When Timothy Noakes first proposed that exercise fatigue is regulated by the brain in the early 1990s, most of his fellow exercise physiologists thought he was crazy. Since then, however, evidence in favor of Noakes's hypothesis has been piling up.
Some of the most interesting recent evidence comes from research on sports drinks showing that carbohydrate-containing fluids enhance exercise performance even when they are merely swished around in the mouth and then spat out--never swallowed. ScienceDaily has reported on one of these studies, which appears in the current edition of the Journal of Physiology. In this study, trained endurance athletes completed a stationary bike time trial on three occasions, rinsing their mouths out with a glucose drink, a maltodextrin drink, or water flavored with artificial sweetener. On average, the subjects complete the time trial 2 to 3 percent faster when rinsing their mouths with the glucose and maltodextrin drinks.
As a separate part of this study, the researchers used fMRI to look inside the subjects' brains after the consumed each of the three beverages. They found that the glucose and maltodextrin drinks activated a reward center of the brain while flavored water did not. Combined with the time trial results, this is evidence that the sports drinks enhance performance not only by supplying energy to the muscles but also by reducing the perceived effort associated with a given level of exercise output. In the ScienceDaily report, the study's lead author, Ed Chambers, says, "Much of the benefit from carbohydrate in sports drinks is provided by signalling directly from mouth to brain rather than providing energy for the working muscles." |
