Sports Drinks may help boost performance via receptors in the mouth that send signals to the brain
February 24, 2016

High-carbohydrate sports drinks can boost athletic performance, and their effects may begin as soon as they hit the mouth. Dr. Ed S. Chambers, of the University of Birmingham in the UK asked endurance athletes to rinse their mouths with either of two carbohydrate containing drinks, the athletes' exercise performance improved. The same was not true when the athletes were given water flavored with an artificial sweetener. Brain scans showed that simply swishing the carbohydrate drinks around the mouth activated particular areas of the brain associated with pleasure and reward. The artificially sweetened water did not have the same effects. During intense exercise lasting around one hour, performance can be improved by simply rinsing a carbohydrate solution in the mouth. Sports drinks also help keep the body hydrated and supply electrolytes and other nutrients. The results are based on two studies, each involving eight trained cyclists. All of the athletes underwent exercise testing on a stationary bike, once at the start of the study and again on separate visits to the exercise lab.

During those later tests, the study participants were given one of the two carbohydrate drinks -- containing glucose, maltodextrin or water sweetened with saccharin.

The athletes improved upon their initial performance when they rinsed their mouths with either one of the carbohydrate drinks, but not when they used water.

Using a brain imaging technique called fMRI, Dr. Ed S. Chambers found that the carb drinks sparked activity in brain areas related to both movement control and pleasure.

The brain activation may help the athletes to work harder without feeling like they were.

During a long exercise bout, Chambers explained, the brain receives "negative" messages from the body, like elevated temperature and joint pain. The brain reacts by reducing the "central drive" to working muscles, curbing their power output.

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

Journal of Physiology, April 15, 2009.

Weight gain concern
Prev Chronic Dis. 2015. Association Between Student Body Mass Index and Access to Sports Drinks in Minnesota Secondary Schools, 2012-2013. This ecologic study evaluated the association between school policy allowing students to purchase sports drinks from school vending machines and school stores and student body mass index (BMI). Data were from surveillance surveys of Minnesota secondary schools (n = 238) and students (n = 59,617), administered in 2012 and 2013, respectively. We used generalized linear models to assess the association between policies and mean age- and sex-adjusted BMI percentile. In adjusted multivariate analysis, school policy was positively associated with BMI percentile. School policy restricting student access to sports drinks at school may contribute to decreasing consumption of sport drinks among school-aged youth and improving student weight outcomes in this population.

Content of milk protein
Br J Nutr. October 2013. Effect of varying the concentrations of carbohydrate and milk protein in rehydration solutions ingested after exercise in the heat. The present study further demonstrates that after exercise-induced dehydration, a carbohydrate--milk protein solution is better retained than a carbohydrate solution. The results also suggest that high concentrations of milk protein are not more beneficial in terms of fluid retention than low concentrations of milk protein following exercise-induced dehydration.