Runners get boost from soft drinks reports ECU study
(June 15, 2002)
Heavily advertised "sport drinks" that quench the thirst of athletes and splash the backs of winning coaches can also improve the performance of long distance runners, a study at East Carolina University has concluded.
Monitoring a group of beverage-gulping marathon runners on treadmills, the researchers found that the athletes ran faster when their drinks contained a 6 - 8 percent mix of carbohydrates (sugar or glucose).
The 6 - 8 percent mixture is the standard in most commercial products such as Gatorade and Powerade. In the study, the runners reached the finish mark about 45 seconds faster while drinking the 6 - 8 percent carbohydrate mixture than when sipping flavored water or a drink mixed with a higher level of sugar. Sport drinks also contain electrolytes but the amount of this substance was not varied in the ECU research.
Dr. Matt Hickey of the ECU Human Performance Laboratory said the study modeled itself around a marathon because of the upcoming Summer Olympic Games. A field of 13 runners hoofed along on treadmills in a special "climate chamber" that emulated the features of a late July and early August day in Atlanta, Ga., the 1996 Olympic site. Instead of the regular 26 mile marathon distance, the researchers set the course for 20 miles with the first 17 miles controlled by the researchers. In the final three miles the runners set their own speeds.
"We were looking for a clear indication that performance was enhanced," said Hickey who worked on the project with ECU professors Richard G. Israel and Joseph Houmard, and graduate student Tyson Mahar.
Hickey noted that previous studies timed runners over a 26-mile course and found no statistical significance between those on water and those on sport drinks. He said that a difference of one minute or less over 26 miles may not be statistically significant even though a marathon runner might consider it crucial to the outcome of the race.
The ECU research team looked at the final three miles and ignored the other 17 so that they could focus on performance benefits late in the run. The carbohydrate electrolyte drinks improved performance over the final three miles by about 15 seconds per mile.
"When you think about it, that is fairly substantial," Hickey said. Another twist in the study was the variation in the carbohydrate levels mixed into the drinks. The study used three mixtures of six, eight and 10 percent carbohydrate content beverages. Water was used as a placebo with non-sugar sweeteners and flavors to make it taste the same as the other drinks. Hickey said the beverage with the highest concentration of sugars may have been too concentrated. He said the liquid probably remained in the stomach too long before being absorbed, but he said the ECU study did not measure how fast the stomach cleared the liquids.
Sport drinks were developed to be absorbed quickly by the body and restore the electrolytes lost when the body sweats. The carbohydrate additives serve as a fuel and thereby provide energy. Should athletes make regular use of these beverages? Many of the mid-level athletes, according to Hickey, don't drink during a race and he believes this is a mistake. He said the elite athletes, especially the Olympic Marathon runners and cyclists, know that drinking replaces electrolytes and adds fuel to their bodies. "Just watch the marathon runners during the games," he said. "Virtually all of them will be drinking the liquids. Even so, the attrition rate, because of the heat, will be high."
He noted that the original starting time for the Marathon event was set for late afternoon to accommodate television, but the American College of Sports Medicine expressed concern that the heat and humidity would be excessive. The start time has been reset to morning. "I would recommend that pe