Date Posted: Dec 20, 2010
December 8, 2010, 12:01 am
Phys Ed: Do Energy Drinks Improve Athletic Performance?
By GRETCHEN REYNOLDS
Tony Cenicola/The New York Times.
By Monday, Four Loko, the alcohol-and-caffeine-laced energy drink, is scheduled to be removed from store shelves nationwide, following a ruling last month by the Food and Drug Administration that the safety of such beverages is unproven and that they should no longer be manufactured or sold. During the resulting media coverage, surprisingly little attention was focused on a corollary topic. What about nonalcoholic energy drinks, which will remain on sale? Are they safe? Effective? Who should be drinking them? Who shouldn’t?
With excellent timing, a number of new scientific studies and reviews have just been published that address those and related questions about energy drinks, particularly for athletes. Their findings and conclusions are thought-provoking.
Energy drinks, for those who would guess that a Red Bull is related to Paul Bunyan’s animal sidekick, are beverages that contain whopping doses of sugar (up to a quarter cup per can), caffeine and other ingredients, like the stimulatory herb guarana and the amino acid taurine. Although often marketed to (and by) athletes, they are not sports drinks. "Sports drinks," like Gatorade, "contain far less" sugar or other sweeteners than energy drinks and rarely if ever contain caffeine, said Dr. John P. Higgins, the director of exercise physiology at Memorial Hermann Sports Medicine Institute in Houston. Dr. Higgins, a cardiologist, is the lead author
of a new review about the ingredients and efficacy of energy drinks, published last month in Mayo Clinic Proceedings. "In many stores, you’ll see the energy drinks displayed right next to the sports drinks in store aisles, as if they were interchangeable," Dr. Higgins said. "They’re not."
That fact has not slowed the growing popularity of energy drinks among athletes, particularly those in college and younger. In a recent survey of American high-school athletes, 32 percent reported drinking energy beverages. In another survey, 27 percent of a group of 16,000 adolescent athletes, some as young as 11, said that they used caffeine, usually in the form of energy drinks, to improve their sports performance; 13 percent said they did so at the urging of their coaches.
But the evidence that energy drinks can make you a better athlete is sketchy at best. "There’s good evidence that caffeine is ergogenic," said Dr. Erin Duchan, a pediatrician and co-author of a review of the current science about energy drinks for athletes, published recently in The Physician and Sports Medicine. "It can, in the right circumstances, improve athletic performance," she added.
But the amounts of caffeine required to improve performance vary wildly from person to person, and the effects typically are lessened once an athlete is used to caffeine. A study of collegiate runners found that a sugar-free version of Red Bull, while loaded with caffeine, did not improve the athletes’ run-to-exhaustion times, possibly because the athletes were so habituated to the stuff.Meanwhile, because it is a diuretic, caffeine "can contribute to dehydration," Dr. Higgins said. And the large amounts of sugar in energy drinks have been known to cause diarrhea and other gastrointestinal upset, he said, "which is certainly not going to improve anyone’s performance."
The effects of energy drinks on young athletes are particularly mysterious. To date, very little research has been conducted involving children and young adults, although two studies released last week in Experimental and Clinical Psychopharmacology are telling. In one, collegians were given energy drinks that contained different levels of caffeine (including none) and asked to complete a test, during which they pressed a key when a green target flashed rapidly on screen and did nothing when a blue target appeared. The students who drank the caffeinated energy drinks had quicker reaction times than those who didn’t, but the better times and more accurate reactions were in the group that had the least caffeine.
The second study, while not looking directly at either energy drinks or young athletes, has implications concerning both. In it, healthy boys and girls between the ages of 12 and 17 drank sweet, flat soft drinks spiked with varying amounts of caffeine. The beverages were similar in taste to Red Bull. Then the children were set loose in the lab, which had been stocked with a variety of snack foods. The kids who had downed the most caffeine steered unerringly for the snacks containing the most sugar. That result indicates, the researchers wrote, that there may be an as-yet-unidentified link between "caffeine use and intake of higher energy-density foods" in children. The most highly caffeinated boys also showed a distinct increase in blood pressure, although this effect was not seen in the girls.
What all of this new research cumulatively means remains, at the moment, uncertain. "There is still far too little science about the effects of energy drinks in anyone, at any age," Dr. Higgins
said. "We don’t, for instance, have any research that I’m aware of about the long-term effects" of frequently drinking energy beverages, he said, and he said he knows of none being planned. The Food and Drug Administration does not regulate nonalcoholic energy drinks or the levels of the ingredients in them, and manufacturers are not required to prove their safety or efficacy.
So should you or your teenage soccer player be drinking energy drinks? Not if your aim is to improve sports performance, Dr. Higgins said. "I wouldn’t recommend energy drinks to athletes," he said. "Look at the name. These are not sports drinks."