Athletes still taking caffeine to boost performance

By Amy Norton

NEW YORK (Reuters Health) - Many competitive athletes believe that taking caffeine gives them an edge, despite doubts that it works -- and the "placebo effect" might help explain why, according to new research.

Four years ago, ahead of the Athens Olympics, the World Anti-Doping Agency (WADA) removed caffeine from its list of banned substances in sport. This was "presumably because WADA considered (caffeine's) performance-enhancing effects to be insignificant," notes Mark Stuart in a commentary published in the journal BMJ Clinical Evidence.

Stuart, a BMJ editor, has worked with doping control for past Olympic Games and helped train medical staff for the upcoming Beijing Olympics.

Despite questions about caffeine's effects on athletic prowess, Stuart points out, studies indicate that many athletes still use the stimulant. In a study published last month, for example, researchers found that of 193 UK track-and-field athletes they surveyed, one-third used caffeine to enhance performance -- as did 60 percent of 287 competitive cyclists.

So why do so many athletes continue to pop caffeine pills? It's possible that the placebo effect plays a role, Stuart told Reuters Health.

That is, athletes may perform slightly better after taking caffeine because they believe it works.

Stuart looked at two small studies that specifically addressed the placebo effect as it relates to caffeine and athletic performance.

In one, seven male cyclists were told that they would be given either caffeine or a placebo, but in fact none received caffeine. The researchers found that cyclists who believed they had taken the placebo showed a decline in their cycling performance compared with their baseline tests. In contrast, cyclists who believed they had been given caffeine improved their performance.

Similarly, a study of 14 male cyclists published this year showed what seemed to be a "nocebo" effect: athletes who knew they were being given a placebo instead of caffeine showed a decrease in their performance. In other words, their performance may have suffered because they knew they were not getting caffeine.

Both studies were very small, Stuart said, so the results "should be interpreted with extreme caution."

Still, he said, "the placebo effect does offer a possible explanation to ponder as to why some athletes continue to use (caffeine)."

"There is an obvious difference," Stuart writes in his editorial, "in the perception of caffeine as a performance-enhancing substance between WADA and the many elite athletes who continue to use it."

"Regardless of this difference," he adds, "and given the evidence-driven backing of WADA from the scientific community, the potential for widespread caffeine use at this month's Olympics will, hopefully, not threaten the integrity of fair play in sport."

SOURCE: BMJ Clinical Evidence 2008.