Ask the RD

Answer: Athletes have been using caffeine as a way to boost performance as far back as the early 1900s, and many still use it today to gain an edge. There was a time, however, when caffeine was banned by the World Anti-Doping Agency (WADA). In 2004 the ban was lifted, but the substance is currently part of a monitoring program that assesses patterns of misuse.

While caffeine is considered a safe and effective supplement for enhancing exercise performance, some specifics should be sifted out before you go on a preworkout coffee binge.

Does caffeine benefit all types of exercise?

Studies have determined that caffeine is most effective for prolonged endurance events lasting more than 30 minutes but can also be beneficial for shorter, high-intensity events lasting 30 seconds to 3 minutes. Caffeine has not proved effective for improving anaerobic exercise (e.g., weightlifting) performance.

How much caffeine will provide a performance boost?

Consuming 2–6 milligrams of caffeine per kilogram of body weight 1 hour prior to exercise or during the athletic event has been found to improve athletic performance. Recommended doses for recreational or amateur athletes are on the lower end of the scale. As an example, a 130-pound woman may see benefits from 118 mg of caffeine, which is the equivalent to a cup of coffee.

Is coffee the best source?
Despite coffee being the most common source of caffeine intake, little evidence supports its use for improving athletic performance. A study published in the Journal of Applied Physiology examined the effects of different caffeine sources and determined that, despite having the same caffeine content as other tested beverages, coffee did not improve performance. The authors proposed there may be compounds in coffee that interrupt caffeine’s ergogenic effect (Graham, Hibbert & Sathasivam 1998).

Bottom Line
Caffeine may help boost your athletic performance, with non- coffee-based beverages providing the best sources. However, since caffeine intake may have adverse effects—such as gastrointestinal distress, an increased need to urinate, and nausea—you should experiment with intake during training and not competition.