Skip to Content

Sports Science

Find a Doctor


To search Houston doctors, please select a specialty & submit your Zip Code below.

Advanced Search
Search by Doctor's Name

Schedule Now

Caffeine and Athletic Performance

caffeine for athletesCaffeine is perhaps the most readily available stimulant in the world, yet the NCAA and the International Olympic Committee (IOC) consider it a “controlled or restricted substance.” While optimum dosages can enhance sports performance, overuse can have harmful side effects.

Athletes must know how much caffeine is safe, when to use it, and be careful not to consume too much of it. The specialists at IRONMAN Sports Medicine Institute say that sometimes patients complain about fatigue and say that caffeine is not giving them energy.

Because caffeine is a diuretic, excessive amounts can cause excessive urination that leads to dehydration. Other detrimental side effects caused by overuse include anxiety, jitters, insomnia, irritability, gastrointestinal problems and increased heart rate, including arrhythmias or irregular heartbeats.

Calculating Caffeine Amounts

Caffeine is a naturally occurring substance found in the leaves, stems, seeds and roots of many plants. While most people know it is in coffee, soft drinks and tea, a smaller percentage of the population knows that caffeine is in chocolate, diuretics, some over-the-counter and prescription medications, herbal stimulants and even chewing gum.

The acceptable caffeine limit for NCAA athletes is 15 micrograms per milliliter of urine. The IOC allows its athletes up to 12 micrograms per milliliter of urine before the substance is considered illegal.

The American College of Sports Medicine estimates that a person weighing 154 pounds who consumes 5 to 6 regular size cups of coffee, approximately one hour before a workout of 1 to 1.5 hours, would have a urinary caffeine level approaching the IOC limit.

Of course, trying to determine how much caffeine is in any given beverage can be confusing. A 2010 report by the Journal of Food Science indicates that plain brewed coffee averages 133 milligrams of caffeine per 8 ounces; an equivalent size espresso contains 320 milligrams of caffeine. Compare that with findings published in a 2012 newsletter of the Center for Science in the Public Interest. It shows an 8-ounce cup of joe from a well-known fast food restaurant has only 67 milligrams of caffeine. The same newsletter shows an equivalent size espresso from a popular American-based coffeehouse contains 600 milligrams of caffeine.

Given such a wide variance in caffeine content, it’s probably wise to read labels and research how much caffeine is in your favorite beverages. Coffee generally has more caffeine than tea or soft drinks. Most colas contain 30 to 50 milligrams of caffeine per 12-ounce serving.

When to Consume Caffeine

The specialists at IRONMAN Sports Medicine Institute believes the optimum time to consume caffeine is 30 to 60 minutes prior to a sports activity and the optimum amount before endurance events is two to three cups of regular coffee. Caffeine can increase performance in endurance sports, but just like overtraining for a sport, too much of a good thing can actually hurt their performance.

Schedule an appointment with an IRONMAN Sports Medicine Institute affiliated physician »