Caffeine is the most commonly consumed drug in the world, and athletes frequently use it as an ergogenic aid. It improves performance and endurance during prolonged, exhaustive exercise. To a lesser degree it also enhances short-term, high-intensity athletic performance. Caffeine improves concentration, reduces fatigue, and enhances alertness. Habitual intake does not diminish caffeine's ergogenic properties. Several mechanisms have been proposed to explain the physiologic effects of caffeine, but adenosine receptor antagonism most likely accounts for the primary mode of action. It is relatively safe and has no known negative performance effects, nor does it cause significant dehydration or electrolyte imbalance during exercise. Routine caffeine consumption may cause tolerance or dependence, and abrupt discontinuation produces irritability, mood shifts, headache, drowsiness, or fatigue.
University of Washington, Department of Family Medicine, Roosevelt Medical Center, 4245 Roosevelt Way NE, Box 354775, Seattle, WA 98105, USA. spaluska@u.washington.edu
APPENDIX: Caffeine as an 'ergogenic aid' to athletic performance
An ergogenic aid is a substance or technique that improves physical performance. Caffeine is an effective ergogenic aid, particularly for athletic events that involve endurance (e.g. marathon running, triathlon, long distance swimming). Caffeine has been shown to increase the use of fat as an energy substrate, thereby sparing glucose. For athletes who do choose to consume caffeine as an ergogenic aid, it is important to remember that there is a limit to the amount an athlete may consume before breaching the rules of the International Olympic Committee (IOC). Also, as noted in the main body of
this FAQ, excess caffeine intake can lead to impaired performance.
The amount of caffeine an athlete can consume safely, and that may induce a performance enhancement, will vary according to previous history of caffeine intake, body size, concurrent intake of other caffeine-containing products, and the timing of consumption in relation to the athletic activity. Many athletes who consume caffeine beverages are unaware of their individual acceptable level of intake. An ergogenic benefit for endurance performance
can be expected at a moderate intake (3-5 mg caffeine/kg body weight) with a very low risk of being tested above the acceptable IOC level for urinary caffeine concentration (which must not exceed 12µg/mL). For a 60-70 kg athlete, 3-5 mg caffeine/kg body weight corresponds to about three cups of coffee or three cans of caffeinated energy drink (assuming 80 mg of caffeine per can). Caffeine concentration in the blood peaks about 2-4 hours after
caffeine consumption, so the caffeine boost is likely to be maximal when needed if the caffeine beverage is taken shortly before the endurance athletic event (e.g. 1-2 hours prior to the start).
A higher caffeine intake will not cause any greater performance benefit. In fact it may produce an illegal urinary level of caffeine and/or negative side effects. With many energy drinks having a high caffeine content, and often not being clearly labelled, the risk for excess intake of caffeine is likely to be high particularly for small or younger athletes.
The advice in this Appendix should not be construed as a recommendation to an endurance athlete to take caffeine to improve performance. Rather, if you do take caffeine, the advice is intended to minimise the risk of taking excessive quantities. |
Caffeine is one of the most comprehensively studied ingredients in the food supply, with centuries of safe consumption in foods and beverages. In 1959, the U.S. Food and Drug Administration (FDA) designated caffeine in cola drinks as "Generally Recognized as Safe" (GRAS). The FDA considers caffeine safe for all consumers, including children. In 1997, following extensive review, the FDA "found no evidence to show that the use of caffeine in carbonated beverages would render these products injurious to health." More than 140 countries have specifically considered the safety of caffeine and allow its use in beverages at various levels. |
Caffeine long term use: People who use large amounts of caffeine over long periods build up a tolerance to it. When that happens, they have to use more and more caffeine to get the same effects. Heavy caffeine use can also lead to dependence.
Caffeine & Sleep: If taken too close to bedtime, caffeine can interfere with sleep. Even if it does not prevent a person from falling asleep, it may disturb sleep during the night.
Caffeine & Alcohol: The notion that caffeine helps people sober up after drinking too much alcohol is a myth. In fact, using caffeine and alcohol together is not a good idea. The combination can lead to an upset stomach, nausea, and vomiting.
Caffeine Sensitivity: Older people may be more sensitive to caffeine and thus more likely to have certain side effects, such as irritability, nervousness, anxiety, and sleep problems.
Caffeine and Children: Children under the age of 12 should normally avoid caffeine.
Caffeine and Pregnancy: Pregnant and breastfeeding woman should avoid the use of caffeine.
Caffeine and Medicine: Consult your doctor for advice if you are taking any medicine.
Caffeine Warning: Do not use any product containing caffeine if you have known intolerance or sensitivity to caffeine.
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