Caffeine for Athletes
Caffeine is the most casually and widely used ergogenic aid in the world. Elite athletes and regular exercisers alike use it. Caffeine is found naturally in chocolate, coffee, tea and is added to foods such as soft drinks.
Claimed ergogenic properties
Lowers perception of effort, wards off drowsiness and increases alertness by stimulating the central nervous system.
Increases the amount of energy derived from fat, thus theoretically sparing glucose and glycogen stores and delaying the onset of fatigue in long distance runs (over 20 miles).
Scientific evidence for these ergogenic properties
Well-controlled laboratory studies involving running or cycling after taking placebo or 3-13 mg caffeine/kg body weight 1 hour before exercise have shown that caffeine improves endurance by prolonging time to exhaustion [1,2].
There is a distinct lack of evidence, however, that caffeine is effective in the field and as it is a diuretic [3], and thus promotes dehydration, it could impair performance, especially in hot conditions.
To date, research has been almost exclusively carried out on men so more research is needed to examine if the ergogenic properties of caffeine are as effective for women [4].
Even small doses (the equivalent of one small cup of coffee) can enhance performance [1,2].
Cautions
The International Olympic Committee (IOC) has banned caffeine above a urine level of 12 micrograms/ml. This would be the result of drinking 4 large cups of coffee.
Caffeine crosses the placenta and is transferred into breast milk so it is not recommended for pregnant or breast feeding women.
Some people become dependent on caffeine, experiencing withdrawal symptoms such as headaches, fatigue or drowsiness if they abstain.
As with all dietary supplements, make sure that you inform your physician of what you are taking.
Recommendations
To enhance performance, consume a cup of coffee or the equivalent amount of caffeine from a supplement or other food source (about 85 milligrams) an hour before endurance exercise. Larger amounts of caffeine are likely to be counterproductive.
Caffeine is available from food and beverage sources, but can also be found in pill form or even in a chewing gum in your local pharmacy. Check dosage information on the label to avoid taking too much.
References
1. Clarkson PM: Nutritional Ergogenic Aids: Caffeine. Int J of Sports Nutr. 3:103-111, 1993.
2. Graham TE, Spriet LL: Caffeine and Exercise Performance. Gatorade Sports Science Exchange 9(1), 1996.
3. Stookey JD: The diuretic effects of alcohol and caffeine and total water intake misclassification. European journal of epidemiology, 1999, Vol.15, No.2, pp.181-188.
4. Applegate E: Effective Nutritional Ergogenic Aids. Int J of Sports Nutr. 9:229-239, 1999.