As the 2008 summer Olympics approach, athletes are acutely aware they may be randomly tested for performance enhancing drugs---and will be tested should they be fortunate enough to medal. Limited levels of caffeine have always been allowed in the games. But too much could cause disqualification and that risk led many to abstain even though urinary concentrations had to exceed 12 mcg/ml for a positive test. Furthermore, many athletes had the mistaken impression that the amount needed to improve performance made failure of a drug test a distinct possibility. Generally speaking, 500mg in some individuals and at least 800mg in most individuals could trigger a positive test if ingested at over a short period of time.

Caffeine is now completely legal for Olympic competition. We will review a variety of recent studies which show caffeine can enhance performance at doses far lower than what causes side-effects such as irritability, anxiety, palpitations, insomnia, arrhythmias, headaches and gastrointestinal distress in all but those who have intolerance or hypersensitivity.

McNaughton and Minikin¹ state research on caffeine as an ergogenic aid began to appear in the 1930s and 1940s. In general, the doses used were very high-- 10 milligrams per kilogram of body weight (10 mg/kg/bw) or more². Research tended to yield mixed results. (Subjects were either helped or harmed) Positive studies with lower doses (250 mg) demonstrated that there was a wide range of individual response.³ We now know that with caffeine, more is not necessarily better and too much is worse than not enough.

Since I first wrote about caffeine⁴ opinions (including my own) have changed. Th At that time, I did not recommend caffeine as an ergogenic aid due to its side-effect profile which was often seen in early studies. In researching this article, I discovered that the American College of Sports Medicine was also opposed to the use of caffeine as a performance enhancer.⁵

Contemporary studies on caffeine have shown it can help athletic performance with a variety of doses under a number of experimental protocols. Here are some examples:

• A morning dose of caffeine at 5 mg/kg/bw improved the time to exhaustion in a cycling time trial five hours after ingestion.⁶
• It increased both speed in repeated sprinting and passing accuracy in conditions that simulated a rugby match using 6 mg/kg/bw.⁷
• Caffeine given to subjects in a simulated team sporting event consisting of four 22-minute quarters of drills (sprints, jumps, skills, and mental function) revealed that at just 2 mg/kg/bw, cognitive tasks were improved.⁸
• In a study that simulated a tennis match over a 90-minute period, 3 mg/kg/bw did not improve play versus placebo when measured at the 30 and 60-minute marks. But at 90 minutes, when subjects were fatigued, the caffeine was clearly beneficial.⁹
• Volunteers were given approximately 2.5 mg/kg/bw over the course of a two-hour vigorous bicycle race which was then followed by a 15-minute time trial. Caffeine did not affect the first two hours but, when the athletes were tired those on caffeine generated greater speed and force in the 15 minute sprint.¹⁰
• At 2 mg/kg/bw, caffeine increased the number of bench press repetitions from 32 to 34 over three sets with a one-minute rest period.¹¹

Next month, we will address the biggest misconception about caffeine and sports. (Hint, it is not a diuretic).

References

1. McNaughton, L., Minikin, B. et al. Ergogenic Effects of Caffeine: A Concise Review International Clinical Nutrition Review 1990;10(1):260-264.
2. Foltz, E., Idy, A., Barborka, C. et al. The Influence of Amphetamine Sulfate B-Desoryephedrine Hypochloride and Caffeine Upon Work Output and Recovery When Rapidly Exhausting Work is Done by Trained Subjects. Journal of Laboratory and Clinical Medicine 1943; 28:603-606.
3. Iv, J.L., Costill, D.L., et al. Influence of Caffeine and Carbohydrate Feedings on Endurance Performance Medicine and Science in Sports and Exercise Med Sci Exerc 1979:6-11.
4. Andersen, G.D. Caffeine and Sports Dynamic Chiropractic 1991;9(5),10.
5. Davis, T.N. Various Effects of Caffeine Upon the body. International Clinical Nutrition Review 1990;10(2):333-335
   
6. Bell, D.G, McLellan, T.M., et al. Repeated Exercise Performance and Caffeine Ingestion Medicine and Science in Sports and Exercise Med Sci Exerc 2003;35(5):S267
7. Stewart, G.R., Hopkins, W.G., Cook, C., Caims, S.T., et al. Multiple Effects of Caffeine on Simulated High-Intensity Team-Sports Performance Medicine and Science in Sports and Exercise Med Sci Exerc 2005;37:1998-2005.
8. Chen, S.C., Davis, J.M., Mattews, E., et al. Effects of Caffeinated Sports Drinks on Physical/Mental Function During Team Sports Exercise. Medicine and Science in Sports and Exercise Med Sci Exerc 2007;39(5):S43, A-700.
9. Strecker, E., Foster, E.B., Taylor, K., et al. The Effect of Caffeine Ingestion on Tennis Skill, Performance and Hydration Status. Medicine and Science in Sports and Exercise Med Sci Exerc 2007;39(5):S100, A- 953.
10. Trilik, J.L., Millard-Scafford, M.L., Cureton, K.J., et al. Hydration During Exercise in Warm Humid Conditions: Effect of a Caffeinated Sports Drink. Medicine and Science in Sports and Exercise Med Sci Exerc 2007;39(5):S100, A-954.

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