Caffeine and Athletic Performance

As the 2008 Summer Olympics approach, athletes are acutely aware they might be randomly tested for performance-enhancing drugs and also will be tested should they be fortunate enough to medal. Limited levels of caffeine always have been allowed in the games, but too much could cause disqualification. That risk led many to abstain from caffeine, 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, 500 mg in some individuals and at least 800 mg in most could trigger a positive test if ingested in a short period of time.

Caffeine is now completely legal for Olympic competition. This article reviews various recent studies that 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 Minikin describe caffeine as an ergogenic aid that appeared in the 1930s and 1940s.¹ In general, the doses used were very high: 10 mg per kilogram of body weight (10 mg/kg/bw) or more.² Research tended to yield mixed results. (Subjects were either helped or harmed.) Positive studies with lower doses (250 mg) demonstrated there was a wide range of individual response.³ With caffeine, more is not necessarily better and too much is worse than not enough.

Since I first wrote about caffeine, opinions (including my own) have changed.⁴ At the time of my first article, I did not recommend caffeine as an ergogenic aid due to its side-effect profile, which was often seen in early studies. However, in researching this article, I discovered the American College of Sports Medicine also was 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 five hours after ingestion in a cycling time-trial.⁶
• At a dose of 6 mg/kg/bw, it increased both repeated sprinting speed and passing accuracy in conditions that simulated a rugby match.⁷
• Caffeine given to subjects in a simulated team 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 for a 90-minute period, 3 mg/kg/bw did not improve play versus placebo when measured at the 30- and 60-minute marks. 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, I 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):260-4.
2. Foltz E, Idy A, 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;28:603-6.
3. Iv JL, Costill DL, et al. Influence of caffeine and carbohydrate feedings on endurance performance. Medicine and Science in Sports and Exercise, 1979:6-11.
4. Andersen GD. "Caffeine and Sports." Dynamic Chiropractic, 1991;9(5):10.
5. Davis TN. Various effects of caffeine upon the body. International Clinical Nutrition Review, 1990;10(2):333-5.
6. Bell DG, McLellan TM, et al. Repeated exercise performance and caffeine ingestion. Medicine and Science in Sports and Exercise, 2003;35(5):S267.
7. Stewart GR, Hopkins WG, et al. Multiple effects of caffeine on simulated high-intensity team-sports performance. Medicine and Science in Sports and Exercise, 2005;37:1998-2005.
8. Chen SC, Davis JM, et al. Effects of caffeinated sports drinks on physical/mental function during team sports exercise. Medicine and Science in Sports and Exercise, 2007;39(5):S43.
9. Strecker E, Foster EB, et al. The effect of caffeine ingestion on tennis skill, performance and hydration status. Medicine and Science in Sports and Exercise, 2007;39(5):S100.
10. Trilik JL, Millard-Scafford ML, et al. Hydration during exercise in warm humid conditions: effect of a caffeinated sports drink. Medicine and Science in Sports and Exercise, 2007;39(5):S100.
11. Candow DG, Forbes SC, et al. The effect of caffeinated energy drinks on muscle endurance and Wingate and Wingate cycle performance in young adults. Medicine and Science in Sports and Exercise, 2007;39(5):S43
12. Armstrong LE, Pumerantz AC, et al. Fluids, electrolytes, and real indices of hydration during 11 days of controlled caffeine consumption. International Journal of Sports Nutrition and Exercise Metabolism, 2005;15:252-65.