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Pearls and Pitfalls

Sports Medicine Pearls and Pitfalls

Java Jolt

Eichner, E. Randy

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Current Sports Medicine Reports: March 2009 - Volume 8 - Issue 2 - p 42-43
doi: 10.1249/JSR.0b013e31819c79d0
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Caffeine, a stimulant that may date back to the Stone Age, is one of the world's most common drugs and long has been used by athletes. Among the early athletes to use caffeine as an ergogenic aid were the dervishes who, in the Middle Ages, quaffed java to extend the whirl and enhance the trance (4).

Research on caffeine for sports goes back more than 100 yr, but the pre-event java-drinking fad began in earnest in 1978 when esteemed exercise physiologist David Costill, Ph.D., told Runner's World magazine that caffeine could speed marathon running by 10 min. This led to long coffee lines and longer restroom lines at marathons. In 1984, the U.S. Olympic cycling team experimented with a novel delivery system for caffeine: rectal suppositories (4).


The caffeine fad soon was fed by researchers who found that runners performed better in a laboratory test after large doses of caffeine (9 mg·kg−1), about equal to six cups of strong coffee. In a double-blind, placebo-controlled study, caffeine consumed 1 h before "race pace' exercise increased running time to exhaustion by 44% and cycling time to exhaustion by 51% (7). Further studies in the same laboratory found lower doses of caffeine (3-6 mg·kg−1) also to be ergogenic and that, insome subjects, the side effects from higher doses (nausea, anxiety, jitteriness, dizziness) impaired performance. In a similar study, smaller improvements in cycling time (approximately 27%) were seen at each of three doses, 5 mg·kg−1, 9mg·kg−1, and 13 mg·kg−1 caffeine (14). In other studies, caffeine improved performance in a 1-h cycling time trial (12), sped runners by 1.2% in an 8-km field run (1), improved cycling-ergometry performance by 4% at doses as low as 2 and 3 mg·kg−1 (9), improved performance in a simulated rugby game (17), and even enhanced endurance (in cycling and in isometric arm flexion) in 75-yr-old citizens (13).

How caffeine enhances endurance remains unclear. Part of the boost may be from glycogen sparing early in exercise, which may stem in part from enhanced fat oxidation. Caffeine can boost plasma epinephrine. Caffeine also can reduce leg-muscle pain during high-intensity exercise (6). Maybe most importantly, caffeine increases alertness, improves mood, and reduces perceived effort, so the exercise just seems easier and the athlete goes longer.


Caffeine also can improve "middle-distance" performance. It can shave a few seconds off the 1500-m treadmill running time of club runners who can run a mile in approximately 5 min (18). It can speed a 1500-m swim that takes approximately 20 min or a 2000-m simulated rowing time trial that takes approximately 7 min (2,11).


It seems that caffeine also can improve sprint or anaerobic performance. Early studies showed little or no ergogenic effect of caffeine in repeated brief bouts of intense cycling exercise (30-s Wingate tests) or in repeated 20-s running sprints (8,15). But one early study did suggest a modest benefit from caffeine in sprint swimming (3). Recent studies build upon this theme. In one study, caffeine led to more weight lifted in a chest press and more peak power generated in a Wingate test (20). In another study, caffeine increased speed and power in a 1-km cycle-ergometer time trial (19). In a third study, when 21 men ran 30-m indoor sprints, caffeine led to faster times in the first 3 of 12 such sprints (5). It seems, then, that caffeine may benefit both single and multiple sprint sports.


In 2008, an NCAA female athlete tested positive for caffeine (>15 mcg·mL−1 in urine) after her event and lost eligibility time even though she purportedly drank only a modest amount of coffee and one or two energy drinks pre-event. This raises concern, especially in light of the increasing popularity of caffeine-laced "energy drinks."

Among the drugs we humans tend to get hooked on, caffeine is one of the safest. Rare human fatalities have occurred, but they take a huge overdose, in excess of 5 gm, or the amount in 50 cups of strong coffee (10). A sad example was reported in USA Today in 1998, a 20-yr-old college student who took most of a 90-pill bottle of caffeine pills on a dare and soon died from cardiac arrhythmia.

Then, too, some folks can tolerate prodigious amounts of coffee. Vincent van Gogh drank 23 cups during a painting high. Pearl: The world record was set in 1927 by a Minnesota porter named Gus Comstock. In just over 7 h, Gus drank 85 cups of coffee. Near the end of his colossal coffee-quaff, amid a cheering crowd, "His gulps were labored, but a doctor found him in pretty good shape." How Gus slept that night is lost to history.

But back to college athletes on caffeine. In a football game, two cornerbacks took a supplement containing 120mg caffeine. In the first quarter, both came out of the game, jittery and queasy. One was giddy, the other felt "weird in the head." The caffeine buzz was unpleasant and impaired their performance. Pearl: Caffeine in sports can do more harm than good. And no sure formula exists to tell athletes how much caffeine is "safe."

Another point is that striking individual differences exist in caffeine metabolism, largely genetic. Caffeine is metabolized mainly by cytochrome P450 1A2 (CYP1A2), and those who carry the common variant CYP1A2*1F allele are "slow" metabolizers (16). In addition, women tend to metabolize caffeine more slowly than men do, and certain drugs, like birth control pills, slow caffeine metabolism.

So the college female athlete who was born a slow metabolizer and who is taking birth control pills may be set up to test positive (by NCAA standards) after consuming only a modest amount of caffeine. This is not fair. It may be time to reassess caffeine use by college athletes - and whether and how to test for it.


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Copyright © 2009 by the American College of Sports Medicine.