In a study of competitors at the Ironman Triathlon World Championships, 73% of the athletes interviewed reported that they used caffeine in an effort to improve their performance on course, and 84% reported that it improved concentration. Yet, many of these same athletes didn’t know how much caffeine they needed to improve their performance, or the caffeine content of common foods and beverages.
Are you up on the latest thinking on caffeine, and do you have a caffeine intake strategy to effectively improve your athletic performance?
Caffeine 101
1,3,7-trimethylxanthine, aka caffeine, is the world’s most-consumed natural pharmacologic agent. Caffeine is found in coffee beans, tea leaves, cocoa beans, chocolate, and cola nuts, and its use is incredibly widespread. In the United States, roughly 9 out of every 10 men and women consume caffeine, averaging 238 mg every day. Upwards of 30% of Americans consume a whopping 600 mg of caffeine daily. About 71% of the caffeine we consume comes from coffee, while 16% comes from tea, and 12% from soft drinks and energy drinks. And we are not alone. Coffee is the most-commonly consumed beverage in the world.
So, let’s acknowledge the obvious. First, just about everyone is using caffeine. In fact, because of its ubiquitous availability, caffeine is no longer on the banned substance list of the International Olympic Committee. Second, people everywhere are using it because it does have pharmacologic properties. The fact is it functions as a mild stimulant. As such, it helps wake us up and keeps us going when we feel like throwing in the towel. No surprise, athletes are interested in those very same effects applied to their sport.
Does it Work?
The data are pretty convincing that caffeine is effective at improving athletic performance for a number of sports. Caffeine has been shown to improve endurance and time trial performance in cyclists, improve endurance in runners, and improve performance times and power in rowers. It also has been shown to boost performance in intense short-term cycling and running events lasting 5 minutes, and to increase peak power output, speed, and isokinetic strength in sprint and power events lasting less than 10 seconds. Researchers studying tennis players found that caffeine increased hitting accuracy, speed and agility, and overall playing success on the court. And players reported feeling more energy late in their matches.
Thus, it seems to work for a number of sports and events, but it doesn’t help in all cases. For example, caffeine has clearly been shown to have no effect, and may even be a negative factor, in sprint and power events lasting anywhere from 15 seconds to 3 minutes.
How Caffeine Works
Caffeine has a wide range of actions in the human body, including hormonal, metabolic, muscular, cardiovascular, kidney, and respiratory effects. Caffeine also works on the central nervous system. It functions as a stimulant by interfering with the binding of adenosine to adenosine receptors. Adenosine is a neuromodulator chemical in the brain, and it works opposite of caffeine in regulating nerve cell activity. Adenosine has a calming effect because it slows the activity of nerve cells, whereas caffeine speeds up the activity of cells. Through its effects on the central nervous system, caffeine intake decreases tiredness, increases alertness, improves mood, confers a sense of being energized, enhances concentration, and helps to speed reaction time when making choices.
How caffeine’s hormonal, metabolic, physiologic effects, and central nervous system effects work together to improve performance remains a matter of study. However, one thing is clear. For many athletes, a key benefit of caffeine is that it lowers the perception of the intensity or difficulty of the effort. Thus, athletes are able to exercise at a higher intensity for longer, without actually feeling like they’re working harder.
Caffeine Dose
All athletes want to know the amount of caffeine required to improve athletic performance.
And it turns out that a moderate dose is all that’s needed. Moreover, there’s no evidence that additional caffeine provides any greater performance benefit. In fact, higher doses are more likely to cause unwanted side effects.
The more recently recommended caffeine dose for performance improvement is 1-3 mg caffeine per kg body weight (0.45-1.4 g per lb). For a 68 kg (150 pound) athlete, that equates to a range of about 70-210 mg of caffeine.
When caffeine intakes get in the 9 mg per kg body weight (4 mg per lb), there is an increase in side effects like jitteriness, nervousness, insomnia, headache, dizziness, and gastrointestinal distress, which can obviously have a detrimental effect on performance.
Tolerance and Withdrawal
Recommending a caffeine intake level doesn’t tell the full story. Tolerance and withdrawal symptoms need to be considered.
If you are new to caffeine, you’ll experience a noticeable buzz or jolt the first time you consume a moderate dose of the stuff. But if you take that same caffeine dose every day, by about day 5 or 6, the stimulant effects are much less obvious. This is because you develop a tolerance or diminished response to caffeine with repeated doses.
The other side of the tolerance coin is withdrawal. Once you grow used to a certain daily intake of caffeine, abrupt withdrawal can lead to symptoms, the most common noticeable one being a bad headache. Less obvious is that withdrawal can have a detrimental impact on athletic performance. Symptoms peak in a day or two and are usually completely gone within 4 to 7 days. Fortunately, if you resume caffeine intake in the midst of withdrawal, the symptoms, including headache, usually disappear pretty quickly.
Realizing that tolerance and withdrawal are issues, factor them into your caffeine usage strategy:
- If you are a caffeine novice, you can use caffeine to get you through 3 or 4 days of intense workouts prior to an important competition. Do this by starting with a low dose of 1-2 mg caffeine per kilogram body weight (0.45-0.9 mg per pound), and then increase the dose a bit each day to achieve the same effect.
- If you’re a regular caffeine user, and want to get its full effects during a competition, gradually reduce your caffeine consumption over 3 to 4 days to avoid withdrawal symptoms. Do this at least 1 week before the competition to be completely free of withdrawal effects. Once you are off caffeine, resume a moderate intake of 1-3 mg caffeine per kg body weight (0.45-1.4 mg per pound) on the day of your competition. This will result in the desired stimulant effects again, just like in a nonuser.
Timing of Caffeine Intake
Caffeine is readily absorbed by the gastrointestinal tract. The concentration in the bloodstream peaks in 30 to 60 minutes and stays high for 3 to 4 hours. On average about half of it is gone within 4 to 6 hours, and 75% is cleared within 6 to 7 hours. Therefore, your window of opportunity to derive a performance benefit from caffeine is probably about 4 hours from the time you consume it. In addition, consuming caffeine about an hour before your event will help to ensure that blood levels are high when you begin competing.
You don’t need to consume all your caffeine pre-exercise. Studies have compared taking a full dose of caffeine an hour before exercise, to half the dose an hour before and the other half 45 minutes into exercise. Both regimens improved performance times similarly in comparison to a control. Another study compared taking the full amount of caffeine an hour before exercise, to taking the caffeine in divided doses every half hour during exercise. Here again, both regimens improved performance times similarly.
Putting this into practice, if you weigh 68 kg (150 lbs) and require 2 mg caffeine per kg body weight (0.90 mg per pound) for your 2 hour event, the 136 mg can be taken all at once an hour before competing, or it can be taken as about 25 mg caffeine every half hour starting 60 minutes before the competition.
Caffeine Sources
Although coffee is the most widely consumed caffeine source, it may not be the best source for improving athletic performance. First, you can never quite be sure what level of caffeine you’re getting in a cup of coffee or a prepared coffee drink because of the inherent variability in coffee sources and differences in preparation methods. Second, there may be something in coffee that antagonizes or impairs the ergogenic effects of coffee. In a study of treadmill runners, endurance times were increased when athletes were given a standardized dose of caffeine, but not when given that same dose in the form of coffee. An advantage of energy gels and cola drinks that are often available at aid stations during events, is that the caffeine dosages in these products are more uniform and dependable. This can be helpful in ensuring that you get the caffeine dose you know to be effective.
Beverages are common and often the most concentrated sources of caffeine, but amounts vary considerably between beverages as shown in the table below. There is also large variability within beverage categories, especially for coffee and energy drinks. POWERBAR energy gels and energy chews are available with and without caffeine. These sports nutrition products can be used to help meet your caffeine and fuel needs prior to or during exercise.
| Beverage or Food |
Serving Size (fl oz) |
Caffeine Content (mg/serving) |
| Cola beverages |
12 (360 mL) |
35–55 |
| Iced tea, instant |
12 (360 mL) |
25–30 |
| Flavored teas |
12 (360 mL) |
30 |
| Tea, brewed |
8 (240 mL) |
40–60 |
| Tea, green |
8 (240 mL) |
15 |
| Hot cocoa |
8 (240 mL) |
15 |
| Coffee, drip |
8 (240 mL) |
115–175 |
| Coffee, brewed |
8 (240 mL) |
80-135 |
| Coffee, instant |
8 (240 mL) |
65-100 |
| Coffee, espresso |
2 (60 mL) |
100 |
| Energy drink |
8 (240 mL) |
80-300 |
| POWERBAR® GEL varieties – Chocolate, Green Apple, Strawberry Banana flavors |
1 packet |
25 |
| POWERBAR® GEL varieties – Double Latte and Tangerine |
1 packet |
50 |
| POWERBAR® GEL Blasts – Cola |
6 pieces |
50 |
Sokmen B, Armstraon LE, Kraemer WJ, Casa DJ, Dias JC, Judelson DA, Maresh CM. Caffeine use in sports: considerations for the athlete. J Strength Conditioning Res 2008;22:978-986.
Desbrow B. Leveritt M. Well-trained endurance athletes’ knowledge, i
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