Sections

Services

Information

UK United Kingdom

Health Check: does caffeine enhance performance?

Unlike many drugs, caffeine may be taken legally by people of all ages, which helps make it the world’s most widely used stimulant. Approximately 80% of the world’s caffeine is consumed in the form of…

About 80% of the world’s caffeine is consumed in the form of coffee. jennybach

Unlike many drugs, caffeine may be taken legally by people of all ages, which helps make it the world’s most widely used stimulant.

Approximately 80% of the world’s caffeine is consumed in the form of coffee; it’s been estimated that 500 billion cups of coffee are consumed throughout the world every year.

Tea, chocolate, cola drinks, and energy drinks and shots are the other main sources of caffeine.

Impact on physical performance

Caffeine has been used to good effect by athletes as an aid to physical performance for many years. Initially, it was believed to be of greatest benefit in endurance events (marathon running, for instance, or long-distance swimming).

More recently, we’ve realised that caffeine also boosts performance for short-term, high-intensity activities, such as middle-distance running, and stop-start sports, such as tennis.

Until a decade or so ago, it was thought that very high doses of caffeine (higher than could be obtained by simply drinking coffee, for example) were needed to enhance athletic performance.

Initially, caffeine was believed to be of greatest benefit in endurance events, such as long-distance swimming. Airman Magazine/Flickr

Such high doses could usually only be obtained from caffeine-containing capsules, and often led to adverse side effects.

Consequently, the International Olympic Committee (IOC) banned caffeine use by athletes above a certain level of intake.

But by early this century, it became clear that moderate doses of caffeine — achievable by drinking coffee, tea or energy drinks — were just as effective as very high doses for enhancing physical performance. And they had minimal risk of side effects.

It was also discovered that caffeine intake is “self-limiting” to some extent, that is, extremely high doses are likely to have a detrimental effect on athletic performance.

So, in 2004, the IOC ban on caffeine was completely lifted; Olympic athletes may now take as much caffeine as they like.

How much is enough?

What, then, is the most appropriate source of caffeine if you’re an athlete who wants to safely obtain a performance benefit?

The amount of caffeine in tea and coffee varies greatly. Ryan Hyde

Well, you could try coffee or tea, but the amount of caffeine in these beverages varies greatly. Energy drinks, on the other hand, are formulated to contain a known quantity of caffeine, so they allow for a more controlled intake.

A dose of about three milligrams of caffeine per kilogram of body weight will give you the desired boost to performance, with little likelihood of inducing the “caffeine shakes” that can result from overdosing.

So, for example, if an energy drink contains 80 milligrams of caffeine, and you weigh 55 kilograms, a couple of cans of energy drink will provide the recommended dose.

Some people believe that caffeine is a diuretic, that it promotes excessive urine production and therefore leads to dehydration. This is not correct, at least when caffeine is consumed in moderate amounts by habitual users.

People who regularly drink tea, coffee, cola drinks, energy drinks or energy shots can expect to receive the desired performance enhancement from caffeine without experiencing greater dehydration.

Making you sharper

There’s also evidence that caffeine improves some aspects of mental performance. Doses up to about 200 milligrams (similar to the dose that enhances physical performance) lead to increasingly quicker reactions, increased alertness, elevated mood and improvements in activities such as typing (greater typing speed with fewer mistakes).

The quantity of caffeine needed to enhance mental performance can be obtained by drinking one or two cups of coffee, one or two cans of energy drink, or several cups of tea. (But note the earlier advice that caffeine concentration is very variable in coffee and tea.)

Energy drinks are formulated to contain a known quantity of caffeine, so they allow for a more controlled intake. Nattu/Flickr

People who need to maintain vigilance during a period when they would normally be asleep, such as long-distance truck drivers, nightwatchmen, shift workers, students “cramming” for exams and soldiers on sentry duty, often use caffeine from coffee, tea, energy drinks and shots or capsules to keep them awake and alert.

The US Army now uses a commercially available caffeinated chewing gum called “Stay Alert” in one of its combat rations (the First Strike Ration). This ration is issued to soldiers who are expected to take part in operations of up to 72 hours with minimal sleep. Stay Alert gum contains 100 milligrams of caffeine per stick and there are five sticks in the First Strike Ration.

A little doubt

In the interests of objectivity, I should point out that a small minority of researchers believe that caffeine does not truly enhance mental performance. Rather, they claim that taking caffeine will simply overcome the drop in performance that results from caffeine withdrawal in people who are used to having caffeine in their body.

But looking at data from military studies I’m familiar with, I believe there’s little room for doubt that caffeine can greatly enhance at least some aspects of cognitive performance, particularly when people are sleep-deprived.

It’s important to keep in mind though that overdosing on caffeine is potentially dangerous, particularly for those (mostly young) people who consume too many energy drinks or shots – especially if they combine these with alcohol.

Caffeine undoubtedly enhances many aspects of physical performance, and very likely several aspects of mental performance too. And unlike most performance-enhancing drugs, it’s legal, readily available, and comes in forms that are highly acceptable to most people.

Join the conversation

11 Comments sorted by

  1. Michael Sheehan

    Geographer at Analyst

    Chris I haven't read a jot of the research on this, so forgive me if my question sounds stupid. Nowadays, I have one cup of coffee, first thing in the morning, seven days a week. Very, very rarely would I have two. If I had to complete some cognitive task at 9 am, without that coffee, I'm pretty sure, I'd be hopeless. But after that one cup, I tend to function fine all day long. OTOH, many years ago, I would have five or so cups a day at work, until I worked (via a professional) that those five cups were creating so much anxiety, and all sorts of other physiological strife, that my performance in all domains was being shot to pieces.

    report
  2. Onder Outluk

    logged in via email @fastmail.fm

    Every (recreational drug) in moderation works for me. For the effects of overdosing on coffee look no further than the USA - nuff said.

    report
  3. Paul Richards

    integral operating system

    Appreciate any article on caffeine.
    Chris Forbes-Ewan wrote; "... keep in mind though that overdosing on caffeine is potentially dangerous" The most obvious issue with any drug is dosage. Each individual using awareness can adjust their caffeine dose to suit their physiology. Common sense really. Still those with unevolved value systems need guidance and that includes adults who have not grow up.

    report
  4. David Oakenfull

    food scientist

    Is this really an ad for Redbull? (See 4th picture from the top.) I agree that there's plenty of evidence that caffeine can enhance performance for elite athletes. But where's the evidence that caffeine can help the average runner or cyclist? There is none.

    Caffeine-loaded energy drinks are also loaded with sugar which means they're both fattening and useless for rehydration. What's more they're marketed to appeal to young kids for whom caffeine can be dangerous (as the author correctly points out.

    report
    1. Sue Ieraci

      Public hospital clinician

      In reply to David Oakenfull

      Hi, David.

      We discussed on TC before the difference in consumption styles and patterns between coffee and cold, sweetened, caffeinated beverages.

      Hot coffee - with or without milk, is not considered to be a children's drink - most kids don't like it until they are at least teenagers. And hot coffee is not generally ''slammed down'' - the temperature would prevent this.

      Contrast the cold, sweet caffeinated beverage, which tastes good to kids, and can be guzzled down in one long swallow. Different taste, context and appeal.

      report
  5. Gary Cassidy

    Monash University

    This article has nothing to do with health. Sports or military performance (or performance enhancement) is not a measure of health at all.
    It is a shame because the previous "Health Check" articles have been quite good and related to health.
    The article also "promotes" energy drinks for their caffeine content without providing a broad context of positive/negative associations of energy drink consumption and health outcomes.
    RE: "you weigh 55 kilograms, a couple of cans of energy drink will provide…

    Read more
    1. Chris Forbes-Ewan

      Senior Nutritionist at Defence Science and Technology Organisation

      In reply to Gary Cassidy

      Gary Cassidy wrote: 'This article has nothing to do with health'.
      I can't disagree with that comment. However, the brief I received required me to write an article about caffeine and performance ... so I did.
      Gary also wrote: 'The article also "promotes" energy drinks for their caffeine content without providing a broad context of positive/ negative associations of energy drink consumption and health outcomes.'
      As mentioned above, the brief requested that I discuss caffeine and performance ... so I did! I had about 800 words to do so. I did mention the potential for adverse health effects, but this article was primarily concerned with performance effects.
      If you would like to read about the likely effects of caffeine on health, I suggest you read the transcript of my Ockham's Razor program on this subject at the following tinyurl:
      http://tinyurl.com/6ur9b3c

      report
    2. Gary Cassidy

      Monash University

      In reply to Chris Forbes-Ewan

      Hi Chris,
      Thanks for the clarification. Although I found the article informative, it is a shame that the editors chose to include it in the "Health Check" series and not in a "high performance" series or stand alone article.
      Thanks for the link to the Ockham's Razor program - very informative.

      report