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Caffeine and Performance

The daily fix or the ergogenic aid?

The morning brew is pretty damn important to some of us.  There is not much better than a well crafted cafe to start the slog.  For the day-to-day man it makes the commute bearable and the first few emails a breeze, but there is also good evidence that caffeine is both safe and possibly beneficial for performance in athletes.

Caffeine is a stimulant.  That is why we crave it and why it makes the morning more pleasant.  It also changes your perception of events and one important perception is that of effort.  Not only does that mean we can get through the morning with minimal fuss but this is also why it assists athletes perform harder, changing their perception from “are you crazy?” to “one more rep”.  The most promising results shown in most research is that of improvements in endurance performance but the benefit also extends to other mixed-type events (team sports) as well as short, high intensity sports (middle distance events) lasting 1-60 minutes too.  There does not appear to be any benefit for strength and power events however.

To summarise a review article by Louise Burke:

  • the mechanism of action is poorly understood
  • caffeine enhances endurance performance over a range of protocols
  • caffeine can be ingested before or during exercise or after the onset of fatigue
  • benefits occur at 1-3 mg/kg body weight with little or no dose-response relationship
  • some people are non-responders
  • withdrawing from caffeine to maximise its effect may occur over 24-48 hours but this effect is unproven
  • dosages as high as 6-9 g/kg body weight may have adverse effects
  • the effect of caffeine may last up to 6 hours with individual variances

Caffeine was previously a banned substance but has since been removed from the World Anti Doping Agency (WADA) list. This decision was taken due to caffeine being a commonly consumed compound in a regular diet and the fact that it has no adverse health effects at normal doses. However high doses of caffeine (10 mg/kg body weight) can cause adverse effects such as heart palpitations, diarrhea and cramping, particularly to those who are sensitive to the stuff. Adults who do not consume caffeine in their diet should not aim to use caffeine as a supplement and anyone under the age of 16 should avoid excess dietary intake of caffeine.

While a dose-response is small it seems as though the performance benefit of caffeine plateaus at around 3 mg/kg and a safe recommendation is thus 1-3 mg/kg, split it into a pre-exercise and mid-exercise dose. For a 70 kg athlete this would be around 70 mg before exercise and 70 mg toward the point where you know things get difficult.

We do also get responders and non-responders to caffeine supplementation which means that it might not work for everyone.  At these dosages, however, it is safe to try and see the effects for yourself.  Make sure you try it in training first though, not at 6h30 on the morning of the Argus.

The jury is still out on the effect caffeine might have on recovery from exercise.  The concern here is the link to sleep deprivation, dehydration and altered glucose metabolism that are all important aspects of recovery and impact glycogen replenishment in the muscles.  Research does suggest that altered sleep quality is linked to the responder and non-responder issue and the dehydration and altered glucose metabolism may be less of an issue than first thought.

Coffee, or most foods for that matter, are not a great way of supplementing as the values vary greatly but food sources are a safer bet than commercial products in terms of safety for athletes. Some products like gels and bars from Gu or Hammer have caffeine added and listed.  The good old “Regmaker” is a caffeine pill that provides 150 mg per serving.

Common sources of caffeine are listed below.

Food/BeverageServing sizeCaffeine content (mg)
Instant coffee250 ml60  (may be 15-150mg)
Brewed coffee250 ml80  (may be 40-110mg)
Espresso35ml110 (may be 25-210mg)
Tea250ml30 (may be 10-50mg)
Dark chocolate60g10-50
Red Bull250ml80
Scheckters Energy Drink*250ml85
GU sports gel32g sachet20

*Scheckters Energy Drink is Informed Choice approved and safe for use by athletes

For more on the safety and efficacy of supplements READ HERE. Consult your health practitioner or specialist before using any supplement.

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6 Responses to Caffeine and Performance

  1. jamie Feb 15, 2012 at 6:54 pm #

    Red bull gives you wiiings! Penz enegry drinks? Can they really help you? What is too much intake etc! People mix them with booze etc what effects does this have, does it counter against the booze? Is that the caffeine etc

    • Adi Feb 15, 2012 at 10:33 pm #

      Ja skwee. Energy drinks help purely because they give sugar for energy and caffeine for improved perceptions. Mixed with alcohol though they are dangerous because the alcohol is a depressant and the caffeine a stimulant. They don’t cancel each other out but the caffeine makes one think they are fine or less drunk than they actually are by blunting their perceptions. Too much with booze should be avoided. Too much on its own would be more than about 5 cans roughly. A caffeine dose of 6mg/kg brings about adverse reactions..

  2. shawzaloza Jun 21, 2013 at 3:19 pm #

    Apparently George Gregan was a big advocate for taking a few caffeine pills before training.
    What is your take on Green tea? There are plenty rumours about it having more caffeine than coffee. I am under the impression that Green tea actually mimics the effect of caffeine. From my experience, I feel a greater sense of energy/awareness after drinking green tea (much more so than coffee).

    • Food For Sport Jun 21, 2013 at 3:46 pm #

      There are quite a few varieties of green tea and as such they have varying levels of caffeine. It is quite possible that some are higher than coffee, particularly coffee that is in the lower range of caffeine content.

      The other thing to green tea is that it also contains other polyphenols that may have various effects..

  3. Nick Jun 24, 2013 at 10:29 am #

    Interesting post Adi! I really enjoyed it. I’m going to look for a green tea with high caffeine to see if it makes the morning push easier. Do you know of any at the moment? If not, I’ll let you know when I find some…

    • Food For Sport Jun 24, 2013 at 4:43 pm #

      Any natural product will vary but green tea will give an average of 25-75 mg per cup. Brewing it longer or using some powdered ones are likely to increase caffeine content. Apparently Matcha Green Tea is higher in caffeine content??