Thursday, February 25, 2010

Supplements in Soccer – part IV (Caffeine)

Who has never heard of caffeine?? 
Well, probably, nobody!
That’s right, caffeine is a worldwide known substance that is present mainly in coffee, tea, chocolate and cola drinks. Normally, people consume these caffeine sources as a social drink or to keep eyes open in work/school… but did you know that caffeine is also the subject of a huge number of studies on exercise performance (including soccer performance)? That it is actually one of the most scientifically supported substances known to probably enhance your workouts?? Well, indeed, it is!

Effects of caffeine in soccer performance

Caffeine is a mild stimulant that increases the activity of the central nervous system, helping you stay alert and enhancing mental focus. Besides that, caffeine also causes an altered perception of effort or fatigue, so you’ll feel less tired! (Some scientists theorized that it would also cause a glycogen - the fuel of your muscles – sparing by increasing the fat burning, but this effect is short-lived or confined to certain individuals.)

How much caffeine is enough to achieve the desired results?

Small doses of caffeine (such as taken socially) may enhance performance, whereas high doses can be counterproductive to performance. Your target dose must be 1 to 3 milligrams per kilogram (0,5 to 1,5mg per pound), as found recently. This means that if you are a 70 Kg soccer player, you should take 70 to 210 milligrams of caffeine to perform better in the field.
Note that the effects of caffeine supplementation differ between individuals, according to their specific sensitivity and their previous exposure to the substance: if you are an occasional coffee (or other rich dietary source of caffeine) drinker, you’ll tend to be more sensitive to caffeine’s stimulant effects as compared with the daily coffee consumer who has developed a tolerance to caffeine.
Furthermore, you must understand that performance benefits don’t increase with increases in the caffeine dose.  In fact, caffeine doses in excess of 6-9 mg/Kg (approximately 400 -700 mg of caffeine) may cause you a variety of conditions: caffeine jitters, anxiety, stomach ache, bowel transit problems, increased heart rate, impairments of motor control and technique, disruption of sleep patterns and consequent impairment of recovery. As so, acute and long term intake of these large amounts of caffeine is generally discouraged by health authorities.

Table 1 provides you the average caffeine content of common sources.
If you are looking for a specific dose of caffeine, coffee isn’t the best choice when it comes to a well designed supplementation protocol, because of its great variability in caffeine content.

Table 1 - Average caffeine content in common sources. (Reprinted with permission from Nancy Clark, author of Nancy Clark's Sports Nutrition Guidebook, 4 Edition, 2008.)

Advised protocol of supplementation

Caffeine’s stimulant effect peaks in about one hour and then declines as your liver breaks down the caffeine (4 – 6 hours). This is the reason why traditional caffeine supplementation protocols consisted of consuming caffeine 1 hour before exercise. However, similar performance benefits may be seen if you split the initial dose into various doses across the exercise session: for example, take a partial dose 1h before match (ex: a latte) and the rest of it (ex: GU bar) at the interval.

Of course, forget about any protocol of caffeine intake if you don’t eat a balanced sports diet!

Cases where the use of caffeine is discouraged

Those who should abstain from caffeine or limit its consumption are:

  • Smokers;
  • Ulcer patients and others prone to stomach distress;
  • Athletes with anemia;
  • Pregnant women.

What about you? Have you ever supplemented with caffeine? How was your experience? Hope to hear from you!

Recommended reading for more information: 

  • Nancy Clark’s Sports Nutrition Guidebook (
  • Food Guide for Soccer: Tips & Recipes from the Pros   (

Diogo Ferreira, RD
Sports Nutritionist, Lisbon, Portugal
“Promoting best health and performance through nutrition”