19th May 2016
Many sports supplements make bold claims about boosting performance but only a few are backed up by credible research. In the third article of this 5-part series on supplements, I look at the evidence for caffeine.
What is it?
Caffeine is a stimulant that’s legal, relatively safe and found in many everyday foods and drinks. It was once classed as a banned substance but was removed from the World Anti-Doping Agency (WADA) Prohibited List in 2004. This change was based on the recognition that caffeine enhances performance at doses that are indistinguishable from everyday caffeine use.
What does it do?
Caffeine acts on the brain, blocking a sleep-inducing brain chemical called adenosine. So, instead of feeling tired, you feel more alert and energetic, you react faster and you don’t feel like you’re working so hard. It may also enhance the ability of muscles to contract.
What’s the evidence?
Caffeine is one of the best-tested supplements and the vast majority of studies have found that it enhances both endurance exercise as well as short-term higher-intensity exercise performance (shaving an average of 3% off of athletes’ finish times) and makes exercise seem easier. Three percent is about 2 minutes an hour.
In a study published in 2016, University of Guelph researchers found that cyclists who consumed caffeine mid-way during a 2-hour cycle challenge went on to complete a time trial significantly faster than those who took a placebo. In a 2009 study at the University of Texas, cyclists who consumed caffeine in the form of an energy drink completed a 1-hour time trial 3 minutes 4 seconds faster than those who took a placebo.
A study at the University of Saskatchewan found that consuming caffeine in amounts equivalent to 2 mg caffeine/kg of body weight one hour before exercise significantly increased bench press muscle endurance. Another study with footballers found that consuming a caffeinated drink one hour before training improved sprinting performance and reduced the perception of fatigue.
However, caffeine may be less beneficial for those doing strength and power sports, such as weight lifting or a single sprint, according to the position stand of the International Society of Sports Nutrition but it may help with sports involving repeated sprints, such as football.
Verdict (How much and when)
If you’re looking for an easy way to increase your stamina you could do worse than drinking a cup of coffee before a workout.
Caffeine is one of the few supplements that may actually help you exercise longer and harder. You only need 1–3 mg/kg to get a performance boosting effect, which is less than once believed (6 -9 mg/kg). For a 70 kg person, this would be 210 mg, equivalent to a double expresso, 2 – 3 gels or 2 cans of energy drink .
Don’t use it for every workout (habitual use may reduce immune cells). Save it for when it matters most: race day. For best results, take it 30 – 60 minutes before your event starts. It stays in your bloodstream a long time – it’s half life is around 5 – 6 hours, meaning that you’ve only managed to clear half of it out of your body by then. For events longer than 2 – 3 hours, you may prefer to take it during the latter stages as fatigue is beginning to occur.
It makes little difference to performance whether you take your caffeine in the form of pills, gels, energy drinks or coffee, according to a 2015 review of studies by University of Georgia researchers.
It’s a myth that that caffeine dehydrates you – researchers found no difference in hydration status between athletes consuming caffeine or placebo during exercise.
Individual responses vary, and not everyone performs better with a caffeine boost. Take too much and you might just end up feeling nauseous, or suffering caffeine jitters at a time when you are already nervous and anxious. Experiment in training, not on race day, to find the dose and protocol that suits you – or even whether plain water is your best bet.
Caffeine is not recommended for athletes under 18. It’s not been tested with this age group and, although energy drinks are popular among this age group, teens are more likely to suffer side effects such as headaches, nausea and trembling.
If you enjoyed this article and want to find out more about sports supplements, then read the new edition of my book
Sports Supplements – Which nutritional supplements really work
Fully updated to reflect the latest research, Sports Supplements is packed with clear, reliable and unbiased advice that will help you maximise your athletic potential. Renowned sports nutritionist Anita Bean takes you through each supplement and explains what they are, how to use them and if they really work – as well as suggesting other alternatives.
Covering the most popular supplements on the market – from beetroot juice to creatine, caffeine to whey protein, this is the essential guide for anyone considering taking supplements.