The fact is, caffeine works. Although not all studies have shown the effects of caffeine on endurance performance, most well-conducted studies have shown an improved endurance capacity after ingesting caffeine at a dose of 3mg/kg to 9mg/kg, says leading sports nutritionist Dr Asker Jeukendrup…

For a 70kg person this is 210-630mg of caffeine or, put more simply, two cups of strong coffee. At exercise intensities of 85% of maximum oxygen uptake improvements of 10-20% are typically found for the time people can last until they are exhausted. Caffeine also decreased perceived ratings of exertion, meaning people found it easier to exercise after caffeine. Interestingly, studies have proved that habitual caffeine users performed similarly to those who didn’t use caffeine, and so there’s no reason to abstain from caffeine in the run-up to a race.

Triathlon Nutrition - CaffeineHow we use caffeine

Blood levels rise and peak around one hour after taking caffeine. The half-life is between two and 10 hours, which means caffeine levels stay high for a fairly long period of time. This means caffeine should be ingested one hour before exercise to get optimal effects and very few top-ups will be needed during prolonged exercise. Caffeine can be ingested in various forms, but gels and bars are convenient during a race. But be warned – caffeine can also produce side effects like gastro distress, headaches, an increased heart rate, restlessness, elevated blood pressure and is also a diuretic, which will increase your dehydration on race day.

Caffeine culprits – just how much of the drug is in your favourite drink?

  • 1 cup of brewed coffee – 91mg
  • 1 sachet Science In Sport Energizer Gel – 83mg
  • 1 bottle Lucozade Sport Caffeine Boost – 80mg
  • 1 can Red Bull – 80mg
  • 1 shot espresso – 77mg
  • 1 can Diet Coke – 42mg
  • 1 can Pepsi – 35mg
  • 1 can Coca-Cola – 33mg