More frequently (especially after long flights) I find myself heading to the break room for a pick-me-up, but more and more a single cup of Joe doesn’t get it done anymore. There are moments I’m struggling to keep my eyes open after 3 or 4 full cups of the caffeine goodness coming out of the coffee machine. Though my problem’s likely to be desensitization, research does indicate there is an optimal dose of caffeine.
Researchers from the University of Limburg in the Netherlands published findings on how different doses of caffeine affect athletic endurance. By administering 9 different doses of caffeine to well-trained cyclists (VO2max 65.1 + 2.6 ml · kg-1 · min-1), they analyzed how dose affects performance.
One hour after capsule ingestion, subjects cycled until exhaustion at 80 % Wmax on an electromagnetically braked cycle ergometer. Blood samples were taken before, during and after the exercise test. Before and after the test a urine sample was obtained.
Unsurprisingly they note that taking caffeine significantly improves endurance in at all dose levels. However, it doesn’t seem to matter how much caffeine is taken.
No differences were found in endurance performance between the three caffeine dosages which indicates that no dose-response relation of caffeine and endurance performance was found. An increased free fatty acid and glycerol concentration was found after caffeine consumption compared with placebo. It is concluded that caffeine is an ergogenic aid that stimulates endurance performance.
Notably only the lowest administered dose of caffeine tested below the legal doping limit set by the International Olympic Committee, advantageous since research indicates the lowest dose of 5 mg per kg body weight is equally effective at enhancing endurance.