Even if you’re much fitter than ordinary mortals, caffeine can still boost your endurance performance. Sports scientists at California State University San Marcos discovered that caffeine has a stimulatory effect on people, no matter what their level of fitness. Caffeine is one of the better-researched supplements. Studies have shown that the compound boosts your fat burning, as well as your sprint and endurance capacity [J Sci Med Sport. 2008 Apr;11(2):231-3.] – and possibly also your strength.
Nevertheless caffeine has a bad image. Better athletes tend to turn their nose up at the idea: such a common-or-garden substance can’t possibly work, is their attitude. But according to the human study that the Californian researchers published in 2011 in the Journal of Caffeine Research, they’ve got it totally wrong.
The researchers did an experiment with eight reasonably fit [active] and eight super-fit [endurance] athletes. All of the subjects trained almost daily. Those in the active group either took part in team sports, or they did cardio or weight training. They were fit, but had less stamina than the runners, cyclists or triathletes in the endurance group.
The researchers got their subjects to do a timed cycle ride of 10 km in a laboratory. On one occasion the athletes were given a placebo, on two other occasions they got a sports drink containing 5 mg caffeine [structural formula shown below] per kg bodyweight. They took the supplement an hour before starting to cycle.
The researchers discovered that almost all the athletes reduced the time of the ride by amounts between 0.3 and 2.0 percent when they had taken caffeine, regardless of how fit they were. Only one athlete performed less well after taking caffeine.
There were mild side effects. Some athletes felt uncomfortably hyper; others had the shakes or became nauseous. On the other hand though: only 31 percent of the subjects were able to tell whether they had been given a placebo or the drink containing the active ingredient.
Journal of Caffeine Research. September 2011, 1(3): 179-185.