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Caffeine is the world’s most commonly used performance enhancing drug. For many of us, it enhances us up out of our beds in the morning, and it’s well known as ‘wake-up juice.’
First, what is caffeine, and what does it do at the basic level?
Caffeine is a stimulant drug that imitates the effects of epinephrine, or adrenaline, in the brain and body. Technically it’s a bitter white alkaloid, which explains the appalling taste of caffeine diet and ‘stay-awake’ pills. In the brain, caffeine attaches to the same receptors as a chemical called Adenosine. Adenosine is a chemical that has several jobs in the brain, but one of them is to make you feel tired. As a result, when caffeine binds to these receptor sites it prevents you feeling tired.
Caffeine keeps you awake by both binding to adenosine sites and by increasing the rate at which your synapses fire. But there’s more to caffeine than wakefulness.
Some people are dubious as to caffeine’s status as a performance enhacing substance, but Dr. Mark Tarnopolsky of McMasters University, Canada, isn’t one of them.
‘There is so much data on this that it’s unbelievable,’ he told the New York Times in 2009. ‘It’s just unequivocal that caffeine improves performance. It’s been shown in well-respected labs in multiple places around the world.’
For some time, the main mechanism by which caffeine improved sports performance was thought to be its effects on fat burning. Caffeine tends to help muscles use fat as a fuel, meaning that more glycogen is available for longer, which would tend to improve performance in endurance events. This explanation dates back to the origins of research into caffeine as a sports supplement in the late 1970s. But it wouldn’t explain the effect, documented anecdotally and in tests, that shows caffeine enhancing performance at sports that aren’t endurance based at all.
How can fat burning make you a better sprinter? Could it be the placebo effect?
Perhaps, but Dr. Tarnopolsky’s research indicates that caffeine increases power by triggering the release of calcium stored in muscle tissue. This effect can enable improvements in both endurance and in strength and power, and Dr. Tarnopolsky’s team saw improvements in the 20 to 25% range in laboratory conditions. The real world improvements are thought likely to be less than this, probably in the 5% region, though this would still be a significant bump for athletes working to shave a few seconds off their times or squeeze a few more pounds on the bar.