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Reuters is reporting on a newly published article in Neuropsychopharmacology (a pretty cool journal name, I must say) about habitual caffeine use:
Bristol University researchers found that drinkers develop a tolerance to both the anxiety-producing and the stimulating effects of caffeine, meaning that it only brings them back to baseline levels of alertness, not above them.
“Although frequent consumers feel alerted by caffeine, especially by their morning tea, coffee, or other caffeine-containing drink, evidence suggests that this is actually merely the reversal of the fatiguing effects of acute caffeine withdrawal,” wrote the scientists, led by Peter Rogers of Bristol’s department of experimental psychology. [The study is described in more detail here.]
This caught my attention (a) because I don’t drink coffee and I enjoy making fun of my wife’s addiction, and (b) because I’ve seen conflicting information about whether habitual coffee drinkers get less of a boost from each cup. I spoke to Terry Graham from the University of Guelph, one of the world’s top experts on the effects of caffeine, for this article back in 2008. He said that, as far as sports performance goes, habituation isn’t a problem:
Surprisingly, the same performance boost from caffeine is seen in regular coffee drinkers and in complete abstainers. We do habituate to some of caffeine’s effects, such as elevated pulse and blood pressure, but apparently not to its performance-enhancing effects.
That finding was backed up by another study last year on the effect of caffeine on pain perception during intense 30-minute cycling sessions, by Robert Motl of the University of Illinois:
“What’s interesting,” Motl said, “is that when we found that caffeine tolerance doesn’t matter, we were perplexed at first. Then we looked at reviews of the literature relative to caffeine and tolerance effects across a variety of other stimuli. Sometimes you see them, sometimes you don’t. That is, sometimes regular caffeine use is associated with a smaller response, whereas, other times, it’s not.”
No one’s been able to figure out the reason for the inconsistency, Motl said.
“Clearly, if you regularly consume caffeine, you have to have more to have that bigger, mental-energy effect. But the tolerance effect is not ubiquitous across all stimuli. Even brain metabolism doesn’t show this tolerance-type effect. That is, with individuals who are habitual users versus non-habitual users, if you give them caffeine and do brain imaging, the activation is identical. It’s really interesting why some processes show tolerance and others don’t.”
Regarding the outcome of the current research, he said, “it may just be that pain during exercise doesn’t show tolerance effects to caffeine.”
So it seems that for enhancing sport performance, it doesn’t really matter whether you use caffeine regularly. But that boost you get every morning — well, that’s not really a boost, it’s just a return to normal.