Caffeine keeps some people up at night, even in small amounts, and makes others feel jittery.
But when consumed in moderation, this alkaloid compound – which abounds only in coffee, tea, and a few other botanical beverages – can enhance mental focus.
And caffeine can enhance people’s capacity for exercise and/or made it seem easier … although the evidence is mixed on both scores.
Caffeine may enhance performance or endurance by slowing the burning of stored glucose (glycogen) – thus keeping it available for later in an exercise session – and facilitating the burning of stored fat as a fuel source.
Its fat-burning effects – called thermogenesis – explain why caffeine has been used as a mildly, variably effective aid to controlling body weight and composition.
Caffeine may ease post-exercise pain
Judging by the outcomes of several small, controlled clinical trials caffeine appears to reduce the pain produced by exercise.
These trials have involved women and men, with most focusing on leg pain produced by cycling or exercise machines.
In most of these trials, the researchers tested doses ranging from 5mg to 10mg of caffeine per kilogram (2.2 pounds) of body weight.
And in most cases, the volunteers reported moderate pain reduction at the lower dose, with no greater pain reduction at the higher dose.
The lower dose translates to about 300mg of caffeine for a 150 lb person, which is the average amount in two to three cups of coffee or five to six cups of tea.
However, a newly published study seems to drop the effective dose substantially, to less than one cup of coffee, or about two cups of tea.
New trial affirms prior findings and determines a lower effective dose
The most recent study was a double-blind, placebo-controlled trial conducted among 10 students … five men and five women (Bellar D et al. 2011).
Scientists from the Walter Reed Army Institute of Research, University of Louisiana, and Ohio’s Kent State University set out to test the effects of caffeine on pain while college-age volunteers held weight plates at their side.
Half the volunteers chewed a piece of Stay Alert™ gum – which delivered about 85 mg of caffeine within five minutes – while others chewed an identical caffeine-free placebo gum.
The gum delivered an average dose of about 1.3mg per kilogram of body weight, which equates to about 75mg for a 150-pound person … and is less than half the lowest dose tested in prior trials.
The subjects’ ratings of perceived pain and exertion were recorded during the task every 15 seconds, until they could no longer maintain their grip.
No significant difference was found in endurance, but the volunteers who chewed the caffeinated gum reported significant cuts in pain, compared with the placebo group.
These results suggest that pain reduction may be achievable with a dose of caffeine equal to about three-quarters of one cup of coffee, rather than the two to three cups’ worth used successfully in earlier trials.
Caffeine may help beginners get past the initial pain
Caffeine’s apparent analgesic effect seems particularly relevant to people new to exercise, since they tend to experience the most soreness.
If you can use caffeine to reduce the pain, it may make it easier to get past the first week and continue into a durable exercise program.
Caffeine likely works by blocking cell receptors for adenosine … a chemical released in response to inflammation.
In fact, caffeine appears to be more effective in relieving post-workout muscle pain than several commonly used drugs.
Previous studies have found that the pain reliever naproxen (the active ingredient in Aleve) produced a 30 percent reduction in soreness. Aspirin produced a 25 percent reduction, and ibuprofen has produced inconsistent results.
UGA professor Patrick O’Connor made this point following a 2003 study: “A lot of times what people use for muscle pain is aspirin or ibuprofen, but caffeine seems to work better than those drugs, at least among women whose daily caffeine consumption is low.” (UGA 2007)
Of course, for some people, too much caffeine – even a little bit – can produce jitteriness, heart palpitations, and sleep problems.
And needless to say, for millions of other it's a welcome aid to getting going in the morning and focusing on the task at hand.
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