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Why caffeine (but not coffee) helps you run faster...
Caffeine - possibly the most popular drug in the world - is also
one of the most controversial. According to some, caffeine increases
your metabolic rate, making weight loss faster and easier. It's
also supposed to boost performance in the gym.
One common mistake is to assume that the effects of caffeine always
extend to caffeinated drinks such as coffee.
In fact, there is evidence to show that coffee does not have the
same effect as caffeine.
In a study carried out at the University of Guelph, researchers
attempted to distinguish between the effects of caffeine taken as
a capsule or in the form of coffee.
Subjects were assigned to one of five groups, and asked to run
on a treadmill to the point of voluntary exhaustion.
The first group received a placebo (a placebo is a "fake" supplement
used to reduce the influence of faith and belief in a treatment
on the results of a study).
Group two used caffeine capsules. The other three groups consumed
either coffee, decaffeinated coffee, or decaffeinated coffee with
caffeine added.
Interestingly, the researchers found no differences in run time
among the three trials in which coffee was ingested. The results
were no different from the placebo trial.
In sharp contrast, six of the nine subjects had their longest
run after taking the caffeine capsules, increasing their run time
to exhaustion by approximately 10 minutes.
In short, it appears that some component of coffee interferes with
the performance enhancing effects of caffeine.
This isn't surprising, considering that when coffee beans are roasted,
ground, and extracted in hot water, there are literally hundreds
of other compounds dissolved along with caffeine.
For example, a study in 1992 demonstrated that when one of these
compounds was injected into rats, it actually slowed heart rate
and lowered blood pressure, whereas caffeine has the opposite effect.
Reference
Graham, T.E., Hibbert, E., & Sathasivam, P. (1998). Metabolic
and exercise endurance effects of coffee and caffeine ingestion.
Journal
of Applied Physiology, 85, 883-889
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