Caffeine is a stimulant and is used in many thermogenic formulas
to increase metabolic rate. Caffeine also increase fat breakdown and
use of fat as a fuel during rest and exercise. In terms of athletes,
there exists a large number of studies that have evaluated the effects
caffeine on prolonged endurance performance. Several studies show
greater use of fat as a fuel, sparing of glycogen use during exercise,
and enhanced endurance performance. However, there are fewer studies
examining short-term exercise performance such as sprinting. One study
had athletes perform repeated sprints one hour after either caffeine
ingestion or placebo. The dose of caffeine was 6 mg/kg body weight
(about 450-500 mg of caffeine) which is equivalent to 3-4 cups of
brewed coffee. Times during 5 sets of 6 x 20 m sprints were
significantly faster after caffeine and reaction times, and there was
also a trend for improved reaction times. The findings indicate that in
addition to prolonged endurance performance, acute caffeine ingestion
can also significantly improve sprint performance.
Carr A, Dawson B, Schneiker K, Goodman C, Lay B. Effect of caffeine
supplementation on repeated sprint running performance. J Sports Med
Phys Fitness. 2008 Dec;48(4):472-8.
