Caffeine and Exercise Performance - Caffeine: Chemistry, Analysis, Function and Effects - page 325

17.5.4 Caffeine and Team Sport Performance
Several investigations have examined effects of caffeine during protocols that
simulate sport such as cycling and team sports. In cyclists, caffeine increased 1 km
time-trial performance by 2 s and augmented mean and peak power compared to
placebo (Wiles et al 2006). In athletes performing 4 s sprints on a cycle ergometer,
sprint performance and mean power were enhanced by 6-8% with caffeine
(Schneiker et al 2006). In rugby players, caffeine increased parameters of intense
performance mimicking 80 min of competitive rugby, including sprint speed,
power, and passing accuracy, compared to placebo (Stuart et al 1995). These data
oppose an inability of caffeine to enhance performance of ten 20 m sprints,
interspersed with 10 s of recovery, in team-sport athletes (Paton et al 2001). The
relatively short duration of this bout compared to those used in previous studies
may explain the lack of an effect. Caffeine also does not alter agility (Lorino et al
2006), so its ability to enhance performance in sports characterized by quick
movements, turns, and-or brief sprints of short duration remains equivocal.

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17.5.5 Caffeine and Sprint Performance
Early studies failed to reveal benefits of caffeine for short-term exercise. During 15
s of all-out cycling, no change in power, work, or fatigue was revealed (Williams et
al 1988). Nevertheless, Anselme et al (1992) revealed enhanced anaerobic power
during a force-velocity test, yet no change in anaerobic capacity. However,
Collomp et al (1992) demonstrated improved 2 x 100 m swim performance in
trained swimmers with 250 mg of caffeine ingested 1 h before exercise versus
placebo. In adults, cycling time to exhaustionwasincreasedby20%(4.12to4.93
min) with caffeine (Jackman et al 1996). In men completing four Wingate tests
(Greer et al 1998), caffeine did not alter power output versus placebo, and in bouts
3 and 4, mean-peak power was lower (p,0.05) with caffeine. A detrimental effect
on performance was also revealed during intense cycling (Crowe et al 2006).
However, Woolf et al (2008) revealed significantly higher peak power, but not
mean power or fatigue index, in male athletes ingesting caffeine. Collectively, data
indicate that caffeine may be ergogenic for high-intensity exercise performed by
trained athletes, who provide more consistent performance day-day and thus
increase statistical power. For example, improved sprint cycling performance was
revealed after ingestion of 240 mg of caffeine (Paton et al 2010). An increased
sensitivity to caffeine has been revealed in human slow-twitch fibers (Mitsumoto et
al 1990), and adenosine receptors exist primarily in type I fibers (Latini and Pedata
2001), so a potential ergogenic effect of caffeine in activities depending upon fast-
twitch motor unit recruitment may be unexpected. However, further study is
needed to elucidate these explanations.

Summary Points

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This chapter reviewed effects of acute caffeine intake on exercise

performance.