Caffeine and Exercise Performance - Caffeine: Chemistry, Analysis, Function and Effects - page 317

Overall, the ergogenic effects of caffeine are multifactorial and include
central and peripheral mechanisms (see Figure 17.1). Currently, adenosine
antagonism seems to be the most accepted mechanism, yet enhanced
performance is also related to altered RPE, pain, cognition, and mood,
especially in activities that are sustained or require repetitive execution of
simple tasks.

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17.3 Recommended Dosing, Timing, and Form of
Caffeine Ingestion
Caffeine is consumed as an anhydrous powder, in chewing gum, or via soft
drinks, coffee, or energy drinks. Doses ranging from 3-9 mg kg 21 body weight
improved performance in many studies (MacIntosh and Wright 1995; Graham
et al 1998; Bruce et al 2000), with a 5-6 mg kg 21 dose typically used. For a 70
kg male, this equals approximately four brewed cups of coffee. However, lower
doses are also ergogenic. In combination with a carbohydrate-electrolyte
beverage, 2.1 mg kg 21 of caffeine enhanced time-trial performance versus
placebo, although higher doses had a greater effect upon performance (Kovacs
et al 1998). Cox et al (2002) revealed that 1.5 mg kg 21 of caffeine as Coca-Cola
increased cycling performance similar to a 6 mg kg 21 dose. Yet, doses greater
than 9 mg kg 21 do not improve performance more than lower doses (3-6 mg
kg 21 ). Because of the wide range of ergogenic doses, it is important for the
individual athlete to determine a minimal ergogenic dose of caffeine to use
prior to competition.
A typical dosing regimen includes drug ingestion followed by a 60 min rest
period before exercise. This allows caffeine concentration to peak in plasma
(Graham 2001). Caffeine has a half-life of 4-6 h which may vary depending
upon the size of the ingested dose, as doses above 300 mg elicit a longer half-
life. In one study (Bell and McLellan 2002), alterations in cycling performance
were examined 1, 3, and 6 h post-caffeine or placebo ingestion. Data showed
increased performance at all time points in the non-users, yet only at 1 and 3 h
in the users. These results emphasize that exercise should be completed within
6 h of caffeine ingestion to promote ergogenic effects, with this duration
shorter in caffeine users.
Whether repeated doses of caffeine are superior than a single bolus is
equivocal. Bell and McLellan (2003) revealed no additional ergogenic effect of
a second dose of caffeine ingested 6 h after a morning dose. Repeated small
doses of caffeine (1 mg kg 21 ) ingested 20 and 40 min before a mental challenge
enhanced vigilance and alertness (Hewlett and Smith 2007), which may
support ingestion of small doses of caffeine in persons whose mood or
vigilance may wane during activity, such as soldiers, ultraendurance athletes,
hospital personnel, or firefighters.
The widespread availability and popularity of caffeine-containing energy
drinks RedBull TM

including have initiated research into the ergogenic

potential of these beverages. Improved aerobic-anaerobic performance