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Figure 17.1
Proposed mechanisms for ergogenic effects of caffeine. This table
identifies all mechanisms proposed to explain performance-enhancing
effects of acute ingestion of caffeine.
Caffeine also affects CNS function by promoting serotonin release,
increasing sympathetic activity, and decreasing the activity of inhibitory
neurons through adenosine antagonism (Porkka-Heiskanen 1999).
Consequently, reduced tiredness, improved mood, and enhanced alertness
and reaction time occur with caffeine ingestion. In one study (Smith et al
2005), caffeine improved mood and performance on various tasks versus
placebo. It also enhanced vigilance and running performance during sustained
operations in soldiers (McLellan et al 2005).
Figure
17.2
Frequency of studies reporting ergogenic effects of caffeine for
endurance exercise, intense exercise, resistance training, and team
sports exercise. This table reports the frequency of studies demonstrat-
ing ergogenic effects of caffeine for various exercise modes.
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