The Science of Caffeine for Endurance Sports
Caffeine is the most commonly used ergogenic aid in the world. The majority of evidence indicates caffeine ingestion increases performance in both endurance (4, 18, 19), sustained high intensity (6, 32), and stop and go team based sports (23, 26).
It has long been thought that caffeine increases performance by promoting fat mobilization from adipose tissue. Although this does happen, enhanced free fatty acid availability does not substantially change fat or carbohydrate oxidation (usage as fuel) in working muscle (32). As a result, the ergogenic effect of caffeine is not thought to be due to alterations in substrate selection.
Most data suggest caffeine improves exercise performance by stimulating the central nervous system, and can decrease perception of pain or effort during exercise (7). Additionally, caffeine can decrease fatigue during very intense “anaerobic” exercise bouts (5). The combination of improved performance, decreased pain perception, and decreased fatigue make caffeine consumption an effective way to improve performance during sport.
Many historical studies found that caffeine dosing at 3-6 mg/kg body mass enhanced performance (10, 11), however, more recent studies showed performance benefit from more modest doses of 1-3 mg/kg body weight (13). Further, several studies have reported no dose response effect with caffeine, or if there is a dose response, there is a plateau at 3 mg/kg (3, 13, 19). Therefore, modest amounts of caffeine can result in improved performance; its incorporation into one’s nutrition regime should not follow a “more is better” philosophy. Somewhat surprisingly, the exact time an athlete consumes caffeine is not critical for improved performance. Studies have shown caffeine is ergogenic when consumed before exercise, during exercise, or after the onset of fatigue (3, 19). Therefore, athletes have a wide range of caffeine doses and ingestion times that are equally effective at improving performance.
References (Adapted from upcoming article “Caffeine and Taurine: The Perfect Marriage” -numbers not sequential).
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32. Wiles JD, Bird SR, Hopkins J, and Riley M. Effect of caffeinated coffee on running speed, respiratory factors, blood lactate and perceived exertion during 1500-m treadmill running. Br J Sports Med 26: 116-120, 1992.