Caffeine and performance in short-term high-intensity (anaerobic) exercisePrint this page
Research has shown that caffeine can have benefits in some short-term, high-intensity exercises and under certain conditions. A 2009 review looking at the effects of caffeine on anaerobic exercise performance13 considered 29 studies finding that 17 of the studies revealed significant benefits of caffeine.
It was also observed that there was significant variation between the studies. Several factors in the various studies were highlighted as potential explanations for the variation: trained vs. untrained participants, caffeine-habituated vs. non-habituated participants, slow vs. fast caffeine-metabolizers amongst the participants, different dosing regimens (fixed amount of caffeine vs. mg per kg body weight), as well as different types of tests.
The overall results of the 17 studies indicated that caffeine can have benefits in some short-term, high-intensity exercises particularly under certain conditions, such as trained athletes who had abstained from caffeine before power-based sports and team sports events following ingestion of a moderate caffeine dose.
Caffeine and sports aids
A 2009 paper looked at the effect of caffeine (3.7mg/kg body weight) in addition to a carbohydrate-electrolyte supplement in a simulated football performance. The authors found that the caffeine group better maintained, and improved, short distance sprinting and jumping performances, compared to the no-caffeine group.14 A 2011 review of the evidence has shown that the ingestion of carbohydrates with caffeine provides a significant but small improvement in endurance performance compared with carbohydrates alone. However, the magnitude of the performance benefit that caffeine provides was less when added to carbohydrate than when added to placebo.15
Short-term effects of caffeine
A 2010 paper16 reported that a caffeine dose of 6mg/kg body weight in trained women resulted in an improvement in an “all at once” test but not in a repeated test.
A further paper17 tested two different doses of caffeine (2mg/kg body weight and 5mg/kg body weight) in active participants. The ingestion of the higher caffeine dose, but not the lower, resulted in an improvement in knee extension/flexion exercise performance. This effect disappeared in the second bout meaning the benefits of caffeine were short-term only.
Caffeine and fluid balance during physical activity
Fluid balance is a particularly important topic amongst athletes, as dehydration is always a concern since it is associated with reduced performance.
A comprehensive review18 concluded that a daily intake of 300mg of caffeine (the amount found in approximately 3 regular cups of coffee) induces only a mild, short-term diuretic effect, similar to that of water, with no significant effect on overall fluid balance. The authors stated that there is no evidence that caffeine is detrimental during exercise in hot climates when fluid losses are maximal. The study further confirmed that statements suggesting the avoidance of caffeinated beverages before and during exercise are unfounded.
A 2014 meta-analysis considering the role of caffeine in fluid balance in adults during rest and exercise concluded that although caffeine produced a minor diuretic effect this was negated by exercise. The authors also suggested that concerns regarding unwanted fluid loss associated with caffeine consumption are unwarranted particularly when ingestion precedes exercise.19
A further study published in 2014 found no significant differences in measures of hydration status between those who drank coffee or those who drank water, concluding that coffee consumed in moderation by regular male coffee drinkers had similar hydrating qualities to water.4
Additionally, in 2004 the International Olympic Committee (IOC) officially removed caffeine from its list of banned substances stating that historical suggestions that caffeine’s mild, short-term diuretic effect may impair physical performance are unfounded.
Further information on fluid balance can be found here
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