Two to four cups of coffee (3-6 mg/kg of caffeine) consumed before or during endurance exercise is well supported to enhance performance through direct effects on the muscle and nervous system (1, 2, 3, 4).
- Caffeine can reduce “perceived exertion” by 5.6% and improve actual exercise performance by 11.2% (5).
- Caffeine may also lessen pain perception which may also account for some of the improvement in exercise performance (6).
- Caffeine also has a stimulatory effect on lung ventilation and promotes relaxation of the bronchi which may possibly exert protection against exercise-induced asthma (7).
- Caffeine does not improve oxygen capacity, but may allow greater power outputs and longer training sessions. It does not promote strength, but instead may promote resistance to fatigue possibly by improving cell environment in active muscle (8).
- Some studies suggest mixed results when caffeine is used for strength, or short-duration, high intensity activities. Effects are greater for those individuals who do not regularly consume caffeine (9).
- Caffeine stimulates prolonged effects of dopamine, norepinephrine and epinephrine (adrenaline, noradrenaline, and also called “catecholamines”) (10, 11).
Side Effects of Caffeine Intake
Caffeine used to be banned by the International Olympic Committee, but as of 2004, it is no longer a banned substance as set by the World Anti-Doping Agency.
However, even though upper levels have been previously set by doping control agencies, performance benefits had still consistently associated with even low to moderate intakes of caffeine below the set thresholds (6).
Caffeine intake for athletic performance brings up issues of individual tolerance, sport politics, and effects on sleep, hydration and refueling (2).
Caffeine Intake Guidelines for Sports Performance
Studies suggest that only one to two cups of coffee may be needed to improve performance.
For individuals who consistently drink three or more cups a day, it is recommended that you discontinue coffee consumption two to seven days before drinking it on the day of your event as you can build a caffeine tolerance (12).
It is important to respect that responses vary by individual as some individuals have genetic markers that make them less adept at detoxifying caffeine and are extra sensitive to even low intakes of caffeine.
Additionally, you might like to add sugar and cream to your coffee which may cause confounding effects.
One study showed that caffeine alone had a better effect on performance than when the caffeine source was combined with carbohydrates (3).
General recommendations include 0-1 cup of coffee (6-8oz) per day for non-performance days and 1-2 cups (6-16oz) on performance days.
10. Jones G. Essays Biochem. 2009;44:109-23