Caffeine is a plant alkaloid substance that primarily works by creating actions in the central nervous system. It’s a very well-researched ergogenic aid that reduces symptoms of both physical and mental fatigue and has both stimulatory and psychological effects.
At normal doses, caffeine’s benefit is most likely due to its action as a nonspecific adenosine antagonist in the nervous system by blocking effects of adenosine and increasing transmission of excitatory neurotransmitters such as dopamine. Effects of caffeine ingestion include increased arousal, perceived energy (mental and physical), reduced sense of effort or fatigue during mental or physical tasks, improved cognition, and increased motor drive from the central nervous system to the muscles. Fat lipolysis, metabolic rate, and 24-hour energy expenditure may also be increased after caffeine ingestion. The half-life of caffeine in the body is approximately 5 to 7 hours. Moderate caffeine intake (~3 mg/kg/d) is generally recognized as safe and doses of up to ~6 mg/kg have been shown to improve physical performance. Some individuals, however, may sense jitteriness or perceive other such negative effects near 3 mg/kg.
Find the caffeine content in popular caffeinated beverages in the table below:
Beverage and Typical Caffeine Content (mg)
8 oz drip coffee: 65–180 mg depending on brew method, beans, and grind
1 oz espresso coffee: 30–50 mg
8 oz energy drink: ~80 mg
8 oz decaffeinated coffee: 2.5 mg
How Does Caffeine Benefit Endurance Performance?
Caffeine’s benefit to endurance performance largely relates to caffeine’s ability to:
decrease perception of effort during exercise
increase motivation and perceived energy
increased motor drive
Caffeine also benefits more powerful, explosive movements, likely by increasing peak force production and the rate of force production in the larger lower body muscles. It’s recommended to ingest caffeine (in coffee or another form) approximately 45 minutes prior to exercise in order to attain maximum benefit from the supplement.
