• World’s most widely consumed pharmacologically active substance (Pesta 2013)

Caffeine in Food and Drinks

  • Coffee
  • Tea
  • Energy drinks and bars
  • Chocolate

Mechanism of Action

  • A central nervous system stimulant of the methylxanthine class (Pesta 2013)
  • Blocks adenosine (Pesta 2013) 
    • Prevents the onset of drowsiness
    • Can decrease cerebral blood flow
      • Decrease myocardial blood flow by reducing adenosine-mediated vasodilatation
  • Increased fatty acid oxidation (Pesta 2013) 
    • Increased lipolysis leads to decreased reliance on glycogen use
      • Increasing hormone sensitive lipase (HSL) activity
      • Decreases glycogen phosphorylase activity
  • Increases rates of postexercise muscle glycogen accumulation when ingested with carbohydrates after exercise-induced glycogen depletion (Pesta 2013)
  • Increases contractile force during submaximal contractions (Pesta 2013) 
    • Increases calcium release from the sarcoplasmic reticulum
    • Decrease calcium reuptake

Effect on Exercise and Rest

  • No change in cardiac output (ACSM 2013)
  • Heart rate
    • Increase in resting heart rate (ACSM 2013)
    • Increase or no change in heart rate during exercise (ACSM 2013)
  • Increase blood pressure during exercise (ACSM 2013)
  • Sprint Cycling (Paton 2010)
    • Delayed fatigue over multiple bouts
    • Elevated testosterone
    • Decreased cortisol

Ergogenic Effect

  • Increases concentration and alertness (Pesta 2013)
  • Increases cognitive function and fine motor skills (Pesta 2013)
  • Increases athletic performance (Pesta 2013) 
    • Delays the onset of muscle fatigue and central fatigue (Pesta 2013)
    • Increased anaerobic sports performance (Pesta 2013)
      • No significant performance increases in a Wingate test in untrained subjects (Pesta 2013)
      • Counters reductions in maximum dynamic strength and muscle power output on the morning (2.5–7.0%) (Pesta 2013)
        • increases muscle performance to the levels found in the afternoon.
    • Increased aerobic sports performance (Pesta 2013)
      • Increase endurance (ACSM 2013)
      • 5 mg/kg can improve sprint performance cycling and running time trial performance endurance
    • Increased cycling power output

Ergolytic and Side Effects

  • Diuretic (Pesta 2013) 
    • Potential decrease of performance during prolonged endurance events
  • Restlessness (Pesta 2013)
  • Tremors (Pesta 2013)
  • Tachycardia (Pesta 2013)

Medical Benefits

  • Possible protective effect against Parkinson's disease (Pesta 2013)
  • Possible protective effect from liver cirrhosis (Pesta 2013)
  • May decrease severity of acute mountain sickness (Pesta 2013) 
    • Must be taken a few hours prior to attaining a high altitude


  • Possibly decreases calcium absorption (Jones & Barlett 2011)
  • Increases intraocular pressure in those with glaucoma (Pesta 2013) 
    • Does not affect normal individuals

Side Effects

  • Mild drug dependence (Pesta 2013)
  • Withdrawal symptoms include sleepiness, headache, and irritability (Pesta 2013)

Banned Status

  • Since 2004, caffeine has been removed from the WADA prohibited list (Pesta 2013)
  • Although now approved, WADAs continues to monitor caffeine levels to study potential misuse in sports (Pesta 2013)


American College of Sports Medicine (2013). Guidelines for Exercise Testing and Prescription, William & Wilkins, 9, 404

Bishop D (December 2010). "Dietary supplements and team-sport performance". Sports Medicine. 40(12): 995–1017.

Jones & Barlett (2011) Nurse's Handbook of Combination Drugs, Jones & Bartlett Publishers, 10th Edition. 170-171.

Paton CD, Lowe T, Irvine A (2010) Caffeinated chewing gum increases repeated sprint performance and augments increases in testosterone in competitive cyclists. Eur J Appl Physiol. 110(6): 1243-50.

Pesta DH, Angadi SS, Burtscher M, Roberts CK (2013). "The effects of caffeine, nicotine, ethanol, and tetrahydrocannabinol on exercise performance". Nutrition & Metabolism. 10(1): 71.

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