Episode 27 – Caffeine and Performance

Key Topics Covered

What Is It?

  • Caffeine is a naturally occurring central nervous system stimulant.
  • It’s one of the most widely consumed stimulants.
  • Extracted from plant sources such as tea and coffee.

How Caffeine Works

  • Caffeine primarily acts on the adenosine receptor (regulates your arousal status) and inhibits it.
  • Usually, adenosine turns into GABA, this inhibits ‘arousal’ neurons –> promoting sleepiness. 
    • Caffeine blocks this process.
  • Caffeine also stimulates adrenaline production. This increases the feeling of ‘fight or flight’.
  • Caffeine is classed as Group A performance supplement.
    • Meaning that it has a strong body of evidence to support its effectiveness.
    • Legality in sport: not a banned substance by WADA 

Performance Supplementation


  • Wakefulness: 1-3mg/kg of body weight. This amount typically does not enhance performance.
  • Performance enhancing: 3-9mg/kg of body weight.
    • In practice, we opt for 3-6mg/kg of body weight.
    • Eg. a 100kg person would require 300-600mg of caffeine.
  • In saying this, the dose required is based on individual preference.
    • This can depend on the individual sport and how they feel at each dosage.
    • There is a gnome test that can dictate how quickly you metabolise caffeine. It can also assess the individuals’ risk of high-performance anxiety.


  • Reduced pain perception.
  • Increase in 1 repetition max.
  • Increase in repetitions until failure.

Sources of Caffeine supplements

  • Coffee – 25-214mg/espresso shot. The wide variation can make it difficult to dose.
  • NoDoz – 100mg or gummies. This is the most accurate supplement to dose with.
  • 150mL Energy drink – 80mg. The high amount of carbonation may cause discomfort during 1 rep max.
  • Pre-workout – 300mg/ scoop. It’s unclear how the caffeine is evenly mixed amongst the other supplements.


  • Caffeine will peak between 30-60 minutes post-consumption.
  • There’s slightly faster absorption through the blood vessels under the tongue. Therefore, caffeine gum or breath strips may have a slightly faster-acting effect.


  • Roughly 4 hours.
    • Meaning half of the caffeine will be out of your system in 4 hours.
  • Consider sleep.
    • Eg. 100kg person consuming 600mg (upper limit) at 6pm after work.
    • This means that at 10pm they’ll still have 300mg left in their system. That equates to 3 coffees before bed?!
    • This may not effect ones ability to fall asleep, but can effect quality of sleep. Which has negative effects the next day.
  • Consider a long competition day.
    • Eg. Competition day could go from 9am-4pm.
    • Therefore, caffeine and thus benefits signficantly reduce by the last competition.
    • We’ll often re-dose after 3 hours. This will depend on the individual though.

Many people have cognitive dissonance when it comes to sleep. Most people will say that caffeine does not affect their sleep, even though the evidence shows that it does.

Affects on Weight-loss

Appetite Suppressant

  • It has been reported that consuming a higher dose of caffeine will cause individuals to want to eat less.
  • However, for individuals who consistently consume high amounts of caffeine, it’s predicted that their hunger hormones will adapt. Thus not having the same effect.
  • Though, this can be useful for fat-loss phases.

Metabolism Boost

  • Total daily energy expenditure can increase by ~ 1%.
  • This is not very significant.

Help Mitigate Side-Effects

  • L-Theanine – Found naturally in tea can help offset jitters and increased heart-rate.
  • Ashwaghanda – Indian herb that can help reduce anxiety.

Relevant Links/ Resources

Studies Mentioned

Consumer Exposure to Caffeine from Retail Coffee Outlets

Relevant Resources

Alan Flanagan – Coffee and Health

Relevant Blog Posts