What is caffeine?

Caffeine is a naturally occurring stimulant found in leaves, nuts and seeds of numerous plants. Its widespread social acceptance means that many athletes consume caffeine regularly over the day in varying amounts from coffee, tea, cola, energy drinks and, increasingly, from pre-trainer supplements or caffeinated sports products. Caffeine-containing beverages typically contain 30-120mg of caffeine but this varies widely between products and brands.  Caffeine is becoming increasingly popular in sport to help improve performance and various caffeinated supplements and sports products are now being marketed to and consumed by athletes

Caffeine and performance

The main performance benefits of caffeine appear to come from its influence on the central nervous system and resulting reduced perception of effort (exercise “feels” easier) and/or reduced perception of fatigue. Previous beliefs that caffeine increases fat use during exercise and spares glycogen are now considered unlikely to be the main pathway of performance enhancement.

Who might benefit from caffeine supplementation

Research to date suggests that a wide range of active people and sporting situations may benefit from caffeine including:

  • Team or intermittent sports
  • Endurance sports
  • High intensity, short duration sports

Recommended dosing strategy

Although early research was conducted using high doses of caffeine (6+ mg caffeine / kg body weight), more recent research indicates that lower doses can provide similar performance benefits with less negative side effects. Individual responses to caffeine vary but typically doses in the range 1-3 mg caffeine per kg body weight are sufficient to improve performance (e.g. 70-210mg in a 70kg athlete). Athletes should work with their Accredited Sports Dietitian to determine the lowest effective dose and best form of caffeine to minimise risk of side effects. The athlete also needs to work with their Sports Dietitian to determine the most beneficial timing protocol, which may include taking caffeine:

  • Before competition
  • During competition
  • Combination of before and throughout competition

Potential side effects

High levels of caffeine intake can cause declines in performance through:

  • Increased heart rate
  • Impaired fine motor control (and shakiness)
  • Anxiety and over-arousal
  • Sleep disturbances
  • Gastrointestinal upset


The incorporation of caffeine into an athlete’s nutrition plan should be considered on an individual basis. Working with an Accredited Sports Dietitian will help to ensure that the most appropriate dosing strategy and best results are achieved.

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