We know that caffeine is ergogenic, meaning that it has been shown to improve performance, particularly for endurance sports. It acts on the central nervous system to reduce perception of fatigue and reduce rate of perceived exhaustion. The current guidelines recommend 3-9mg/kg body weight of caffeine 60 minutes before exercise. However, the difference in performance enhancement changes significantly between individuals ranging from highly effective to potentially worsening performance to no effect.
You may have noticed that some people can drink coffee all day, even before bed and have no issues with sleep or anxiety or over-stimulation, whereas others, if they touch coffee after midday, they’re awake all night.
It has now been shown that depending on how much and what type of CYPA12 enzyme you have will influence how you digest caffeine. This enzyme is needed to break down caffeine (much like lactase is needed to break down lactose) and some people have much more than others and difference variations of the gene exist.
This study showed that just under 50% of subjects were fast metabolisers of caffeine and in these people, a small amount of caffeine (2mg/kg body weight) reduced their cycling time trial time by 5% and a larger amount (4mg/kg body weight) reduced it by 7%.
A second subtype of this enzyme was found in 43% of participants and for them, caffeine had no effect on their time. It did not improve it or worsen it.
A third group, making up about 8% of the athletes, found that 4mg/kg body weight caffeine worsened their cycling time by 14%!
Of course, there are other factors that influence response to caffeine including habitual caffeine use, circadian rhythm, medication and expectancy of effect. However, this study highlights the need to take an individual approach to caffeine supplementation, especially for those 8% of people in which it could be doing more harm than good!
You can probably work out whether you respond well to caffeine or not if you are a regular coffee drink or caffeine user. However, if you are not sure or want some further guidance as to how best to use caffeine to improve your sports performance, book an appointment with an Accredited Sports Dietitian to get individualised advise on how, when and how much (if any!) you should be using for optimal results.