Caffeine and Athletic Performance: Experiment to Find Out What Works for You
To caffeinate or not to caffeinate, that is the question!
Studies have shown that drinking caffeine about an hour before racing (or training) can help boost endurance, energy and performance.
Caffeine stimulates your central nervous system, blocking the adenosine receptors (responsible for fatigue), in turn, making you feel less tired. In addition, some studies have shown that caffeine increases activation of muscle fibers, leading you to feel faster and stronger, and enhanced mood, which makes long-term repetitive efforts less daunting.
But people react differently to caffeine. For some, it’s a performance enhancer; others can be over-stimulated and see their performance decrease.
A study published in 2018 showed that more than 95 percent of the caffeine you drink is metabolized by an enzyme encoded by of a gene called CYP1A2. People with the AA version of the gene are considered “fast” metabolizers, and break down caffeine rapidly. People with the AC or CC version are “slow” or “very slow” metabolizers, meaning the caffeine they drink lingers in their bodies for much longer.
In the study, over 100 (male*) athletes received either a placebo, a low dose of caffeine (2 milligrams per kilogram of body weight), or a higher dose (4 mg/kg). If you weigh 70 kilograms, that corresponds to either 136 or 272 mg of caffeine. (A typical cup of coffee has 100 to 160 mg of caffeine.) As demonstrated in many previous studies, caffeine boosted performance. The athletes cycled three percent faster with the high dose of caffeine compared to the placebo. The improvement with the lower dose wasn’t significant.
However, genetics affected performance even more. The “fast” metabolizers in the high-dose group performed better than everyone else. But the athletes in the “CC” group, the “very slow” metabolizers, performed worse the more caffeine they ingested. Those given the higher dose of caffeine performed 13.7 percent worse!
The researchers were unable to identify reasons for the different performance levels, but usefully, they did note that around half their test subjects were in the “fast-metabolizing” group, over 40 percent were in the “slow-metabolizing” group, and eight percent were in the “very slow-metabolizing” group.
As a result, you will want to experiment with different amounts of caffeine (including zero) during training sessions to see if it’s helpful to you. And of course, repeated exposure to caffeine in foods, drinks, and supplements leads to a reduction in sensitivity through a process called habituation.
Most caffeinated sports nutrition products incorporate doses that are multiples of 50 or 100 milligrams, less than that found in a single cup of coffee. And because caffeine typically has its peak impact between 30 and 75 minutes after ingestion (a note: caffeinated chewing gum – difficult to find in Singapore! – is faster-acting), most of the research that demonstrates a positive effect on performance is based on consumption an hour before the start of activity.
In experimenting on yourself in training, consume your caffeine an hour (or half an hour) before starting your activity, and dose yourself in increasing 50 milligram increments (in separate sessions). Keep a log of doses and timings and quantifiable (i.e. times and distances) as well as qualitative (i.e. how you felt) results. It goes without saying (but I’ll say it anyway) that you should not be trying new things on race day.
A final note: caffeine will never be your body's main energy source; the calories you need in order to perform at high levels come from eating properly every day (i.e. filling your tank in the days and weeks before competition), and from nutrition supplements that contain calories (and often, electrolytes), i.e. performance nutrition that is easy to carry and easy to digest during competitions.
* The study looked at performance in male athletes only because of previous evidence that hormonal contraceptives can affect the activity of the caffeine metabolism enzyme. The male athletes were asked to abstain from caffeine consumption during the four-week period of the study, and to control for hormone levels, female athletes would have had to be tested at the same time each month across a four-month period.