Jennifer Lovejoy, Arivale Chief Science Officer, PhD
A latte before lifting? Some coffee before calisthenics? How about a Red Bull before running?
Past studies have shown that caffeine can be a performance-enhancing, or “ergogenic,” aid for many athletes–though, critically, not all athletes. A new study published last month in Medicine & Science in Sports & Exercise and covered by the New York Times looked at the genetics behind how we metabolize caffeine. It concluded that about half the population receives a performance boost from caffeine during physical activity due to their genetics–but around 10 percent of people actually see their performance decline.
Here, our Arivale experts respond to the study–which was partially funded by Coca-Cola–and its conclusions as reported in the Times and elsewhere. It seems that, as with wellness in general, genes may be only part of the story when it comes to physical activity and caffeine.
Researchers focused on two variations on a gene called CYP1A2, which they say influences how people metabolize caffeine. People who received one variant from both parents were described by the researchers as “fast caffeine metabolizers” (about 50% of the population). People who received a second variant from both parents were described as “slow caffeine metabolizers” (about 10% of the population). People who received one of each variant from their parents were called “moderate caffeine metabolizers” (about 40% of the population).
Researchers used a cheek swab to determine whether 100 male athletes were slow, moderate, or fast caffeine metabolizers then had them ride 10km on a bicycle as fast as they could after a small dose of caffeine (about one large cup of coffee), again after a higher dose (about two large cups of coffee), and finally after a placebo.
The study concluded that in general subjects performed better with caffeine in their system, especially the higher dose. Fast metabolizers rode nearly 7 percent faster after the higher dose than after the placebo. But moderate metabolizers performed about the same. And slow metabolizers rode about 14 percent slower after a higher dose of caffeine.
Researchers say it’s unclear exactly how caffeine helps or hurts athletic performance.
Arivale has found good evidence that one variant in the CYP1A2 gene, called rs762551, impacts predisposition for high blood pressure and heart attack. While the media and some genetic companies describe this CYP1A2 variant as meaning you’re a “fast metabolizer” or “slow metabolizer” of caffeine, this can be a bit misleading.
For one thing, the differences in caffeine metabolism by genotype only kick in with fairly heavy caffeine use: greater than 300mg, or three or more cups of coffee. There is no indication that a fast vs. slow metabolizer would have a different response to a single cup of coffee.
Secondly, it’s natural to assume that faster or slower metabolism of caffeine might relate to feelings of alertness, jitteriness, or trouble sleeping after consuming caffeine, but there’s no evidence the rs762551 variant in CYP1A2 has any impact on these symptoms.
So, what about athletic performance? While the study’s finding is interesting, we know that genetics are only one piece of the puzzle. And, in this case, even the genetics may be impacted by multiple factors in addition to caffeine because the CYP1A2 enzyme metabolizes many compounds, including toxins in cigarette smoke, medications such as acetaminophen (Tylenol), and even compounds found in vegetables like cabbage and broccoli. The presence of any of these factors might impact the relationship between CYP1A2 genotype and caffeine. Furthermore, the study didn’t address the effect of this gene variant on performance in women or people over 30.
When looking at athletic performance, it’s important to take a systems approach. Beyond the obvious importance of your training regimen itself, it’s important to consider your overall diet (is it optimized for carbohydrates, proteins, and fats? What about minerals and anti-oxidant vitamins?), sleep patterns, stress levels, and toxin exposures in your environment (secondhand smoke or air pollution, for example).
Most people can clearly describe whether they are “caffeine sensitive” in terms of its effect on sleep and alertness, and many athletes are similarly aware of whether caffeine helps or hurts their performance. We wouldn’t recommend loading up on caffeine before your next workout based on genetic results alone. But if you have experimented and found that caffeine benefits your athletic performance, there’s no reason not to use it.