- Caffeine has several known performance-enhancing benefits for runners.
- Some experts have advised that regular coffee drinkers should go without coffee in the days before a big race, so that they can better access those benefits.
- But a review of research on the topic found no performance edge from cutting back.
Leading up to a marathon, Des Linden, winner of the 2018 Boston Marathon and known whiskey connoisseur, used to cut back on her other favorite beverage: coffee. Her reason? She wanted to better access the performance-enhancing effects of caffeine.
“It’s good to scale back so the race-morning cup of coffee and the in-race caffeine give a little more noticeable boost,” she said.
This boost, however, might be perceived, rather than real. A study recently published in Sports Medicine suggests that the practice of scaling back caffeine consumption before a race—typically called a caffeine taper—isn’t necessary to access its performance-enhancing benefits.
How caffeine works
Caffeine is arguably the best legal performance-enhancing drug an athlete can take. It works by interfering with a chemical we naturally produce called adenosine. Typically, adenosine builds up over the course of a day and binds to corresponding receptors in the brain. The more receptors that adenosine attaches to, the sleepier we feel. Caffeine blocks adenosine from binding to those receptors. This interference not only prevents you from feeling sleepy, it also signals your body to release several other hormones (dopamine, adrenaline, and noradrenaline) that make you feel even more awake.
“That’s why people perk up after a coffee: because of the inhibition of the adenosine receptors to bind, and then we get this hormonal increase in the body,” said Bryan Saunders, a researcher in the Applied Physiology & Nutrition Research Group at University of São Paulo in Brazil and first author on the Sports Medicine study.
“This all works, as well, to improve exercise performance.”
A (legal) performance-enhancing drug
Caffeine has a number of performance-enhancing effects across nearly all domains of sport. Runners will experience a decrease in perceived exertion, meaning that running at a certain intensity won’t feel as hard—and when the pace feels easier, you can maintain it for longer or potentially crank up the intensity.
Caffeine also has what’s called a glycogen-sparing effect. Glycogen is quick-acting fuel that your body stores in your liver and muscles. If you’re jogging or even running at a smooth, non-sprint pace, caffeine will prompt your body to rely more on fat than on glycogen for energy. This “spares” the glycogen, so you have it available for later in your run to keep running longer or to surge past a competitor at the end of a race.
Of course, if you’re a daily coffee drinker like Linden, you might be concerned that, over time, your habitual consumption will dull these effects. That’s the rationale behind the caffeine taper: You consume less (or no) caffeine for several days before a race to get the maximum benefits of caffeine on race day. Unfortunately, withdrawing from regular caffeine consumption comes with a number of unpleasant side effects, including fatigue, headaches, and irritability. Therefore, coffee-drinking runners everywhere are faced with the decision: Is it worth it?
Caffeine withdrawal and performance
To answer this question, Saunders and his colleagues conducted a metanalysis to see if a consensus could be drawn from existing research. They gathered studies on caffeine and exercise performance and separated them into three groups: no caffeine withdrawal, 24-48 hours withdrawal, and more than 48 hours withdrawal.
If withdrawal were necessary for caffeine to yield performance benefits, the studies with no withdrawal should show no effect of caffeine enhancing performance, those with a short withdrawal should show some effect, and those with the longest withdrawal should show the most effect. But that’s not what the researchers found.
“All three study designs showed improved performance, with no difference between them,” said Saunders. “So from that, it seems to suggest that withdrawal isn’t very important.”
Risk vs. reward
While Saunders points out that the metanalysis is simply an indication that caffeine withdrawal is unnecessary and that more specific studies are needed to confirm the finding (studies his lab is working on right now), the risk of withdrawal still might not be worth the (potential) reward.
Sports dietician and runner Lauren Antonucci, M.S. R.D.N. C.S.S.D., has seen caffeine withdrawal do more harm than good to runners’ confidence leading up to a race, especially half marathons and marathons. Therefore, she advises her clients to focus instead on other key elements of tapering that are more certain to improve their chances of race-day success.
“There’s a lot we can do before asking people to get a headache from decreasing their caffeine,” she said.
Taper strategies Antonucci recommends include hydrating properly, staying off your feet, and increasing your carbohydrate intake (carboloading) two to three days prior to the race. She prefers these strategies because they have clearer evidence of success, particularly because responses to caffeine and to caffeine withdrawal are so variable from person to person.
“It’s just like the new shoes,” she said. “Someone might get 1 percent improvement, and some people will get a 7 percent or 9 percent improvement. We don’t know until you do it.”
Using caffeine for performance
Because caffeine affects each person differently, if you’re going to use it to enhance a run, you need to experiment to see what works for you. This means testing out different quantities of caffeine, timing of consumption, and even which type of caffeinated substance you consume (coffee isn’t the only option!). Here are some guidelines to get you started:
Take the minimum dose you need. The International Society of Sports Nutrition (ISSN) recommends a dose of 3-9 mg of caffeine per kilogram of body weight for enhanced sport performance, but Antonucci says that’s too much. (Based on the ISSN recommendation, a 150-pound runner would consume 204-612 mg of caffeine. That’s up to six and a half cups of coffee.)
“If we all started drinking that much caffeine, they’d need to quadruple the number of porta-potties in the morning, because boy would we be stimulating our GI system,” said Antonucci. She recommends that most athletes max out at 2mg/kg (which is just over a cup of coffee for our 150-pound runner).
Spread out your prerace consumption. Unless you’re running the 100-meter dash, you don’t need—or want—a huge caffeine hit all at once. If you’re a coffee drinker, sip your beverage slowly throughout the morning, rather than gulping it down. Also, be careful with other caffeinated products; always read the labels to make sure you know how much caffeine you’re getting.
Try taking caffeine at different times in your run. Some marathoners like to alternate taking caffeinated and non-caffeinated gels every few miles. Others wait to consume caffeine until mile 18. Use your long runs to experiment with timing, determine what your body responds to, and decide what you like best.
Take your caffeine with carbs. There’s a reason so many athletes take their in-race caffeine in the form of a sugary gel: it works better.
“It’s a double-whammy effect,” said Antonucci. “We’re getting the glycogen sparing, the mood boosting—all of those things are happening with carbohydrate ingestion anyway, because that’s giving us energy. So carbs and caffeine work synergistically together.”
If you’re going to do a caffeine taper, substitute water. If you’re tapering off of caffeine during your 7- to 10-day taper leading up to a race, Linden recommends replacing coffee with water. This preserves the routine of sipping on something while furthering the goal of hydrating during taper. Still, if you love coffee as much as Linden, it won’t be easy.
“Even talking about a taper is hard because coffee is the thing I look forward to during the day,” Linden said.
These days, she’s less strict about reducing her coffee intake than she once was. “I just use the caffeine during the race, and as long as I’m not getting a negative effect where I’m taking less caffeine than normal, I’m pretty comfortable with that,” she said.