5 Truths about Running and Caffeine

As a registered sports dietician, I spend a lot of time advising athletes. Our introductory meetings always include a review of performance goals, current nutritional status, and recent food intake. Invariably, the conversation turns into some sort of confession – but not the kind you’d expect.

Rarely do athletes admit to excessive intake of chips or doughnuts. No, the confessions are more along the lines of, “I don’t eat many vegetables,” or “I need to cut out coffee.”

The first confession I can work with – there are plenty of ways to add veggies to the diet. But the second? I just don’t understand why an endurance athlete feels shame for loving java. Not only can coffee be linked to health benefits, but it’s also a potent source of caffeine. And caffeine is one of the most popular ergogenic aids in the world for good reason – it works.

How does caffeine affect exercise?
It can be more than just a morning pick-me-up. Caffeine has a number of physiologic effects that can help improve athletic performance. It is rapidly absorbed in the gastrointestinal tract and is a mild stimulant that affects multiple organ systems.

Can you get too much of a good thing?
While there is no consistent evidence for adverse effects on a healthy cardiovascular system, some athletes – like those with preexisting heart conditions, pregnant women, or those on certain medications – should limit their intake. And just like you discovered in college while pulling an all-nighter, if you consume too much caffeine, sleeplessness and jitters are likely to occur (especially in people not used to caffeine). As for leaching the calcium out of your bones? No convincing research links caffeine to osteoporosis.

How might caffeine help high-intensity workouts?
Caffeine is known to increase circulation of free fatty acids, which means that it’s glycogen sparing. And studies show that supplementation of caffeine (between 3-6mg/kg) is effective in reducing perceived exertion (meaning that five-minute kilometre feels like a six-minute kilometre). In fact, studies have found that swimmers are faster after 6mg/kg body weight administered in a fruit juice drink two- to five hours before the swim and reported lower perceived exertion. And cyclists’ time to exhaustion was nearly 15 minutes longer while caffeinated with 330mg caffeine one hour before exercise.

How much do I need?
Three to 6mg/kg body weight is recommended for endurance exercise (and more is not necessarily better – benefits do not rise with higher dosages). More pronounced effects might be perceived if you abstain from caffeine for several days before the exercise, but if you simply can’t live without your morning cuppa, the research isn’t compelling enough to force you to forego it.

Where can I find it?
According to Center for Science in the Public Interest, Starbucks espresso (75mg/shot), black tea (30-80mg/250mL), green tea (35-60mg/250mL).

Many runners rely on caffeine-laced gels, blocks, and beans for a mid-run pick me up. Because there are many levels of caffeine in these products, always be careful to check the label of your favorite flavour to see how much it might contain. In general, if a product contains caffeine, it likely offers somewhere between 25-100mg per serving. Athletes who don’t often use caffeine but want to try out a mid-run fuel with some kick would do well to start with a conservative 25mg dose and see how they respond.

Remember, while you may find that caffeinated fuel is just the kick you need to make it through a long run or race, the effect of this ergogenic aid can be cumulative. So if you consume double-espresso gels every hour of a long run, you should plan on staying up past your bedtime or until the post-run jitters wear off.


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