Ask The Sports RD: Caffeine And Performance

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Does caffeine hurt, or help when running?

For most of us, our morning isn’t complete without our cup o’ delicious caffeinated beverage.  As far as running performance goes, whether it’s coffee, tea, or caffeinated gum, caffeine is a proven central nervous system stimulant.  In modest amounts (200-300 mg) it can provide some of us with a physical and mental lift, but it is important to take into account some considerations with using it to help with sports performance.

#1) It doesn’t take the place of food: While some of us might be tempted to confuse the caffeinated kick of your morning cup of joe with the energy you’d get from toast, they are not the same. Caffeine does not replace the energy that your body gets from food.  You still need the beneficial components of foods to make energy during training or racing. Caffeine alone won’t carry you through those intervals!

#2) Some people are non-responders: While caffeine might offer stimulatory performance benefits to some, others might not notice a boost.  This is due to a genetic predisposition to either be a slow or fast metabolizer of caffeine in the liver.  Be aware: this genetic predisposition could make some more sensitive to potential insomnia and jitteriness.

#3) Higher amounts of consumption are not necessarily beneficial: The recommended amount of caffeine varies depending on weight, but about  2-6mg of caffeine per kilogram of body weight before exercise (for 140 lb person, this is equivalent to about 1-3 cups of drip coffee), one hour before endurance exercise.  Doubling down on your dosage has not been shown to produce beneficial effects and can increase the chances of experiencing gastrointestinal symptoms.

#4) Know how much you are getting: Pills, gels, and gums tend to be standardized for their caffeine content, so you know how much you are taking in. But, beware coffee and tea products can vary dramatically in caffeine content.  For instance, 1 oz of espresso has between 40-50mg of caffeine while drip coffee can contain between 80-100+mg per 8 oz. Before you reach for the caffeine pills, just like any other supplement they are not regulated by the FDA and can contain other unwanted additives that may be deleterious to performance and health.

#5) The caffeine taper might not be the best choice: For those already consuming low amounts of caffeine, one more recent study demonstrated that low caffeine consumers (<40mg/day) have a better response to caffeine ingestion before a race than those are habitual high caffeine consumers (>130mg/day).  However, that doesn’t mean you should go cold turkey on the caffeine before race day. There are only a few studies examining this recommendation, and those that do, suggest that the withdrawal symptoms experienced by habitual caffeine users could potentially impact sports performance in a negative way. So, science’s best guess is that if you’re used to a morning cup of joe, stick to your caffeine routine on race day.

Do you have a question for our RDN? Send your trail-running-nutrition quandaries to

Kylee Van Horn is a licensed Sports Registered Dietitian and competitive trail runner.

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