NANCY CLARK: Caffeine Aids Performance

The Athlete’s Kitchen

Copyright; Nancy Clark MS RD CSSD January 2014
Caffeine: Performance Enhancement in a Mug


    For runners, caffeine is a proven performance enhancer. In their new book Caffeine for Sports Performance, sports dietitians Louise Burke and Ben Desbrow and exercise physiologist Lawrence Spriet address all-things-caffeine that a runner might want to know. Here are just a few tidbits that I gleaned from this comprehensive resource. Perhaps the information will help you add a little bit of zip to your workouts.







• The recommended performance-enhancing dose of caffeine is about 1.5 mg/lb (3 mg/kg) body weight. This can be consumed 1 hour before you run, and/or during a long run (such as a caffeinated gel or defizzed cola every hour). For example, triathletes commonly consume caffeinated gels before each segment, to distribute the caffeine throughout the event rather than have a big pre-race jolt that might make them feel shaky and unable to concentrate. Some runners delay caffeine intake until fatigue starts to appear, and then they ingest 0.5-1 mg/lb (1-2 mg/kg) body weight.




• Because the amount of caffeine in coffee and tea varies, elite runners commonly use caffeine pills or commercial products to ensure the desired intake.  A comparison of the caffeine content in 16 ounces of coffee from 20 coffee venders ranged from about 60 to 260 mg. Even when the researchers purchased the same brand of coffee (Starbucks Breakfast Blend) from the same location on six consecutive days, the caffeine content ranged from about 260 to 565 milligrams per 16 ounces.








• Caffeinated colas offer not only caffeine but also a hefty dose of sugar. Colas, taken later in a long run, can provide a much-needed source of fuel so the combination of caffeine + sugar can provide a nice boost! Hence, some runners claim defizzed Coca-Cola is their preferred sports drink despite having only 35 mg caffeine per 12-ounce can.




• Caution: Consuming caffeine might contribute to negative effects. For example, let’s say you are running in more than one competitive event in a day. If caffeine helps you go harder in the first event, will that “fry” you for the second event? Can taking another dose of caffeine counter that fatigue? With back to back events, will too much caffeine on the first day ruin your sleep, so you are unable to perform as well on the second day? More research is needed to answer those questions but for the moment, these situations provide good examples of why advice to use the smallest effective dose of caffeine is sensible.






• For even more helpful tips and tid-bits, get a copy of Caffeine for Sports Performance. You’ll actually stay awake while reading it; the book is not a snoozer!


  Boston-area sports nutritionist Nancy Clark, MS, RD counsels both casual and competitive athletes. Her private practice is in Newton, MA 617-795-1875). For information about her new Sports Nutrition Guidebook and her food guide for marathoners, cyclists, and soccer players, see For online education, see





Common Sources of Caffeine


For a 150-pound (68 kg) runner, the recommended dose of caffeine is about 200 mg one hour before exercise. That’s the amount in a large mug (16 oz) of coffee. No problem for most coffee-drinkers!


Brewed coffee

250 ml (about 8 oz; small)

80 (ranges 40-110)

Starbucks Breakfast Blend

600 ml (20 oz; venti)

415 (range 256-564)

Tea, black

250 ml (about 8 oz; small)

25 -110

Tea, green

250 ml (about 8 oz; small)



1 can (12 oz / 335 ml)


Red Bull

1 can (8 oz / 250 ml)


PowerBar caffeinated gels

1 pouch (1.25 oz / 40 g)

25 - 50

GU caffeinated gel

1 pouch (1 ox / 32 g)


Jolt Caffeine Energy Gum

1 piece



1 tablet

200 (USA), 100 (Australia)