Caffeine has long been used as an ergogenic agent in athletics, particularly for endurance sports. It has been proved repeatedly in the literature that caffeine has a positive effect on endurance sport performance. The dosages used are moderate to high, about 5-13mg of caffeine per kg of body mass. A 170 lb person is roughly 77kg, so that dosage would range from 385mg to 1,000mg. That’s anywhere from 4 to 10 cups of coffee! Of course, there is also the possibility of negative side effects—indigestion, headaches, anxiety, agitation, restlessness, insomnia, nausea, and increased heart and respiratory rate—to name a few.
So the question becomes is there a dosage where you can get the positive effect, but without the negative side effects? A recent study examined this question, looking for a low dosage of caffeine with positive effects on performance. The findings indicate that a low dosage of caffeine—approximately 200mg—has an ergogenic effect if taken late into prolonged exercise (ie marathon). The lower dosage improved vigilance, mood, alertness, and cognitive processing. So it makes sense that the improved performance is most likely a result of the changes in brain function.
While individual sensitivity and response to caffeine varies, it is good news to read credible research that shows low dosages improved performance without so many negative side effects!
Cathlin Fitzgerald, PT, DPT, CSCS, CAFS