Big Muscle vs. Fast Times

Wouldn’t it be nice if only there were a potion or powder that we could sprinkle on our breakfast cereal that would help us ride, run, or swim faster? Creatine is the hot supplement for sports requiring short, intense, repeated efforts (such as weight lifting, sprinting, basketball and hockey). It helps you muscle up, that’s for sure—but will it help you run, ride or swim faster?

What is this Stuff?
Creatine is an amino acid that is synthesized in the kidneys, liver, and pancreas, then stored in the skeletal muscle. The body uses creatine relatively slowly—the turnover rate is approximately two grams a day. Although creatine concentration is greater in fast-twitch anaerobic muscles (the kind used for sprinting and jumping), slow-twitch aerobic fibers (the kind used in endurance activity) have a greater re-synthesis capability due to their increased aerobic capacity. There appears to be no significant difference between males and females in creatine levels, and training does not affect creatine storage.

The muscles store enough creatine to fuel about ten seconds of work, and it is the first fuel available for muscle contractions. In other words, creatine fuels short-duration, intense activities, but after the first ten seconds of activity, the body increasingly receives energy from muscle glycogen followed by mobilized glucose, fat, and some protein.

Scientific Studies—and Reality
As I mentioned, there are few studies looking into creatine as an endurance supplement. Why aren’t there more? If we consider that creatine (phosphate) is a substance used to fuel the first ten seconds of exercise, the possibility of it fueling activities of greater than an hour in duration seems unlikely. As a result, such research is not often funded by the governing agencies that dole out money for what they consider “reasonable” research. Therefore, the limited body of literature addressing the effects of creatine supplementation on endurance performance isn’t surprising. The handful of existing studies are of short duration and combine anaerobic with aerobic exercise because they’re more likely to get funded. Also, they’re rarely from American universities or research institutes, still the scientific leaders in the world.

The Envelope, please
Even when the few studies that look at creatine’s effect on endurance are considered, the overwhelming consensus is that creatine does not affect performance in studies that require exercise greater than an hour in duration, take the subject to exhaustion, and measure VO2max and blood lactate concentration. One study did find that creatine supplementation decreased the fall in blood glucose during exercise, and two studies demonstrated improved interval performance following a bout of aerobic exercise with creatine ingestion. However, these were short-term studies: creatine was ingested for only five days at 20 to 25 grams per day.

Also remember that long-term ingestion of creatine causes five to eight pounds of weight gain in the muscles, and this added poundage consists primarily of water. That’s a problem if you’re an endurance athlete because you have to support your own mass while running or cycling, especially uphill, so this five- to eight-pound weight gain could be detrimental to your endurance performance.

Still, some cyclists and runners report improvement in their events after creatine use. Their argument goes something like this: Endurance performance can be improved with short intervals; creatine improves ability to perform these repeated gut-busters; therefore creatine improves endurance performance. It’s an intriguing idea, but until it’s examined, it’s little more than a syllogism.

The Bottom Line
While creatine improves short-duration, intense, repeated bouts of exercise, at this time there’s no evidence to suggest that creatine supplementation improves endurance performance. Also, the weight gain associated with creatine supplementation may hurt your performance.

Sorry, but another magic powder fails the test. You still want to get better? Train, train, train.