After the Denver Broncos trounced the Green Bay Packers in Super Bowl XXXII, Broncos tight end Shannon Sharpe shared a little "secret" with ESPN and its large viewing audience. One of the team’s smartest strategies wasn’t drawn up beforehand on a chalkboard or whispered in a huddle. Instead, it came in the form of a powdery substance called creatine. This nutritional supplement has become as common in locker rooms as sweaty gym socks and Right Guard. Olympians are taking it. High school athletes are taking it. Even weekend warriors pumping iron in their basements are taking it. So what is creatine, and why do so many athletes think it’s the best thing to come along since barbells?
Creatine is an amino acid that our bodies make in the liver, pancreas, and kidneys. We also consume up to two grams of it each day in our food, especially when we eat red meat and fish. In the form of phosphocreatine, it’s an important storehouse of energy in muscle, according to Richard Kreider, Ph.D., associate professor and assistant chair of the department of human movement sciences and education at the University of Memphis in Tennessee.
When we perform short bursts of intense exercise, phosphocreatine breaks down into its two components, creatine and phosphate, and the resulting energy is used to form a high-energy molecule called adenosine triphosphate (ATP).
ATP fuels muscles when they need a quick source of energy for activities such as sprinting, but only a small amount of ATP is stored in muscle cells. In fact, the total amount of ATP in the body provides just enough energy to perform at a maximum exercise level for several seconds. This is the level that athletes attain when they deliver a serve in tennis, leap over a high jump, or throw a shot-put, not the everyday exertion of walking fast or climbing stairs at normal speed.
By regenerating ATP, phosphocreatine lets you create even more energy. As phosphocreatine is depleted, energy levels and output drop because ATP can’t be regenerated fast enough to meet the body’s demands.
That’s where creatine enters the picture. Its proponents say that by taking in extra creatine, you can make more phosphocreatine, maintain ATP levels for longer periods of time, and thereby generate more energy for sprinting, weight lifting, playing football, or any other sport that requires quick bursts of power.
A Boon for Athletes
Because creatine helps regenerate ATP more quickly, athletes need less rest and can recover faster. This helps them return to hard exercise sooner with fewer rests between sets, says Melvin Williams, Ph.D., professor emeritus in the department of exercise science, physical education, and recreation at Old Dominion University in Norfolk, Virginia, and author of The Ergogenics Edge: Pushing the Limits of Sports Performance.
To look at it another way, athletes who use this supplement are basically doing the same thing with creatine that marathoners have been doing with carbohydrates for years, namely, fueling up before exercising to top off their energy stores.
Creatine also may help delay the buildup of lactic acid that occurs in muscles during intense exercise. Lactic acid can limit the amount of intense exercise you can do because it causes a burning sensation in the muscles that makes you want to stop, especially if you haven’t exercised at that level before.
SUPPLEMENTSNAPSHOT
| Creatine May help: Enhance athletic performance and allow athletes to recover faster and increase muscle mass. Good food sources: Red meat and fish. Cautions and possible side effects: There are no long-term studies of creatine’s impact on human health; may cause cramping, muscle pulls, dehydration, and stress on the kidneys. |
Weighty Evidence
Many studies back up proponents’ claims that creatine improves the body’s ability to explode with energy. Research also shows that creatine boosts short-term muscle strength.
In one of Dr. Kreider’s studies, 25 NCAA division 1A football players were divided into two groups. One group took creatine and the other took a supplement that looked like creatine but wasn’t (a placebo). Neither the researchers nor the players knew who was receiving creatine and who was receiving the placebo. During a four-week supplementation period, the athletes participated in a standardized training program that included weight lifting, high-intensity sprinting, and football agility drills. At the end of the study, the creatine group had greater gains in weight-lifting volume, sprint performance, and weight gain.
In another study, researchers at Pennsylvania State University investigated the influence of creatine supplementation on muscle performance during repeated sets of high-intensity resistance exercise. In this study, 14 men were randomly assigned to a creatine or a placebo group. Both groups performed bench presses and jump squats before and after taking either 25 grams of creatine or a placebo.
At the end of the test period, researchers found that performance was unchanged for the men in the placebo group. The creatine group, however, had significant improvement in peak power output during jump squats and bench presses after only one week on the supplement.
Ergogenic Factors
Not all studies have shown that people gain from creatine supplementation. In a study in which Dr. Williams looked at 60-meter sprint times for highly trained athletes, he found no improvement in a creatine group when compared with a placebo group.
Despite those findings, Dr. Williams thinks that creatine is still in the running as an energy booster. He points to studies that specifically focus on ergogenic factors—that is, the ability of the supplement to boost energy production. "With any studies using ergogenic aids such as creatine, you will have variability in performance on a day-to-day basis," he says.
Also, not all types of athletic efforts can be enhanced by creatine, adds Dr. Kreider. Taking creatine for short periods of time will have little or no benefit for endurance athletes such as marathoners, for example. In fact, it may even hamper performance because creatine leads to an increase in body mass that could slow down these athletes.
Is It Safe?
Although scientists first discovered creatine more than 100 years ago, it’s only been marketed as a nutritional supplement since 1992, so there’s no way to know its long-term effects. Although proponents claim that creatine is a harmless dietary supplement, no one knows what will happen if people continue to take it for many years at the recommended dose of 5 to 25 grams daily.
"Creatine is relatively safe, and it’s a biological material that’s normally found in the body anyway. The question is, what happens if you take a lot of it over a long period of time? We don’t know that yet," says Ara DerMarderosian, Ph.D., professor of pharmacognosy and medicinal chemistry at the University of the Sciences in Philadelphia.
Dr. Kreider, however, puts a time limit on its use, noting that it’s safe for up to two years in athletes.
Some Downsides
One known potential hazard is that too much creatine can stress the kidneys, says Dr. DerMarderosian. For that reason, he recommends that anyone with kidney problems avoid the supplement altogether. Product purity is also a concern for some researchers, who claim that minor impurities could be harmful at the daily doses that athletes are taking.
Bill Bryan, M.D., clinical associate professor at the Baylor Sports Medicine Institute in Houston, says short-term creatine use leads to muscle strains, cramping, and dehydration and to weight gain that’s mostly the result of water retention. "I think it works, but there are adverse effects. Maybe not when you run tests in a laboratory or a university setting, but when you get into field conditions, there are some problems," says Dr. Bryan, who is also director of medical services for the Houston Astros baseball team.
Dr. Bryan voices another concern—that athletes will neglect good nutritional habits while taking creatine. He also doesn’t trust the influx of new products that contain not only creatine but also other unproven ingredients such as chromium.
He is not alone in his opposition to creatine. In a survey of members of the Association of Professional Team Physicians, 85 percent of respondents said they would not recommend using the supplement until more research has been completed.
Loading Up
Athletes typically take creatine in two phases, beginning with the "loading" phase. A typical loading program is a five-gram dose four times a day for a week. After that, the dose is reduced to two to five grams daily as "maintenance." This regimen can be expensive, with a one-month supply costing as much as $60.
It’s best to leave creatine to competitive athletes, says Dr. Williams. "The only reason to supplement is to enhance performance. If you’re not competitive, there’s really no reason to take it."
It’s possible, though, that in the future, creatine could be found in other places besides sweat-soaked workout rooms. According to Dr. Kreider, researchers are looking into its therapeutic value for people who experience skeletal muscle weakness due to conditions such as chronic heart failure. Researchers are also investigating whether it can help slow bone loss in the elderly. "If you can prevent the loss of lean muscle mass, perhaps you can slow down bone loss," he suggests. Finally, at least two studies have shown that creatine lowers total cholesterol. More research is expected.
