The NCAA News - News and Features

May 12, 1997

Sports Science Newsletter
Is it safe for athletes to use creatine?

By Dr. Priscilla Clarkson
UNIVERSITY OF MASSACHUSETTS, AMHERST

Although some athletes have used drugs to enhance performance, most recognize the danger. However, to gain a competitive edge yet not jeopardize health, some athletes have sought nutritional supplements to enhance performance. Many fad supplements have come and gone over the years, most proving to be ineffective.

Creatine has become the most popular nutritional supplement of the past decade. When this substance appeared, rumors were rampant that it could improve performance. Several British track athletes, including one gold medalist, were purported to have used creatine before the 1992 Olympic Games in Barcelona.

Since then, numerous scientific research studies have shown that creatine ingestion can improve short-term strenuous exercise performance. The reason is that creatine exists in muscle as creatine phosphate (CP), providing the high-energy phosphate necessary to restore adenosine triphosphate (ATP) levels quickly. ATP is the fuel needed to supply energy for muscular contraction. The theoretical basis for creatine as an ergogenic aid is that more CP will be stored in muscle, hence there will be a greater capacity for the immediate energy production needed for short bursts of activity. For creatine supplements to be beneficial, ingested creatine must be able to enter and be stored in muscles. Studies have shown that ingestion of 20 grams of creatine (5 grams, four times/day) resulted in marked increases of muscle creatine levels in four-to-five days.

'At last,' some may think, a nutritional supplement that has been scientifically documented to improve performance has been developed. Not only does it work, but because creatine is a naturally occurring compound in food, athletes generally consider it to be safe.

So what is the problem?

In the past couple of years, as more athletes used creatine supplements, athletic trainers noticed a relationship between creatine and muscle dysfunction. A growing number of anecdotal reports from athletic trainers around the country suggested that those athletes taking creatine were more susceptible to cramps, muscle spasms, and even pulled muscles. There may be reason to speculate that creatine could negatively affect muscle function.

In addition to enhancing performance, creatine supplementation resulted in an increase in body weight of about 1 to 3 kilograms in one week in several studies. The mechanism to explain the increase in body weight is not known. Creatine could act as an osmotic agent in skeletal muscle, increasing water retention in muscle cells. One study of rats reported that creatine ingestion (100 mg/kg body weight) for six to nine days resulted in an increase in protein in skeletal muscle, but another study of rats did not find this. Therefore, it is not known if the increase in body weight with creatine ingestion is due to an increase in muscle proteins, an increase in water retention or some combination of the two. If part of the increase in body weight were due to increased water accumulation in muscle, this might increase intramuscular pressure. If pressure inside the muscle were increased, could this contribute to muscle dysfunction in some individuals? Further research is needed to explain what causes the rapid increase in body weight after creatine ingestion and how this increase could affect muscle function.

Studies investigating the effectiveness of creatine have had subjects use the product for a short time (from four days to less than a couple of months). These studies reported minimal, if any, side effects. But what about long-term use? Are there any negative effects of long-term ingestion of creatine? The manufacturer's recommendation for the amount of this supplement to ingest is 20 grams per day for five days, then continuing on a maintenance program of five grams per day. Athletes are likely taking the initial high doses, following the maintenance program and then repeating the cycle over and over. Moreover, because creatine appears harmless, it is easy for athletes to believe that if a little is good, more is better. Anecdotal evidence suggests that athletes are taking anywhere from 2 grams per day to 10 grams per day for a maintenance program. At present, scientists know little about the effects of long-term use of megadoses of creatine.

Just because creatine is "natural," does not necessarily mean that it is safe when taken in excess. Many natural products that are ingested in excessive amounts are harmful. For example, megadoses of certain vitamins and minerals will negatively affect the absorption of other micronutrients. Creatine taken in high amounts could detrimentally affect another body process. No studies have evaluated the impact of creatine supplementation on allowing athletes to train "too hard."

Obviously, not all athletes who take creatine report problems. This implies that some individuals may be more susceptible to ill effects than others. Those individuals who have low creatine stores may show greater benefits regarding improved performance and increased muscle mass. Creatine uptake was reported to be greatest in vegetarians who were found to have the lowest creatine stores. The reason vegetarians have low creatine status is that this substance is predominantly found in red meat. The variability among individuals in response to creatine supplementation may reflect an individual's creatine status. Are those who already have adequate creatine stores at more risk of side effects when ingesting extra creatine?

It has been suggested that the reason some athletes experience muscle spasms, cramps or muscle pulls is that they are not ingesting sufficient water with the creatine supplements. We have no scientific data to say whether this is true. All in all, we need to know more about the effects of creatine supplementation.

At the February meeting of the NCAA Committee on Competitive Safeguards and Medical Aspects of Sports, many questions were raised regarding the safety of creatine. Because of the lack of knowledge concerning its side effects, the committee recommended funding to support research projects to study the effects of creatine on factors other than performance. We need to determine whether long-term use of creatine is safe, under what circumstances it might be unsafe, and whether certain individuals may be predisposed to possible negative side effects. We hope that this initiative will provide important and necessary information for the health and safety of athletes.

Dr. Priscilla Clarkson is the Associate Dean of the School of Public Health Sciences at the University of Massachusetts, Amherst, and a member of the NCAA Committee on Competitive Safeguards and Medical Aspects of Sports. She may be called at 413/545-6069.