The Effects of Creatine Supplementation

by Scott A. Sangalang

Although creatine was discovered in 1832, until recently, little was known about its biochemical and physiological functions. Creatine is a nitrogenous amino acid derivative that is made from glycine, arginine, and methionine. About 1 gram is produced daily by glandular organs (liver, kidneys, and pancreas) and stored primarily in the muscles. Creatine is also found in meats, poultry, fish, and milk. It has been established that creatine plays an important role in quick response muscle action. During this past decade, there have been numerous studies and research on creatine because of its popularity as a dietary supplement. Although the subject of creatine supplementation is still a bit unclear, I believe it can effectively enhance an athlete's performance.

In the studies, the athletes that were put on a creatine-supplemented diet had demonstrated some extraordinary results. The subjects of creatine research significantly improved their muscle size, strength and power (Silber, 1999). Some athletes experienced a reduction of pain and soreness after a short period of maximal exercise, resulting in a faster recovery between workouts (Riley, 1998). It was also shown that the amount of exercise that is performed during a workout can be increased when using creatine (Volek, 1997).

However, creatine supplementation also exhibited some negative effects on some of the athletes and patients in the studies. The most frequent side effect in patients is muscle cramping. Many users of creatine experienced water retention, which may have been the reason for the cramping. Diarrhea is another common problem that is encountered. Weight gain, depending on the patient, can be either a drawback or a benefit. Although long term effects of creatine have not yet been determined, speculation of kidney complications has been suggested. This may be caused as a result of overworking the kidneys and an excess of toxic nitrogenous wastes.

So what does creatine do? First, we need to know that adenosine triphosphate (ATP) is a source of stored energy in the human body. ATP is used for fast, short bursts of energy although its supply is limited (Riley, 1998). When ATP is used, it loses one of its three phosphates and becomes adenosine diphosphate (ADP). An easy way to think of it is to picture ATP as a fully charged "rechargeable battery" and ADP as the drained "rechargeable battery." At this point, the creatine phosphate derivative can rephosphorylate the ADP into ATP. This is the basic reason why many athletes supplement their diet with creatine.

One of the already known roles of creatine in quick response muscle (type II muscle fibers) action has been understood for decades (Silber, 1999). This phosphocreatine-ATP "shuttle system" supplies quick energy to cells that are in need of it. When ATP is hydrolyzed to ADP + P_i , the energy is used to move the myosin along the actin, which leads to the contraction of the muscles. The reaction shown in Figure 1 is catalyzed by the enzyme phosphocreatine kinase or creatine phosphokinase (CPK). When phosphocreatine rephosphorylates ADP, it is converted back into creatine. Phosphocreatine rephosphorylates ADP into ATP mainly in the skeletal and heart muscles. This "shuttle system" also provides quick energy for the brain, nerves, retinas, and spermatozoa when they need it. Creatine's effects are best found in supporting short term, maximum intensity exercises like weight lifting and sprinting. There is no evidence of an ergogenic effect in endurance activities such as distance running and swimming ("Oral Creatine Supplementation", 1999).

In one experiment, creatine slowed the process of fatigue after short, maximum intensity performances (Silber, 1999). With creatine supplementation, more phosphocreatine is made readily available for ATP resynthesis. Without phosphocreatine, production of work from the type II muscle fibers is impaired. Muscle fatigue caused by short-term maximal exercise may be an indiction of a low ATP:ADP ratio, which may be caused by phosphocreatine depletion. The lack of phosphocreatine contributes to the exhaustion of muscles. In another experiment, subjects taking creatine performed an isokinetic cycling exercise and displayed a 25% reduction in ATP degradation (Silber, 1999).

Creatine also promotes tissue growth and protein synthesis in skeletal muscles. It was briefly shown that creatine stimulates the biosynthesis of protein myosin heavy chain (Silber, 1999). When creatine is added to a culture of growing muscle cells, noticeable protein synthesis occurs. Detection of protein synthesis was not mentioned in the reference, but the stimulation was observed within 4 hours of the creatine addition. Although the mechanism of this stimulation by creatine is not yet known, the evidence that protein myosin heavy chain is synthesized is present.

An experiment done in the United Kingdom showed some effects of creatine supplementation (Jones, 1999). Sixteen ice hockey players voluntarily participated in a double blind experiment where eight players unknowingly used creatine and the other half unknowingly took a placebo for 10 weeks. Only the researchers conducting the experiment knew which players were in the experiment and placebo groups. Each group performed three stationary bike and ice sprint tests at various times throughout the study. First, an average baseline of peak power output and mean power output on the stationary bike were determined for each group. For the ice sprints, the time measurements were made in seconds for sprints of 47m and 80m. After 10 days, measurements were made again. At 10 weeks, the final measurements were taken.

The results of the experiment somewhat confirmed creatine's advantages. In the stationary bike test, the placebo group showed no significant changes between each test period. On the other hand, the experimental group showed a significant increase in the average peak power output and average mean power output during the time period between the baseline and 10^th day. However, the experimental group did not show a significant change between the 10^th day and 10^th week. In the ice sprint test, the results were almost the same. The placebo group showed no changes, while the experimental group showed a significant change in the short sprint during the time period between the baseline and 10^th day only.

In an experiment done at Pennsylvania State University, an explanation to the reduction of soreness during creatine supplementation is given. When creatine levels are high, there is the assumption that the production of lactate will be lowered as a result of a reduced dependency on anaerobic glycolysis (Volek, 1997). With higher creatine concentrations, the phosphagen pool is used more efficiently so there would be less lactic acid accumulation in the body. However, in this particular study, there weren't any significant changes in the lactic acid concentrations between the experimental and placebo group. The elucidation to this observation was that the experimental group actually did more work than the placebo group. One exercise performed in this experiment was the bench press, where each subject completed as many repetitions as possible. The experimental group did an average of 8 more repetitions than the placebo group. The assumption of a reduced dependency on anaerobic glycolysis concurs with a study that found creatine supplementation may reduce recovery time due to the shorter amount of anaerobic glycolysis (Silverman, 1997).

The prediction of kidney malfunction due to long-term, excessive creatine supplementation is made (Silber, 1999). When creatine is metabolized, creatinine is produced as the waste product. The excessive creatine and creatinine are excreted through the kidneys to rid the body of the toxic nitrogen of the compounds. Also, the high amount of creatine and creatinine concentrations are thought to flood and overwork the kidneys. Although none of the references mentioned monitoring the kidneys, researchers believe the excess stress may burden the kidneys and cause a dysfunction.

Even though the research and studies on creatine and creatine supplementation are fairly new, there are some facts out there that users may want to know. Despite the known disadvantages, many professional athletes have turned to creatine and other supplements to help them perform at their peak level. Mark McGuire was in the news a couple of years ago for supplementing with androsteine. One of the issues of that matter was the influence he had on younger athletes. Many young athletes who look at professional sports stars as role models, may try creatine without knowing anything about it. Most amateur athletes that use creatine know of its benefits, but not its drawbacks. Even though creatine was discovered nearly 2 centuries ago, its biochemical functions are still not fully understood.

References

Anderson-Parrado, Patricia. "High-intensity activity + creatine supplementation = muscle power." Better Nutrition 59 (1997): 16-18.

"CREATINE SUPPLEMENTATION IN OLDER ADULTS." Nutrition Research Newsletter 17 (1998): 5-6.

Ekblom, Bjorn. "Effects of creatine supplementation on performance." The American Journal of Sports Medicine 24 (1996): S38-S40.

Jones, A. M., Atter, T., Georg, K. P. "Oral creatine supplementation improves multiple sprint performance in elite ice-hockey players." Journal of Sports Medicine and Physical Fitness 39 (1999): 189-96.

Juhn, Mark S., O'Kane, John W. and Vinci, Debra M. "Oral creatine supplementation in male collegiate athletes: a survey of dosing habits and side effects." Journal of the American Dietetic Association 99 (1999): 593-596.

"Oral Creatine Supplementation." Internal Medicine Alert 21 (1999): 116.

Riley, Dan and Arapoff, Jason. "The 'powerline' view on creatine." Coach and Athletic Director 68 (1998): 12-14.

Silber, M. L. "Scientific facts behind creatine monohydrate as sport nutrition supplement." The Journal of Sports Medicine and Physical Fitness 39 (1999): 179-88.

Silverman, Stephen. "What are the effects of creatine supplementation on performance?" The Journal of Physical Education, Recreation & Dance 68 (1997): 6-7.

Volek, Jeff S. et al. "Creatine supplementation enhances muscular performance during high intensity resistance exercise." Journal of the American Dietetic Association 97 (1997): 765-771.

Copyright © 2000 Scott Sangalang and Koni Stone