Creatine
What is it? Overview Usage Side Effects and Warnings
Answers
askAsk

Creatine Overview

Written by FoundHealth.

Creatine is a naturally occurring substance that plays an important role in the production of energy in the body. The body converts it to phosphocreatine, a form of stored energy used by muscles.

Although the evidence for creatine is not definitive, it has the most evidence behind it among all the sports supplements. Numerous small double-blind studies suggest that it can increase athletic performance in sports that involve intense but short bursts of activity.

The theory behind its use is that supplemental creatine can build up a reserve of phosphocreatine in the muscles to help them perform on demand. Supplemental creatine may also help the body make new phosphocreatine faster when it has been used up by intense activity.

Sources

Although some creatine exists in the daily diet, it is not an essential nutrient because your body can make it from the amino acids L-arginine , glycine, and L-methionine . Provided you eat enough animal protein (the principal source of these amino acids), your body will make all the creatine you need for good health.

Meat (including chicken and fish) is the most important dietary source of creatine and its amino acid building blocks. For this reason, vegetarian athletes may potentially benefit most from creatine supplementation.

Therapeutic Dosages

For bodybuilding and exercise enhancement, a typical dosage schedule starts with a "loading dose" of 15 to 30 g daily (divided into 2 or 3 separate doses) for 3 to 4 days, followed by 2 to 5 g daily. Some authorities recommend skipping the loading dose. (By comparison, we typically get only about 1 g of creatine in the daily diet.)

Creatine's ability to enter muscle cells can be increased by combining it with glucose, fructose, or other simple carbohydrates; 1 in addition, prior use of creatine might enhance the sports benefits of carbohydrate-loading. 2 Caffeine may block the effects of creatine. 3

What Is the Scientific Evidence for Creatine?

Exercise Performance

Several small double-blind studies suggest that creatine can improve performance in exercises that involve repeated short bursts of high-intensity activity. 4 For example, a double-blind study investigated creatine and swimming performance in 18 men and 14 women. 5 Men taking the supplement had significant increases in speed when doing six bouts of 50-meter swims starting at 3-minute intervals, as compared with men taking placebo. However, their speed did not improve when swimming 10 sets of 25-yard lengths started at 1-minute intervals. It may be that the shorter rest time between laps was not enough for the swimmers' bodies to resynthesize phosphocreatine.

Interestingly, none of the women enrolled in the study showed any improvement with the creatine supplement. The authors of this study noted that women normally have more creatine in their muscle tissue than men do, so perhaps creatine supplementation (at least at this level) is not of benefit to women, as it appears to be for men. Further research is needed to fully understand this gender difference in response to creatine.

In another double-blind study, 16 physical education students exercised 10 times for 6 seconds on a stationary cycle, alternating with a 30-second rest period. 6 The results showed that individuals who took 20 g of creatine for 6 days were better able to maintain cycle speed. Similar results were seen in many other studies of repeated high-intensity exercise, although generally benefits are minimal in studies involving athletes engaged in normal sports rather than contrived laboratory tests. 7 Isometric exercise capacity (pushing against a fixed resistance) also may improve with creatine, according to some, but not all studies. 8 In addition, two double-blind, placebo-controlled studies, each lasting 28 days, provide some evidence that creatine and creatine plus HMB (beta hydroxymethyl butyrate) can increase lean muscle and bone mass. 9 The first study enrolled 52 college football players during off-season training, and the other followed 40 athletes engaged in weight training.

However, studies of endurance or nonrepeated exercise have notshown benefits. 10 Therefore, creatine probably won't help you for marathon running or single sprints. 11

High Triglycerides

A 56-day, double-blind, placebo-controlled study of 34 men and women found that creatine supplementation can reduce levels of triglycerides in the blood by about 25%. 12 Effects on other blood lipids such as total cholesterol were insignificant.

Congestive Heart Failure

Easy fatigability is one unpleasant symptom of congestive heart failure . Creatine supplementation has been tried as a treatment for this symptom, with some positive results.

A double-blind study examined 17 men with congestive heart failure who were given 20 g of creatine daily for 10 days. 13 Exercise capacity and muscle strength increased in the creatine-treated group. Similarly, muscle endurance improved in a double-blind, placebo-controlled crossover study of 20 men with chronic heart failure. 14 Treatment with 20 g of creatine for 5 days increased the amount of exercise they could complete before they reached exhaustion.

These results are promising, but further study is needed. 15

References

  1. Green AL, Hultman E, Macdonald IA, Sewell DA, Greenhaff PL. Carbohydrate ingestion augments skeletal muscle creatine accumulation during creatine supplementation in humans. Am J Physiol. 271(5 Pt 1):E821-6.
  2. Nelson AG, Arnall DA, Kokkonen J, Day R, Evans J. Muscle glycogen supercompensation is enhanced by prior creatine supplementation. Med Sci Sports Exerc. 33(7):1096-100.
  3. Williams MH, Branch JD. Creatine supplementation and exercise performance: an update. J Am Coll Nutr. 17(3):216-34.
  4. Williams MH, Branch JD. Creatine supplementation and exercise performance: an update. J Am Coll Nutr. 17(3):216-34.
  5. Leenders N, Sherman WM, Lamb DR, et al. Creatine supplementation and swimming performance. Int J Sport Nutr. 1999;9:251-262.
  6. Balsom PD, Ekblom B, Soderlund K, et al. Creatine supplementation and dynamic high-intensity intermittent exercise. Scand J Med Sci Sport. 1993;3:143-149.
  7. Mujika I, Padilla S. Creatine supplementation as an ergogenic acid for sports performance in highly trained athletes: a critical review. Int J Sports Med. 1997;18:491-496.
  8. Williams MH, Branch JD. Creatine supplementation and exercise performance: an update. J Am Coll Nutr. 17(3):216-34.
  9. Kreider RB. Dietary supplements and the promotion of muscle growth with resistance exercise. Sports Med. 27(2):97-110.
  10. Balsom PD, Harridge SDR, Soderlund K, et al. Creatine supplementation per se does not enhance endurance exercise performance. Acta Physiol Scand. 1993;149:521-523.
  11. Branch JD. Effect of creatine supplementation on body composition and performance: a meta-analysis. Int J Sport Nutr Exerc Metab. 13(2):198-226.
  12. Earnest CP, Almada AL, Mitchell TL. High-performance capillary electrophoresis-pure creatine monohydrate reduces blood lipids in men and women. Clin Sci (Colch). 1996;91:113-118.
  13. Gordon A, Hultman E, Kaijser L, Kristjansson S, Rolf CJ, Nyquist O, Sylvén C. Creatine supplementation in chronic heart failure increases skeletal muscle creatine phosphate and muscle performance. Cardiovasc Res. 30(3):413-8.
  14. Andrews R, Greenhaff P, Curtis S, Perry A, Cowley AJ. The effect of dietary creatine supplementation on skeletal muscle metabolism in congestive heart failure. Eur Heart J. 19(4):617-22.
  15. Schaufelberger M, Swedberg K. Is creatine supplementation helpful for patients with chronic heart failure? Eur Heart J. 19(4):533-4.
 
Share

0 Comments

No one has made any comments yet. Be the first!

Your Comment