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School of Physiotherapy

Creatine supplementation - is it effective?

Proposition for Debate - by Jenni Hall

Contents

Statement of the Topic

Creatine supplementation: Is it effective?

Introduction

Creatine supplements are in common use by athletes today of all standards. Opinions vary whether or not they have their declared effect, what side effects they produce and whether they should be on the IOC (International Olympic Committee) list of banned substances. In general, substances are only banned because of the health risk they pose to the athlete. This document will discuss the background and current knowledge of creatine, the evidence in the literature of effects (both positive and negative) of creatine supplements and the implications of this research for the athlete and clinician.

History of Creatine

Creatine (methylguanidine-acetic acid) is a naturally occurring amino acid based substance (Poortman and Francaux 1999) first identified by the French scientist Chevreul in 1832 as a constituent of meat (Balsom et al 1994). It took a number of years to confirm this. A steady flow of experiments then followed working out the role of and investigating the consumption of creatine in humans. During this time, it was discovered that not all ingested creatine was excreted. Folin and Denis, in the early twentieth century, discovered a significant increase in the creatine content of the muscles of cats after ingestion of the substance (Balsom et al 1994). On repeat of the experiment on humans there were similar results. However, on examination of more lengthy periods of creatine ingestion, it was found that after the initial early loading period where a great percentage of the ingested creatine was retained, there was a quick decline in absorption. The majority being excreted suggesting that humans have an upper limit to how much creatine can be stored. (Balsom et al 1994).

In 1928, it was documented that creatine ingestion led to an increase in body mass (Becque et al 2000), but it wasn�t until the nineteen nineties that the role of creatine as an ergogenic aid was really investigated (Balsom et al 1994, Poortmans and Francaux 1999).

Since then there has been an increasing amount of research of improving quality into this area. At the same time, there has also been an enormous rise in public use of creatine as a dietary supplement. In demonstration of this, Robinson et al (2000) reported that sales of creatine in the United States of America in 1997 totaled US$100m. Likewise a survey done in 1998 by The Independent (a British national newspaper) on 360 elite athletes showed that 44% were using the supplement regularly, which included 100% of rugby league players and 100% of weightlifters (Poortmans and Francaux 2000).

Current Knowledge of Creatine

It is now known that creatine plays a vital role in the ATP-PC system (the immediate energy system) and that 95% of the creatine in our body is stored in the skeletal muscles, the majority of the rest being found in the heart, brain and testes (Balsom et al 1994). Two thirds of this store is in the form of phosphocreatine, the rest simply as creatine (Fillmore et al 1999).

The average daily requirement of creatine is 2g/day dependent upon body size and activity levels. It is acquired from meat and other animal products (50% of our daily requirement) and from endogenous synthesis in the kidneys, liver and pancreas. (Fillmore et al 1999). Vegetarians and others who don�t ingest meat or animal products are capable of synthesizing sufficient quantities endogenously. However, it is noted in the literature that their resting levels of creatine are generally lower then non-vegetarians. (Engelhardt et al 1998).

Creatine Supplements

As a supplement, creatine is consumed as creatine monohydrate for an initial loading period of five to six days (20 ? 30g/day) followed by an unlimited period on a maintenance dose of 2-5g/day (Fillmore et al 1999, Volek et al 1999). Dosage is dependent upon body size and activity level. More accurate dosage levels have therefore been suggested as 0.3g/kg/day during the loading phase (five to six days), followed by 0.03g/kg/day during the maintenance period (Schilling et al 2001).

Reported positive effects from the supplement are:

  1. Increased muscle bulk
  2. Decreased fatigue
  3. Decreased recovery time
  4. Improved performance.

Reported side effects include:

  1. Gastrointestinal upset
  2. Tendon injury
  3. Headaches
  4. Hepatic and renal dysfunction
  5. Muscle Cramps

Unfortunately, there are many "old wives tales" about the potential harmful effects of creatine supplements. A sample of these, taken off the nutritionalsupplements.com website (accessed on 05/08/01), are as follows:

  1. "I had 2 seizures after taking creatine. Now I have huge medical bills and possible long-term damage".
  2. "I tore my bicep muscle after 3 weeks on creatine and I don't think it's just a coincidence".
  3. "Creatine put lots of muscle on my skinny body, but the kidney pain and mood swings weren't worth it".
  4. "While taking creatine, I got acne, a rash, terrible cramps and dizziness".
  5. " I'm 14 years old and I gained 16 pounds of muscle thanks to creatine".

Whether these are true or not will now be presented with a review of the current literature.

The Evidence

There are numerous short-term studies (five to six days) looking at creatine monohydrate supplements, the majority of which are well-performed double blind, randomized controlled trials. They examine the effect of creatine supplementation on high intensity, repetitive exercise such as weightlifting.

The findings of these studies are as follows:

  1. There is an increase in concentration within the muscle of both phosphocreatine and creatine (Vandenberghe et al 1999, Mckenna et al 1999). The former calculated the increase as 16%.
  2. There is an increase in body mass and fat free mass but no change in body fat levels (Mihic et al 2000).
  3. There is a decrease in fatigue during high intensity, repetitive exercise (Mujika et at 2000, Urbanski et al 2000)
  4. There is an improvement in athletic performance ranging from decreased sprint times (Mujika et al 2000) to increased isokinetic torque production (Urbanski et al 2000). This does however seem to be associated with previously trained athletes. Gilliam et al (2000) and van Leempette et al (1999) both performed a study on untrained males and found no change in peak isokinetic torque following the same loading protocol.
  5. Vandenberghe et al (1999) also noted that there was no change in the rate of phosphcreatine breakdown or resynthesis during or after high intensity intermittent muscle contractions.

There were very few studies with no effect noted. This is in contrast to the review performed by Poortmans and Francaux (2000). They found that 30% of studies showed no beneficial effect of using creatine as a dietary supplement.

In this search, studies showing no effect were directly attributable to the study design. Either there were too few subjects, too low a dose of supplement was used, or they performed the tests on previously untrained subjects.

Low subject numbers was also a failing of the medium term studies (two to eight weeks) of which there were very few available for analysis. In the three studies that were found, there were very different results. Becque et al (2000) performed a six week study on well-trained males demonstrating an increase in body mass and fat free mass, no change in percentage body fat and an increase in 1RM. In contrast, Rawson et al (1999), using subjects aged between 60 and 82 in a four week study, showed no changes in any of the above factors. The study did demonstrate a delay in onset of fatigue though. The third and final study by Leenders et al (1999) showed mixed results. Following a two week programme of creatine supplementation in male and female university swimmers, only the males showed an improvement in repeated 30 second swim times. There was no change in repeated 10 second swim times for either sex. Unfortunately only the abstract for this paper was available and therefore it is not possible to comment on other factors of the paper and study design.

In comparison with the medium term studies, there was also a lack of long-term studies (eight weeks onwards). However, in contrast, of the three found, all the results were positive. The first paper (Jones et al 1999) demonstrated a significant improvement in performance (decreased bike ergometer and ice sprint times) following 11 weeks of creatine supplementation. The second and third (Volek et al 1999, Volek et al 2000) both demonstrated an increased body mass and fat free mass. The former also demonstrated an increased performance in squat and bench press with an increase muscle fibre cross-sectional area in type I, IIA and IIAB fibres. The latter also demonstrated no change in percentage body fat and no change in blood lipid concentrations. Both studies were performed over 12 weeks with supplementation alongside a heavy resistance training programme. All three of these studies were randomized, double blind, controlled trials.

How Does It Work?

No-one fully understands the mechanisms by which creatine supplements have their effects (Schilling et al 2001) but there are three main theories:

  1. Higher concentrations of creatine phosphate in the muscles lead to a "lesser dependence on anaerobic glycolysis for the resynthesis of ATP" (Balsom et al 1994, Kamber et al 1999, Schilling et al 2001). It also leads to a delay in the onset of fatigue thus allowing a greater volume of training, in turn providing a greater stimulus for muscle hypertrophy.
  2. Improved buffering effect on ADP leading to a relatively greater supply of ATP (Balsom et al 1994).
  3. Direct or indirect stimulation of protein synthesis and therefore quicker rates of muscle hypertrophy (Balsom et al 1994) or decreased protein degradation (Young and Denome 1984 from Tarnopolsky 2000).

There is also an argument that the rapid increase in body mass and fat free mass is due to water retention within the muscles. Volek et al (1999) and Schilling et al (2001) discuss this at length and are inconclusive. They summarise that some of the effects may be due to water retention, but not all.

Side Effects

The literature, in contrast to the anecdotal evidence, consistently demonstrates that there are no side effects to creatine supplementation.

A number of studies have looked directly at this, especially the renal and hepatic dysfunctions over periods of up to 5 years (Kamber et al 1999, Poortmans and Francaux 1999, Poortmans and Francaux 2000, Robinson et al 2000, Schilling et al 2001 and Volek et al 1999) and found no negative effects. Unfortunately there are some limitations to these studies. The retrospectively performed studies have often had a large variance in the type of and length of use of creatine supplements within their subject populations and subject numbers have been small. All the studies have failed to look in detail at potential side effects that may occur in other systems, for the example the cardiovascular system. It has been shown (Poortmans and Francaux 2000) that the use of creatine monohydrate in chronic cardiac failure patients has a beneficial effect, therefore, is there a risk of negative effects in the healthy heart secondary to hypertrophy?

Other factors that need researching in future are the potential long-term toxicity effects of use of creatine supplements and the possibility of overdose, the combination of creatine supplements with other ergogenic aids such as steroids and growth hormone, the potential that reported side effects are coming from other components within the supplements (although the studies use pure creatine monohydrate, over-the-counter supplements usually contain other products as well) and the risks of using creatine supplements during major growth periods.

Implications For The Athlete

It has been shown that the use of creatine monohydrate as a dietary supplement produces an increase in body mass, fat free mass and performance whilst decreasing fatigue. It is therefore a very appealing and legal ergogenic aid for the athlete. However, it does appear to be specific to a number of factors:

  1. Age. The majority of the above studies were performed on young, healthy males. The study that wasn't (Rawson et al 1999) demonstrated no beneficial effects to body composition in males between the ages of 60 and 82. It did however decrease their fatigue levels.
  2. Gender. Over the past few years there has been increasing debate over the physiology of females. Once thought to be the same as males, it now appears that there may be differences (Tarnopolsky 2000). Within the papers studied, there were mixed effects from the utilization of creatine monohydrate as a dietary supplement. The area is therefore inconclusive at present.
  3. Training. Two studies (Gilliam et al 2000, van Leempette et al 1999) were performed on untrained males, both demonstrating no significant changes following the use of creatine monohydrate supplement.
  4. Sport. Creatine is utilized in the ATP-PC system of immediate energy provision. It therefore makes sense that it would be of most benefit to those sports highly dependent upon this system. It should be noted though, that whilst there is a prolonged use of the ATP-PC system, there is no increase in initial output (Kamber et al 1999, Volek et al 1999).

In multiple sprint sports (soccer, volleyball, ice hockey) there is a demonstrable increase in performance, possibly due to the decreased fatigue levels.

In endurance athletes exercising at 60-70% of their VO2 max for 75 minutes there is a reduction of phosphocreatine stores to 40% of their resting values (Broberg and Sahlin 1989 in Balsom et al 1994). If, as in competition, they need a burst of power (the "kick"), there is potential that the use of creatine supplements could benefit them by extending the time and therefore the distance over which they can maintain this extra pace. Engelhardt et al (1998) performed a study on triathletes using a relatively low dose of creatine (30g given over a period of 5 days) and demonstrated an increase in performance. There is a need for further studies to be performed in this area.

Overall, it has been shown that there is a positive effect on a number of factors following creatine supplementation alongside training. However, there are still a number of grey areas that need further research in order to clarify the actual effects.

Implications for the Clinician

In terms of prescription or recommendation of creatine supplements, physiotherapists have no role to play. However, it is well recognized that during treatment, athletes will often bring up topics of conversation that they may not feel comfortable discussing elsewhere. The treatment room is a confidential place and in respect to this, it is beneficial to us, as clinicians, to have a widespread knowledge on topics related to sport in order to help the athlete make an informed decision. This is particularly important with a supplement such as creatine, which is surrounded by anecdotal evidence.

Summary

In summary, from the evidence of the literature reviewed, it seems that creatine monohydrate, when used as a dietary supplement, does have beneficial effects on body composition and athletic performance. However, this does seem to be in a fairly specific target population. There is little research in this area though so this statement is not definitive and may well change in the future.

In contrast to anecdotal evidence, the literary evidence is demonstrating no side effects from creatine monohydrate use as a dietary supplement. However, as outlined above, there are some limitations to the studies currently performed and again, more research is needed to make a definitive conclusion.

Short Answer Review Questions

  1. What is the role of creatine in the body?
  2. What are the known effects of creatine monohydrate when used as a dietary supplement?
  3. Discuss how it may achieve these effects?
  4. Is there any literary evidence for side effects? What are the limitations of this evidence?
  5. Discuss the implications for an athlete considering using creatine monohydrate as a dietary supplement?

References

Balsom PD, Soderlund K and Ekblom B (1994)
Creatine in humans with special reference to creatine supplementation. Sports Medicine 18(4) 268-280.
Becque DM, Lochmann JD and Melrose DR (2000)
Effects of oral creatine supplementation on muscular strength and body composition. Medicine and Science in Sports and Exercise 32(3) 654-658.
Engelhardt M, Neumann G, Berbalk A and Reuter I (1998)
Creatine supplementation in endurance sports. Medicine and Science in Sport and Exercise 30(7) 1123-1129.
Fillmore CM, Bartolli L, Bach R and Park Y (1999)
Nutrition an dietary supplements. Physical Medicine and Rehabilitation Clinics of North America 10(3) 673-703.
Gilliam JD, Hohzorn C, Martin D and Trimble MH (2000)
Effect of oral creatine supplementation on isokinetic torque production. Medicine and Science in Sports and Exercise 32(5) 993-996. (ABSTRACT)
Jones AM, Atter T and Georg KP (1999)
Oral creatine supplementation improves multiple sprint performance in elite ice-hockey players. Journal of Sports Medicine and Physical Fitness 39(3) 189-96. (ABSTRACT)
Kamber M, Koster M, Kreis R, Walker G, Boesch C and Hoppeler H (1999)
Creatine supplementation - Part 1: performance, clinical chemistry and muscle volume. Medicine and Science in Sport and Exercise 31(12) 1763-1769.
Leenders NM, Lamb DR and Nelson TE (1999)
Creatine supplementation and swimming performance. International Journal of Sport Nutrition 9(3) 251-62. (ABSTRACT)
McKenna MJ, Morton J, Selig SE and Snow RJ (1999)
Creatine supplementation increases muscle total creatine but not maximal intermittent exercise performance. Journal of Applied Physiology 87(6) 2244-52. (ABSTRACT)
Mihic S, MacDonald JR, McKenzie S and Tarnopolsky MA (2000)
Acute creatine loading increases fat-free mass but does not affect blood pressure, plasma creatinine or CK activity in men and women. Medicine and Science in Sports and Exercise 32(2) 291-6. (ABSTRACT)
Mujika I, Padilla S, Ibanez J, Izquierdo M and Gorostiaga E (2000)
Creatine supplementation and sprint performance in soccer players. Medicine and Science in Sports and Exercise 32(2) 518-25. (ABSTRACT)
Poortmans JR and Francaux M (1999)
Long-term oral creatine supplementation does not impair renal function in healthy athletes. Medicine and Science in Sport and Exercise 31(8) 1108-1110.
Poortmans JR and Francaux M (2000)
Adverse effects of creatine supplementation: Fact of fiction? Sports Medicine 30(3) 155-170.
Rawson ES, Wehnert ML and Clarkson PM (1999)
Effects of 30 days of creatine ingestion in older men. European Journal of Applied Physiology and Occupational Physiology 80(2) 139-44. (ABSTRACT)
Robinson TM, Sewell DA, Casey A, Steenge G and Greenhaff PL (2000)
Dietary creatine supplementation does not affect some haematological indices, or indices of muscle damage and hepatic and renal function. British Journal of Sports Medicine 34: 284-288.
Schilling BK, Stone MH, Utter A, Kearney JT, Johnson M, Coglianese R, Smith L, O�Bryant HS, Fry AC, Starks M, Keith R and Stone ME (2001)
Creatine supplementation and health variables: A retrospective study. Medicine and Science in Sports and Exercise 33(2) 183-188.
Tarnopolsky MA (2000)
Gender differences in metabolism; Nutrition and supplements. Journal of Science and Medicine in Sport 3(3) 287-298.
Urbanski RL, Vincent WJ and Yaspelkis BB (1999)
Creatine supplementation differentially affects maximal isometric strength and time to fatigue in large and small muscle groups. International Journal of Sports Nutrition 9(2) 136-45. (ABSTRACT)
Van Leemputte M, Vandenberghe K and Hespel P (1999)
Shortening of muscle relaxation time after creatine loading. Journal of Applied Physiology 86(3) 840-4. (ABSTRACT)
Vandenberghe K, Van Hecke P and Van Leemputte M (1999)
Phosphocreatine resynthesis is not affected by creatine loading. Medicine and Science in Sports and Exercise 31(2) 236-42. (ABSTRACT)
Volek JS, Duncan ND, Mazzetti SA, Staron RS, Putukian M, Gomez AL, Pearson DR, Fink WJ and Kraemer WJ (1999)
Performance and muscle fiber adaptations to creatine supplementation and heavy resistance training. Medicine and Science in Sports and Exercise 31(8) 1147-1156.
Volek JS, Duncan ND, Mazzetti SA, Putukian M, Gomez AL and Kraemer WJ (2000)
No effect of heavy resistance training and creatine supplementation on blood lipids. International Journal of Sport Nutrition and Exercise Metabolism 10(2) 144-56. (ABSTRACT)

Exercise Physiology Educational Resources 2001