Creatine - Does It really Work?

Family physicians are familiar with being approached by exercise enthusiasts, weekend competitors and high performance athletes inquiring about ergogenic aids.

Although concerns about being named in a doping scandal flash quickly through our consciousness, in reality we realize that this is our own patient seeking our knowledgeable advice about pharmacological effects of various prescription and non-prescription substances.

Creatine is one such "performance enhancing substance" receiving current attention. It is being used by athletes making headlines, but are the benefits real, and are there significant side effects?

There are several recent studies that look at issues related to Creatine supplementation and athletic performance.Unfortunately they usually study small numbers of particpants and often only for short periods of time. Although they are often randomized controlled trials, the small numbers and short study periods may lead to false positive or negative results. Therefore they constitute Level 2 evidence.

Mike Greenwood et al¹ in Clinical Journal of Sport Medicine review reported benefits and side effects of moderate dosing with Creatine supplementation (Level 3 evidence). This article relates anecdotal reports of dehydration, cramping, muscle strains, electrolyte abnormalities as well as effects on blood pressure, lipid levels and liver kidney and muscle metabolism. It investigates previously reported enhanced anaerobic endurance, anaerobic power and improved body mass and composition.

Greenwood chose a trial dosage based on literature reviews, with a loading dose of 20-30g/day for 5-7 days and a maintenance dose of 2-5g/day during training. Subjects were male and female intercollegiate athletes.

• of the 219 athletes surveyed, 90 (41%) reported using creatine
• creatine supplementation was more prevalent among men than women.

• 92% of participants considered Creatine safe
• 89% reported gaining weight
• 81% reported a quicker recovery from intense workouts
• 47% reported increased strength

• 37% reported exceeding dosage in loading phase
• 9% reported exceeding dosage in maintenance phase

• 38% reported GI distress
• 27% reported both GI distress and muscle cramps
• 11% reported no effects with Creatine supplementation

Jakobi et al² in Experimental Physiology July 2000 looked at stimulated and voluntary contractions of elbow flexors (Level 2 evidence). They measured strength of isometric voluntary contraction, muscle activation as assessed by modified twitch interpolation technique; electrically stimulated contractile properties, electromyography (EMG), endurance time and recovery from fatigue.

• Following supplementation there was significant weight gain (perhaps due to fluid retention) in the Creatine group and none in the control group.
• Pre supplementation measures did not differ from post supplementation for maximum voluntary contraction, twitch and tetanic tensions at rest, time to peak tension, half relation time and contraction durations.
• Time to fatigue values showed a nonsignificant increase of one minute in both control and Creatine groups.

A study by Hamilton³ suggested that CrH2O may enhance upper extremity work capacity, but this enhancement may not extend to the muscles primarily responsible for overhand sports performance (Level 2 evidence).

Burke et al⁴ obtained results that indicated indicated that Creatine supplementation can significantly improve factors associated with short-duration, high-intensity activity. (Level 2 evidence) while Deutekom M et al⁵ found that short-term oral creatine supplementation resulted in increased body mass, but did not enhance muscle performance or maximal output during sprint cycling (Level 2 evidence).

Robinson et al⁶ demonstrated in their study that there appear to be no serious health effects with short term use of Creatine (Level 2 evidence), although the jury is still out on long term usage7

To summarize, self reported effects by college athletes were variable.

Reported positive effects were influenced by extreme variable training effects, dietary supplement interactions, hydration levels and humidity and other variables that could alter perception of effects. Rates of GI distress were very similar to the placebo group.

More precise testing of muscle physiology show conflicting evidence of the benefits of supplementation.

At this point in time one can accurately state that while many athletes using Creatine as a supplement think that they are seeing benefits, controlled studies show conflicting results re: increases in anaerobic endurance, anaerobic power and improved body mass or quicker recovery after intense workout.

Most of these studies were done with young males as the subjects. Unfortunately for the aging athlete, one study in older men⁸ suggests that acute oral Creatine supplementation does not increase isometric strength and only produces small increases in isokinetic performance and body mass in men over the age of 60 (Level 2 evidence).

Further research is required to prove or disprove many assumptions about Creatine supplementation. In the meantime we can advise our patients that although useage in the short term appears to be safe, the benefits may be less dramatic than expected or desired.

- John W. Mackie

Thanks to Dr. David Cudmore, Department of Family Medicine, St. Martha's Regional Hospital in Antigonish NS for reviewing the draft copy of this article.

1. Mike Greenwood, Jim Farris, Richard Kreider, Lori Greenwood, and Allyn Byars. Creatine Supplementation Patterns and Perceived Effects in Select Division In Collegiate Athletes. Clinical Journal of Sports Medicine, Volume 10, Number 3, July 2000 p191-4
    
2. Jakobi, JM., Rice CL, Curtin SV, Marsh CD. Contractile Properties, Fatigue and Recovery Are Not Influenced by Short-term Creatine Supplementation In Human Muscle. Experimental Physiology, 85(4):451-60, 2000 Jul
    
3. Hamilton KL, Meyers MC, Skelly WA, Marley RJ. Oral creatine supplementation and upper extremity anaerobic response in females. Int J Sport Nutr Exerc Metab. 2000 Sep;10(3):277-89.
    
4. Burke DG, Silver S, Holt LE, Smith Palmer T, Culligan CJ, Chilibeck PD. The effect of continuous low dose creatine supplementation on force, power, and total work. Int J Sport Nutr Exerc Metab. 2000 Sep;10(3):235-44.
    
5. Deutekom M, Beltman JG, de Ruiter CJ, de Koning JJ, de Haan A. No acute effects of short-term creatine supplementation on muscle properties and sprint performance. Eur J Appl Physiol. 2000 Jun;82(3):223-9.
    
6. Robinson TM, Sewell DA, Casey A, Steenge G, Greenhaff PL. Dietary creatine supplementation does not affect some haematological indices, or indices of muscle damage and hepatic and renal function. Br J Sports Med. 2000 Aug;34(4):284-8.
    
7. Yu PH, Deng Y. Potential cytotoxic effect of chronic administration of creatine, a nutrition supplement to augment athletic performance. Med Hypotheses. 2000 May;54(5):726-8.
    
8. Rawson ES, Clarkson PM. Acute creatine supplementation in older men. Int J Sports Med. 2000 Jan;21(1):71-5.

You can search for abstracts of the above references by following this link: PubMed