Creatine and Muscle Building
Creatine monohydrate is a popular dietary supplement for athletes interested in sports nutrition and weightlifting. There is a large body of human and animal research that suggests creatine supplementation does enhance athletic performance and the acquisition of lean muscle mass.
Creatine is synthesized in the kidneys, liver, and pancreas from the amino acids arginine, glycine, and methionine (Balsam, 1994; Greenhaff, 1997). Most creatine is stored in the muscles, with a small amount also stored in the brain. There have been numerous research studies to determine if creatine supplementation enhances the ability to gain more muscle after exercise and resistance training than can be gained through exercise and resistance weight training alone. Most of these studies have found that creatine does enhance athletic performance in both men and women. In addition, research has shown that creatine monophosphate supplements may alleviate depression in some people (Roitman et al. 2007).
In addition to supplements, creatine can be found in meat, fish and poultry, but in much smaller amounts than you would get by taking a supplement (Balsam, 1994).
Evidence That Creatine Enhances Athletic Performance
In another study, Tarnopolsky and MacLennan (2000) found that 20 grams of creatine supplementation for four days increased peak cycling power in both men and women. However, note that while most research studies find that creatine enhances athletic performance, not all studies do.
For example, Ferguson and Syrotuik (2006) examined 10 weeks of creatine monohydrate supplementation combined with a resistance training regimen on body composition and strength in women. In this study, 13 women were given creatine supplements and 13 women were given a placebo. Both groups of women participated in a resistance training program for 4 days per week. At the end of the 10 week training period, they found that both groups of women showed an increase in lean body mass, but that there was no significant difference between the two groups. They concluded that this meant that creatine supplementation does not work in women. However, keep in mind that not all research studies involving creatine demonstrate a significant improvement in strength and lean body mass for men either.
Creatine and Athletic Performance Enhancement of the Elderly
Creatine supplementation has been shown to enhance strength and muscular performance in older women (Gotshalk et al., 2007). In this study women aged 58-71 were separated into two groups. One group of women were given .3 grams per kilogram of body mass of creatine monohydrate for 7 days. The other group was given a placebo. Then the women were tested three different times over a period of three weeks for strength as measured through bench press, leg press, and hand grip. Gotshalk et al. found that women given the creatine showed an increase in strength and power. No adverse side effects were reported.
In another study, Stout et al. (2007) found that elderly men and women (aged 64-86) given creatine supplements for 14 days showed an increase in upper body grip strength and an increase in lower body muscle endurance, which was attributed to creatine's effect of delaying neuromuscular fatigue.
Is Creatine Safe?
You will often hear and read that creatine causes muscle strains, muscle cramps, heat intolerance, and other side effects. These are not supported by the research findings (Shao and Hathcock, 2006). In addition, there is some concern that creatine may adversely affect the kidneys. Most research studies have shown that creatine supplementation is safe for healthy adults as long as they don't exceed the recommended dosage (e.g., Poortmans and Francaux, 2000).
Excess creatine is converted into creatinine. Creatinine levels in urine are commonly used to test kidney function. It is normal for individuals who take creatine supplements to have elevated creatinine levels due to the increased rate of muscle creatine conversion to creatinine (Shao and Hathcock, 2006). Because of this, having an increased creatinine level does not necessarily indicate kidney pathology in persons taking creatine supplements.
There have been many studies that have shown no adverse affects from creatine supplementation and many people take creatine supplements and seem to have no problems. However, that doesn't necessarily mean that creatine has been proven safe. For example, Thorsteinsdottir et al. (2006) reported a case of a healthy 24-year-old man who developed acute renal failure and proteinuria while taking creatine and other supplements for bodybuilding purposes. The man made a full recovery after he quit taking the bodybuilding supplements. Also, because he was taking supplements in addition to creatine it is hard to know whether the creatine is responsible for his renal failure. However, as a precaution, it should be noted that it is certainly possible that the creatine may have caused, or helped to cause, his renal failure.
There is also another case of a previously healthy 20-year-old man who developed kidney disease associated with creatine use that started approximately four weeks after he started taking 5 grams of creatine monohydrate orally four times a day (Koshy et al., 1999). The man recovered after he stopped taking creatine.
Although it is possible that both of the above cases may be unusual, or may have been caused by them taking either too much creatine, or from mixing creatine with other bodybuilding supplements, the possibility exists that creatine may be hazardous for some individuals. It is up to you whether you think the potential benefits outweigh the risks.
Click here to read about my personal experience with creatine
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Thorsteinsdottir, B., Grande, J.P., and Garovic, V.D. (2006). Acute renal failure in a young weight lifter taking multiple food supplements, including creatine monohydrate. Journal Of Renal Nutrition: The Official Journal Of The Council On Renal Nutrition Of The National Kidney Foundation 16: 341-345.
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