What is Creatine?
Creatine is an amino acid like molecule constructed of three different amino acids Arginine, Glycine and Methionine. Our body makes a couple grams per day and the rest is obtained through our diet. It is used in muscle cells to store energy for sprinting and explosive exercise. There is about 1 g of creatine in 250 g (half a pound) of raw meat. Meat and fish are the best sources and there is no creatine in plants, therefore vegetarians have low creatine levels. 95% of creatine is stored in skeletal muscle and the other 5% in the brain and heart. Adults need to ingest about 2g/day to make up for urinary loss.
* Short term creatine supplementation can improve maximal effort muscle contractions by 5-15%, single effort sprint performance by 1-5%, and work performed during repetitive sprint performance by 5-15%.
* Creatine supplementation for 1-2 months during training has reported to promote further gains in sprint performance 5-8%, plus gains in strength 5-15% and lean body mass 1-3%.
* A British study from the university of Swansea found that creatine monohydrate improved memory and reaction times in vegetarians.
* Creatine also has shown positive effects on strength in untrained people, even in the absence of training.
Somewhere along the line, creatine got a bad rep in that it somehow damages your kidneys. The likely cause of this false accusation is failing to distinguish between creatine (the supplement) and creatinine, the diagnostic measurement for kidney problems. If serum creatinine levels are high, your kidneys could be malfunctioning. Creatinine is also the waste product of creatine, and since creatine consumption increases your creatinine levels, this creates a false positive. Over half a dozen studies have been conducted checking kidney function after creatine consumption – and no problems were found. Unless you have a pre-existing medical condition, creatine use should not damage your kidneys or liver. In one study which tracked healthy athletes over a five year period, football players who used creatine levels up to 15g/day showed no effect on markers of renal or kidney stress. Another study conducted by Oregon Health Sciences showed the kidney function of 36 healthy male and female athletes who consumed 10g/day did not adversely affect kidney function after a 12 weeks. Arkansas State University conducted two studies that found creatine use by 61 Division I athletes during training camps had no effects on muscle cramps, injury, or illness. These athletes used 15-25g/day and showed more improvement in strength gains and sprinting speed. Many people have misconceptions about the supplement because they get their information from the wrong sources. Cramping, dehydration, muscle injuries, and even death have often been associated with creatine. Some unreliable claims have suggested that athletes training in intensely hot or humid conditions might experience several muscle cramps while taking creatine. No study has reported that creatine supplementation caused cramping, dehydration, or changes in electrolyte concentrations. This study was done on highly trained athletes during intense training in a hot and humid environment. A number of reports in the media suggest that creatine supplementation can produce dehydration. There are no such studies supporting this claim. One of the most poorly researched press reports suggest that creatine may have been involved in the sudden deaths of three wrestlers. These athletes died suddenly while exercising in the heat wearing rubber suits while trying to cut weight before competition. The Centers for Disease Control and Prevention and the Food and Drug Administration decided to investigate whether creatine was involved in these deaths or not. The CDCP reported the results of the investigation and 2 of the wrestlers had not taken creatine and the other one stopped taking creatine 3 months before his death. These deaths were officially attributed to hyperthermia, heart failure, and heat exhaustion (Antonio). Several studies found that no increase was found for musculotendinous stiffness nor was there a report of muscle strain injuries (5). In a second study there were also no differences in the reported incidence of muscle injury, cramps, or any other side effects between the supplement group and placebo group. The groups showed no long-term side effects of creatine supplementation except for an increase in lean body mass (4). A third group reported no side effects at all (3). There was also one study done on renal function and again creatine showed no side effects.
Another misconception about creatine is that once one stops taking the supplement his or her gains will go away. One study showed that is not true. The gains in lean body mass were maintained while ingesting creatine (5 g per day) during a 10-week period of detraining and in the four weeks after supplementation stopped (6). Following directions that the supplement advises and drinking plenty of water can eliminate some of the possible side effects often associated with creatine.
Our skeletal muscles perform work through the breakdown of Adenosine triphosphate (ATP). ATP is broken down into Adenosine diphoshpate (ADP) and the process of turning ATP into ADP gives our muscles the energy they need to contract. ADP cannot be used to create energy for our muscles, but breaking the phosphate from ATP can. The continuation of work is based on the maintenance of ATP at a rate equal to the rate of its use, so the faster we restore ATP the faster our muscles get the energy they need to contract. The cells in our body also contain another high-energy phosphate molecule that stores energy. This molecule is called phosphocreatine or PCr (also called creatine phosphate). Unlike ATP, energy released from breakdown of PCr is not directly used to create cellular work. Instead, it helps ATP to maintain in a relatively constant supply. The release of energy from PCr is initiated by the enzyme creatine kinase, which acts on PCr to separate the P from creatine. The energy released then can be used to combine P to ADP, forming ATP. Once we have ATP we break it down into ADP and the process starts over.
During exercise ATP is maintained at relatively constant level, but the PCr is steadily declining because it is used to replenish ATP. ATP and PCr levels are low in our bodies; therefore our capacity to maintain constant ATP levels with energy from PCr is limited. Our ATP-PCr stores can only maintain energy need for a high intense activities lasting 3-15 seconds such as weightlifting and sprinting. Beyond that point our muscles must rely on other energy sources such as carbohydrates, fats, and proteins to provide for the production of ATP. They are much slower at creating ATP because they take longer to convert to a usable energy source.
About 95% of creatine is stored in skeletal muscle and about 60-70% of that is stored in the form of phosphocreatine. By increasing creatine intake the PCr levels in our bodies will increase, thus enhancing the ATP-PCr energy system by better maintaining muscle ATP levels.
Creatine allows for more phosphocreatine to be stored in the body therefore, ATP can be replenished for a longer amount of time. An event lasting 3-15 seconds could last 3-25 seconds with the aid of creatine supplementation. By extending the ATP-PCr system an athlete can get a few more reps in during each set of a workout. By doing a few more reps in each set allows the muscles to be pushed a little harder with each workout. It usually takes about 3 days of supplementing with creatine for the athlete to experience the effects of creatine. I am a pretty well trained athlete and I have experienced nothing but positive results with creatine.
One time I was training for 6 months off creatine and the week I decided to start using creatine again I went in for a chest work out on Monday and for the bench press I did 315 pounds 5 times on my first set and 4 times on my second and third sets. When I went in on Thursday to do the same work out I did 315 pounds 8 times on my first set, 7 times on my second set and for my third set I did 5 reps. I started using creatine on Monday morning and by Thursday afternoon I could already see the effects.
Antonio, Jose, Jeffrey R. Stout. Sports Supplements. Lippincott Williams and Wilkins
Groeneveld GJ, et al. Few adverse effects of long-term creatine supplementation in a placebo-controlled trial. Int J Sports Med. (2005)
Gualano B, et al. Effects of creatine supplementation on renal function: a randomized, double-blind, placebo-controlled clinical trial. Eur J Appl Physiol. (2008)
Gualano B, et al. Effect of short-term high-dose creatine supplementation on measured GFR in a young man with a single kidney. Am J Kidney Dis. (2010)
Poortmans Jr, et al. long-term oral creatine supplementation does not impair renal function in healthy athletes. Med Sci Sports Exer 1999, 31(8):110-1110.
Poortmans Jr, Francaux M. Adverse effects of creatine supplementation. Sports Med 2000;30:155-170
Wilmore, Jack H, David L. Costill. Physiology of sport and Exercise. 2004. (124-128)