What is creatine?
Creatine is a compound that is naturally synthesised in the body from certain amino acids, namely arginine, methionine and glycine. Chemically it is referred to as methylguanido-acetic acid. It is manufactured in the liver, and may also be produced in the pancreas and the kidneys. From here it is transported via the blood into the muscles, where it becomes creatine phosphate, also referred to as phosphocreatine. This change takes place by the reaction involving the enzyme creatine kinase, which helps bond creatine to phosphate, a high-energy molecule.
On average we metabolise around two grams of creatine per day, this amount can be met by the process of synthesis by the liver. Yet it is a compound that is of interest to hard training athletes due to their increased requirement for energy. Our ingested form of creatine tends to come from meat and fish, for this reason vegetarians usually have a very low level of intake via their diet. Food sources rich in creatine include beef and salmon (with around 2 grams per pound), tuna (with 1.8 grams per pound), and top of the list is herring (with 3 grams per pound). For this reason creatine was given its name, by a French scientist named Chevreul who discovered its prevalence in meat (in 1835!), from the Greek word for flesh!
How does it work?
The compound phosphocreatine is stored in muscle tissue. It has an interaction with the energy delivery system that relies on the release of a phosphate molecule from its structure. This is known as adenosine triphosphate or ATP. Carbohydrates are the chief source of fuel for ATP synthesis, if there is insufficient amounts available then lipids and proteins can also be catabolised for fuel. Adenosine Triphosphate is a large molecule that consists of a nitrogenous base (adenine), a five-carbon sugar (ribose), and three phosphate groups. The three phosphate groups are linked by two high-energy bonds. When these bonds are broken, known as hydrolysis (with the addition of water) of ATP, energy is released. A typical ATP molecule may exist for only a few seconds before it is broken down into ADP (adenosine diphosphate) and inorganic phosphate. This release of a phosphate molecule, and thus the break of one of the high-energy bonds, releases the energy that is required by the cell to perform a function. One of uses of this immediately available energy is muscle contraction. The total energy available in all of the ATP molecules of a cell can supply the energy requirements for that cell for less than a minute.
Using energy derived from the catabolism of a fuel source, such as carbohydrates, ADP can be quickly converted back to ATP as long as it can bond with another phosphate molecule. This is where phosphocreatine plays its part by donating a phosphate molecule for the recycling of ADP to ATP and thus recharging the whole sequence of events.
By increasing the available phosphocreatine pool we can maximise the ADP-ATP recycling process.
What are the practical uses for creatine in sport?
Many sports people, from serious athletes to recreational trainers, now use various forms of creatine supplementation to enhance their training and contest performance. Many of the published studies on performance enhancement have been based on anaerobic disciplines that require explosive energy over a short period of time, such as sprinting.
The role of creatine and its benefits really first became public knowledge when it was found that several British athletes, including Linford Christie, Colin Jackson and Sally Gunnell were using it to enhance their performance at the 1992 Olympics in Barcelona. It is believed that athletes from the former U.S.S.R. and Bulgaria may have been using creatine supplementation since the early 1970's.
Since the interest in creatine became world-wide numerous studies have been carried out, most of which conclude that its effects are beneficial and varied. They include:
Are there any side effects?
There seems to be little evidence of side effects, despite some unsubstantiated rumours to the contrary. A case has been put forward that due to the increased size and strength of the muscle that connective tendons could be overstressed and damaged. The actual gains in size and strength, while previously unseen from using a natural supplement, are not to be compared with those of subjects using strong anabolic steroids (where these injuries have occurred, although they are still uncommon). A side effect that is reported in a small percentage of subjects who use creatine supplementation is gastro-intestinal upset.
In many cases reducing the ingested dose and possibly taking within an hour of a meal can alleviate this.
Finally there has been a case that received worldwide coverage in the newspapers as well as specialist training magazines. It highlighted the fact that three college wrestlers in the U.S.A. died from heart attacks, and it was known that they had been supplementing with creatine. There has been no correlation found between the two factors, and it is widely accepted that many athletes in sports such as wrestling use drugs such as anabolic steroids to enhance performance. The use of diuretics is also prevalent, as it is often necessary to drop weight drastically in order to compete in a specific weight division. In Britain the use of creatine supplementation became front-page news when it was revealed that the England football team had been using it to enhance performance. No evidence of side effects has been proven, and it is rarely stated that it is in fact a naturally occurring substance within our bodies and in the food that we eat. It may be worth considering if the team had in-fact won the world cup would such a fuss have been made?
Which form to buy?
There are many forms of creatine supplementation available on the market, and many brands to choose from. The more widely recognised form to be found is creatine monohydrate, which is a creatine molecule bonded to a single water molecule. This delivers the maximum amount of pure creatine for its molecular weight. Also available, at least in the U.S.A., are creatine citrate (which is a more soluble compound) and creatine phosphate (which will deliver phosphate groups along with the creatine). It seems that creatine monohydrate is the preferred delivery medium for creatine supplementation and all of the controlled scientific studies have used this form.
Creatine monohydrate can be bought in capsules, powder or in premixed drink formulas (these have been shown to actually contain little active creatine as it degrades in liquid over a short period of time). Some formulas have creatine mixed with co-factors to enhance uptake, such as dextrose (which will cause an insulin response that shuttles the creatine into the muscles). Other formulas expand on this and add in additional amino acids, such as glutamine, taurine, and H.M.B. as well as sodium, potassium and magnesium phosphates. These formulas seem to work very well, but it is worth considering if the slight additional enhancement of uptake is worth ingesting the large amounts of simple sugars suggested? These will have negative health side effects as well as contributing towards an addition of bodyfat, not an attractive option for most athletes.
There is no doubt that additional creatine ingestion, from supplementation, works. The incidences of side effects are minimal, and usually very minor - the only one ever witnessed in research is occasional gastro-intestinal upset. What you should consider is the quality of the product that you are taking, which vary considerably in purity and toxin levels (some products have a higher level of toxic substances that are a by-product of poor manufacturing processes). Also consider the delivery system that you take to enhance creatine uptake. Some companies are now looking at combining creatine monohydrate with malto-dextrin and nutrients such as alpha-lipoic acid to enhance insulin activity and thus creatine absorption within the muscle.
Courtesy of Cain Leathem
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