The aim of this article is simply to inform the reader of the basic principles and foundations behind creatine and its supplementation. Its popularity is evident and likely a result of the fact that, short of macronutrients, it is one of the most researched exercise nutrition supplements to date; this compound actually has been shown in well-controlled scientific studies to be quite effective in producing desired results, unlike many, many available to the unwary athlete these days.
A Brief Description:
Creatine is an amino acid. It is normally produced in the body from arginine, glycine and methionine. Creatine plays a vital role in cellular energy production as creatine phosphate (phosphocreatine) in regenerating adenosine triphosphate (ATP) in skeletal muscle. Without ATP, muscle contraction is not possible. Oral administration of creatine increases muscle stores and may increase muscle strength and improve exercise performance. In the diet, creatine is found in meat and fish – although cooking destroys most of it.
Creatine is a naturally occurring, key component of the energy compound creatine phosphate, whose importance in muscle contraction has been apparent since the early 1900’s. Creatine synthesis occurs in kidney, where two amino acids, arginine and glycine, react to form guanidinoacetate This compound is transported to the liver, where a methyl group is irreversibly transferred from -adenosylmethionine to guanidinoacetate to form methyl guanidine-acetic acid, otherwise known as creatine.
Once synthesized, creatine is transported to the blood stream and enters the muscle tissue by an action depending on extra-cellular sodium ions and metabolic energy. In the muscle, it is phosphorylated by adenosine triphosphate (ATP), forming creatine phosphate, or phosphocreatine.
Function: The Creatine Phosphate Energy Pathway:
When a muscle adenosine triphosphate (ATP) molecules are liberated, and the resultant energy is used to fuel the movement (forming adenosine diphosphate, ADP); however, the free ATP pool in muscle tissue can suffice only for a very short period. Thus, during contractile activity, creatine phosphate transfers a phosphate group (catalyzed by magnesium ions and creatine kinase) to ADP, thereby reforming ATP, providing further energy for muscular activity.
Creatine phosphate is basically an essential storehouse for energy, which provides for muscular contraction to continue past the handful of seconds ATP allows; without it, we would be severely limited in our ability to sustain extended periods of intense physical activity.
It has been hypothesized that supplementing the diet with additional or short period and therefore performance). Basis for this lies within the assumption that additional creatine will be added to the existing pool in the muscle, which will allow for more creatine phosphate to be produced (re-synthesized) and eventually be drawn upon for energy during intense muscular action. Due to the nature of creatine’s function, it can be assumed that enhancing its muscular pool concentration will noticeably affect only those activities that rely heavily upon this anaerobic energy pathway.
A number of studies on creatine and athletic performance have clearly shown that its benefits are limited to anaerobic sports such as like weight lifting, sprinting and jumping. No direct performance benefit of creatine has been shown for endurance athletes.
In other words, endurance activity, which relies primarily on aerobic methods of energy production, will not benefit from creatine supplementation. Studies performed examining creatine’s ergogenic effects on endurance activity have shown this to be true. It can also be extrapolated in a limited fashion from existing studies that creatine supplementation is most effective in improving performance in activities with particular rest-to-work ratios.
For example, running has a rest-to-work ratio of approximately 1:1, meaning the rest phase is roughly equal to that of the work phase. Exercises such as football, basketball, rowing, or weightlifting have greater ratios phase. Thus, it can be assumed that greater creatine resynthesis will occur, allowing more room for benefit, according to this hypothesis.
While it is possible to obtain sufficient creatine in the diet, it would be necessary to consume approximately 2.4 pounds of raw beef per day to receive an average maintenance dose of creatine (5grams) (heating severely reduces creatine’s bioavailability). It is necessary to “load” your body with exogenous creatine for a period of time in order to sufficiently saturate you body’s capacity.
A relative recommendation for a typical loading phase would be to consume 285 mg/kg body weight/day (usually spaced into 5 equal servings) for 5 to 7 days. A more general recommendation would be to consume 5 grams, 4 to 5 times per day for 5 to 7 days. This has been shown to be sufficient in “maxing out” the muscles’ creatine phosphate storage ability, after which a maintenance dose generally 2 to 5 grams/day, should be undertaken to sufficiently sustain these elevated muscle creatine pools.
Intake of this compound at this rate has indeed been shown to increase muscular strength during brief, intense exercise during numerous controlled trials. It has also been noted that creatine supplementation increases muscular water retention (dubbed “cell volumizing”), likely due to fluid being transported into the cells (with creatine the weight gain experienced with initial creatine supplementation is due to this water retention). This is not standard water retention, as the fluid actually is contained within the cells, and therefore is much less likely to fluctuate as extracellular fluid does.
The most common regimen for creatine supplementation follows a two-phase cycle with a 5-10 day loading phase (20-25 g/day) followed by a variable length maintenance phase (2-5 g/day) to maintain muscle saturation.
Intracellular water accumulation promotes a fuller look to the muscles, in contrast to the puffy, bloated appearance associated with extra-cellular retention. It has been noted that only 20% of subjects who ingest creatine alone have an increase in muscle content approaching the maximal total concentration of 160 mmol of creatine/kg dry muscle. In fact, around 20 to 30% of people do not respond to creatine supplementation at all.
However, it has been shown that individuals who ingest creatine in solution combined with simple carbohydrates (370 g/day), such as with a juice or sport drink, can increase their muscle creatine accumulation by 60%, including those who do not respond to solitary creatine consumption.
This may be attributed to the enhanced insulin flux associated with simple carbohydrate ingestion. Insulin shuttles carbohydrates (and fatty acids) into muscle cells, and it can be assumed creatine is taken up much more efficiently with greater quantities of this hormone circulating.
Side effects reported anecdotally include gastrointestinal distress, nausea, dehydration and muscle cramping – but none of these effects have been documented in scientific studies. Besides, creatine is often confused with anabolic steroids. Steroids, which mimic the effects of the male sex hormone testosterone, can result in a wide variety of adverse side effects such as acne, hair loss, testicular shrinkage and psychological problems.
Although no serious side effects have been scientifically verified in subjects using relatively brief (less than 4 weeks) creatine regimens, there are anecdotal reports of muscle cramping associated with the creatine supplements. Some athletes have reported muscle cramps, muscle tears and dehydration. A cautionary note is also advised, for people with kidney disorders and for those at risk for dehydration (such as exercise in extreme heat or during cutting weight for wrestling or lightweight crew).
While clearly not everything is known about creatine or its supplementation, a plethora of support suggests it to be a safe, relatively inexpensive, and effective supplement when used appropriately. Creatine appears to be effective in specific situations – those activities which are high-intensity and require short bouts of repeated activity (e.g. weight lifting and football).
However, it can, at this point, be relatively safely predicted that this is one sport nutrition supplement that indeed enhances intense muscular action with negligible-to-non-existent side effects.