a pretty basic summary: (http://www.brianmac.demon.co.uk/creatine.htm
Phosphocreatine (the phosphorylated form of Creatine) provides the means of regenerating small quantities of ATP extremely rapidly, so boosting short duration activities. Muscles are much less prone to fatigue and the capacity to undertake strenuous exercise is increased. Activities such as repetition weight training, short sprints, repeated bounding and jumping are all enhanced and therefore the quality of training increases which feeds into higher competitive performances. Studies made with middle distance athletes also seem to point to improvement.
Creatine is both made by the body (from amino acids arginine, glycine and methionine) and gained from the diet. It occurs naturally in meats and fish. An athlete who is a big meat eater may have in his muscle five grams of creatine per kilogram of muscle, which is near the upper limit. This same athlete must take in approximately 2.5g of creatine per day to replace the natural degradation of creatine that takes place each day.
If you were to survey athletes you would find that there would be a wide variation in creatine content with some athletes having as little as three grams per kilogram of muscle, especially vegetarians and those people who are less active in sport. Those with low creatine content may be at a disadvantage since creatine has been described as the oil of the muscle engine which makes the muscle work more efficiently. Since very few athletes are at the top end of the scale (4.5- 5g/kg) supplementation will help to increase the creatine content in the muscles.
Much of the early work was based on supplementing creatine in five gram doses, four times a day for five days, then using two to three grams per day to maintain the enhanced levels. Studies based upon this level of supplementation observed rises in muscle creatine that resulted in an increased power output of about 5 - 7 per cent, presumably due to enhanced phosphocreatine levels. Manufacturers will claim significant increases in performances but in my experience the increases are varied, from no effect at all to very significant increases.
Those at the bottom end of natural creatine muscle content will benefit the most whereas those at the upper end of the scale will have no benefit since it appears impossible to increase very high levels of creatine in the muscle. Perhaps those athletes who eat very low amounts (or none) of fish and meat will be the ones who benefit the most. Vegetarians who supplement with creatine may experience significant improvements. Athletes in the explosive events (sprints, jumps, throws) are likely to experience the most improvement but in the middle distance events in which phosphocreatine plays a small but important role the benefit of creatine supplementation has yet to be finally established. Latest research points to the body being unable to absorb large amounts of creatine into the muscle and it appears that five gram intakes will largely find their way into the urine rather than into the muscle.
It is now recommended that two to three gram intakes four times a day for 10 days will lead to less being eliminated in the urine, or a regime of three gram twice a day for 20 days may he equally beneficial. After such 'loading' intakes a maintenance dose of perhaps only two gram per day is needed. For best effects creatine should not be taken all year round and periods of no supplementation should be included in the annual cycle. To bring about a rapid elevation in the muscle creatine content, supplementation is best taken either before or after training itself. At other times of the day creatine should be co-ingested with a source of carbohydrate which is effective in elevating blood insulin levels, e.g. a Mars bar. There appears to be no long term effect in taking creatine supplements although it must be pointed out that the longest study, thus far is for only one-and-a-half' years.
Since creatine is a natural component of the human diet athletes would therefore encounter creatine in the normal diet on a daily basis throughout their lives and there should be no harmful side effects. There appear to be some problems experienced by a minority of sprinters when loading with creatine in the form of muscle cramps and this may be related to the amount of the creatine supplemented. Athletes must experiment with the amount of creatine they need - more is not necessarily better and 'less may be best' in certain individuals.
Creatine, introduced and established in the nineties, will be with us into the next century, but further studies are needed to prove just how beneficial it is to athletes and in which events. The current advertising by commercial producers of creatine almost certainly exaggerates the benefits of creatine but it appears that some, if not all, adult athletes will benefit from creatine supplementation.
Creatine boosts muscle power
Investigations at the University of Nottingham show that five days of creatine supplementation can boost muscle power and performance during intense strength training ("Creatine Ingestion and Exercise Performance", International Journal of Sports Medicine, vol. 14, p. 297, 1993). In the Nottingham study, 12 athletes carried out five bouts of 30 maximal contractions of the quadriceps muscles before and after five days of placebo or creatine ingestion. The creatine was consumed in five-gram doses, four times per day (20 grams total per day). After the five days, the placebo-group athletes achieved no gains in muscle power, but creatine ingesters boosted muscle strength considerably during all five bouts of exercise.
Roger Harris, Professor of Sports Science at the University College of Chichester indicates that the traditional dosage of 20 gram per day, in 5 gram doses, may not be the most cost effective method. This amount of creatine (5 grams) cannot be picked up all at once by the muscles and as much as two-thirds can end up in the kidneys to be expelled in your urine. Meat products are natural dietary sources of creatine and a pound of raw beef contains about 1.8 grams. When we eat meat the creatine is absorbed gradually into the muscles with very little being lost in the urine. Perhaps the approach is to take small amounts of creatine and to mix it with other food. Research has shown that taking 3 grams of creatine a day over a 30 day period produces about as much creatine storage as a 20 gram/day strategy. It is also considered that the 3 gram/day strategy will reduce the amount of water retention and weight gain. To reduce cost, minimise side effects and yet obtain the benefits from creatine then perhaps a possible strategy to enhance creatine levels is to:
purchase a basic inexpensive creatine powder
take a daily dose of 3 grams or so a day over a 30 day period
take half a gram to a gram at one time sprinkled on your food
A maintenance dose of creatine would probably be about 3 to 4 grams per day and a dose of 9 grams per day could be appropriate for the seven days leading up to a major competition.
Since this page has been available on my web site I have received feedback from a number of athletes who have experienced negative side effects whilst taking creatine. They have experienced:
a significant increase in muscle swelling due to the storage of more water around the muscles - this has the potential to increase the chances of injury, especially between muscle and tendon connections
leg tendons (calf) have tightened up considerably and with reduced circulation, restricted by the swelling in the calf muscle, has led to numb feet
Cramp possibly due to water retention
Dizziness if excessive quantities taken
If you experience these side effects then possible solutions may be:
to use a very small quantity (3 grams) maybe every other day
not to use creatine