Creatine for Strength and Fitness
What is Creatine and what does it do?
Creatine is a substance found naturally in the human body, and in fact the body of any animal that has muscles. The requirement for this substance for non-athletes appears to be about 2 grams per day, of which approximately half (1 gram) comes from eating meat for non-vegetarians. The rest is produced in the body.
Creatine is formed from glycine, methionine and arginine, in a series of reactions requiring about 3 different enzymes. Its function is to increase and speed up the formation of ATP, particularly in the muscles. Detailed information about the extremely important molecule ATP can be found at the Wikipedia link here, but briefly ATP is the “energy currency” of the body and is required for anything in the body that requires energy. ATP is used up in particularly large amounts when a muscle contracts; so the supply tends to get used up fairly quickly, although it is also replenished quite quickly.
The sequence of events is as follows. Creatine is converted, using energy derived from food, into the high-energy substance creatine phosphate which is stored in the muscles. When a muscle contracts, for example when lifting a weight, ATP is depleted; the ATP is then regenerated using creatine phosphate, which is converted back into creatine in the process. Creatine phosphate is then replenished, rather more slowly, using energy from food.
Creatine phosphate can therefore be regarded as a very short-term energy store for the muscles; a storage battery, if you like. It would appear that because of this, if creatine phosphate levels can be increased beyond normal then the muscles ought to be able to keep going longer; this does appear to be the case. The simplest way to achieve higher levels of stored creatine phosphate is to consume supplemental creatine.
Creatine is therefore particularly useful for any form of sport or exercise that requires short-duration, intense effort. This obviously includes weightlifting, but also sprinting and any sport that sometimes requires a sprint – such as soccer, for example. Creatine supplementation is not particularly useful for long-duration, relatively low-intensity (at least compared to weightlifting!) exercises such as long-distance running.
Creatine also has other effects not related to its primary role. The first is that, for some unknown reason, high levels of creatine seem to increase water retention in the muscles. This pulls other nutrients with it into the muscle cells, and therefore increases the rate of growth of muscle both by increasing protein synthesis rate and decreasing breakdown of protein. The extra water also helps to slow down lactic acid accumulation, therefore increasing stamina by another route.
Creatine is also thought to increase synthesis of glycogen, the carbohydrate storage molecule in the body, but the evidence is not quite as good for this.
Creatine works even better if taken at the same time as a loading of carbohydrate, for example an energy drink. It is thought that the reason for this is that insulin doesn’t only increase the uptake rate of glucose into the tissues; it increases the uptake rate of just about everything else as well.
Creatine is stored in the body, so the convention is for a few days of loading at high intake levels followed by daily intake at considerably lower levels. Typically, the dosage for someone of average size is 20 grams per day (preferably in divided doses) for 3-4 days, and then 5 grams per day after that.
It also appears that creatine supplementation loses its effectiveness after a few months as the body gets used to it. It is probably, therefore, a good idea to take 2 weeks off every six months and then repeat the loading procedure.