Creatine and its functions in the organism
What is creatine and what is its role and purpose in our organism? What is the need and its metabolism? We should be capable to answer these questions before we decide to implement a creatine supplement into our diet.
8 min
It is important to realize what we expect from creatine supplementation, because a lot of potential users have only vague idea how creatine works. A lot of people might think that creatine is some sort of anabolic steroid and that they can expect direct muscle growth. And of course they get disappointed. This is not to state that creatine is not one of the most effective and tested sports supplements, but to maximize its advantages, we need to understand it. So, let’s go for it.
First discovery of creatine
Creatine was discovered already in 1832 in meat and that’s where its name originates – from the Greek “kreas” or “meat” (obvious similarity to later-discovered carnitine in meat, too). This is fully rightful since 95% of creatine occurs in muscle tissue (in meat), and only 5% in other organs – heart, brain, and testicles. Total amount of creatine ranges from 100 to 140 grams and its daily turnover is approx. 2 grams.
What actually is creatine and how is it produced?
It is a natural body amino acid that is produced by the organism during synthesis of three amino acids – glycine, arginine, and methionine. This happens in the livers, pancreas, and mainly in kidneys. There is only a limited ability of the body to proceed with this synthesis and it happens only to supply the amount that was not supplied by regular nutrition – and nutrition is the main source of creatine.
Where can we find creatine and in which amounts?
The fact that creatine predominantly occurs in meat is not good news to vegetarians and all others who avoid meat in their diet. Meat is the main source of creatine. Another source of creatine is fish – for example if we consumed herrings in a larger amount, we get 6,5 to 10 grams of creatine per 1 kg. We can find a bit less of creatine in salmon (4,5 g per 1 kg), tuna (4 g per 1 kg), and cod (3 g per 1 kg). Meat, pork or beef, contains between 4,5 to 5 g of creatine per 1 kg. Very popular poultry meat (not only in the bodybuilder industry) is also a rich creatine source with its 4,5 to 5,6 grams per 1 kg. Dairy products lovers – we must disappoint you. Milk contains only 0,1 g per 1 litre of milk – so that is not your choice on the way to high creatine intake.
All the above mentioned is the first strong argument to use creatine in the form of supplement – who would like to consume 1 kg of beef, pork, or poultry a day? Not to mention herrings… Let’s compare the price of meat and creatine – and the decision is crystal clear.
Role of creatine in the organism
We have already said what creatine is, where it is produced, and how much of it we can find in a human body and in its natural sources, but what is its role?
We can already have a clue by knowing that almost 100% of creatine is stored in muscle tissue – directly in the muscle cell. As sportsmen we are focused on one very simple statement: creatine is absolutely essential and immediate energy source for muscle activity. The duration and quality of muscle work is directly dependent on the creatine amount. We can consider these two axioms (unquestionable statements) that are the base of why we should use creatine supplements!
Energy sources of muscle work create some kind of cascade or sequence, where the energy source of the muscle operations follow one another, but also mutually overlap and complete each other. Let’s take a closer look at what is the meaning of creatine among other sources of muscle work.
ATP, ADP, and details of how creatine works
Creatine is stored in a muscle cell in the form of CP (creatine phosphate). Together with ATP (adenosine triphosphate) they create a compound of so called macroergic phosphates that are a direct and immediate source of energy for muscle functions. In the moment where we commence any muscle operation, ATP immediately starts to be used – it starts to split into ADP (adenosine diphosphate) and a large amount of energy is released. But do not imagine that this source would cover even a short sprint to the bus stop – the amount covers only a few seconds – and that would be the end for us if another source would enter the game – the “backup” energy source, creatine phosphate. It releases its phosphate bond in favour of ADP, ATP is restored and splits again… and this keeps repeating. It is a continual cycle, but at its best, it lasts to up to several tens of seconds. If the muscle work lasts longer, other energy sources must be used, such as muscle glycogen, and later fats, or more specifically fatty acids. But these following phases do not interest us now, when we focus on creatine.
We are interested in those tens of seconds of high intense muscle work, when the process is dependant on the amount of creatine phosphate in the muscle cell – and this is something that can be affected by using creatine sports supplements. Sprints of any kind, high intensity during ice hockey or football, or series in bodybuilding that last 40 to maximum 60 seconds – this is the key space where creatine can play its part. We can intensify or training, do two to three more reps in a series, reduce resting times… this all can be implemented thanks to creatine supplements. We shouldn’t expect a strong effect of creatine for one-time extreme physical performances – such as weight-lifting where creatine supplementation does not get a change to help. The same is valid for the other extreme – long-term endurance performances.