Creatine (from the Greek kreas = meat) is an amino acid derivative naturally present in our body.
In male subject of 70 kg, the amount of body creatine amounts to about 120g; this concentration increases as the muscle mass of the subject increases.
Creatine is present in food of animal origin, especially in meat and fish, but it is also produced within our body. In particular, it is synthesised at liver, kidney and pancreatic level, using the amino acids Arginine, Glycine and Methionine.
Once synthesised or taken through the diet, creatine is captured from muscle tissue and stored there.
Phosphorylated in phosphocreatine, creatine constitutes one of the muscle energy deposits.
It is therefore used as needed during rapid and intense muscle contractions.
The human body consumes about 30 mg of creatine per kg of body weight per day, on average 1.5 – 2% of its body reserves.
The “degraded” amount of creatine is eliminated through urine in the form of creatinine.
The share of creatine needed to compensate for the losses evidently increases in proportion to the muscle mass and intensity of the exercise performed.
Fortunately, an adequate diet can easily compensate for the amount consumed, and thus satisfy even the most intense needs. creatine
The daily creatine requirement is therefore about 2 g (1.5% of 120 grams) and is met through endogenous synthesis (1 gram/day) and diet.
Meat and fish contain a fair amount, but they lose a good percentage during cooking.
Creatine introduced with the diet does not change during digestion and is incorporated mainly in skeletal muscle (95%), in free form (40%) and in the form of creatine phosphate or phosphocreatine (60%).
The French chemist Michel Eugene Chevreul (Angers 1786-Paris 1889) isolated creatine from meat broth.
In 1847, Lieberg’s studies confirmed that creatine was a normal constituent of meat.
In addition, Lieberg observed that the flesh of wild foxes contained ten times more creatine than that found in the muscles of foxes kept in captivity; he concluded that motor activity increases the muscle concentration of creatine.
From a metabolic point of view, creatine intervenes to meet the energy demands of the anaerobic lactic mechanism.
The anaerobic lactacid anaerobic mechanism is the energy mechanism that is activated as soon as intense muscular effort begins. This process involves a single chemical reaction and allows for immediate energy availability.
PC + ADP = C + ATP
PC= CREATINE PHOSPHATE (or phosphocreatine); it is synthesised at rest in skeletal muscle by combining a creatine molecule with an inorganic phosphate molecule.
ADP = adenosine diphosphate
C = creatine
ATP = adenosine triphosphate
The enzyme that catalyses the reaction is creatine kinase.
At the end of this reaction, it converts part of the creatine back into phosphocreatine; part of it is converted into a waste substance, easily dosed in blood and urine, known as creatinine.
Oxygen is not used in this energy mechanism, which for this reason is called anaerobic.
The lactic agentive, on the other hand, emphasises that there is no lactic acid production during the reaction.
As we have said, this system has a very short latency, high power but low capacity. It means that it activates quickly, it generates large amounts of energy in the unit of time, but it runs out very quickly.
The phosphocreatine reserves, in fact, are exhausted within 4-5 seconds, although the amount of creatine phosphate in the muscles is variable and increases with training.
During intense muscle activity of very short duration, the decrease in strength developed is directly related to the depletion of muscle reserves of phosphocreatine.
Why do you use creatine? What’s it for?
Creatine is widely used in sports as an ergogenic aid, although recent evidence has also characterised a very interesting antioxidant, cardioprotective and neuroprotective activity.
Creatine has also been successfully used in clinical settings, in pathologies such as muscular dystrophy, amyotrophic lateral sclerosis, sarcopenia, cachexia and in heart failure.
Properties and Effectiveness
What benefits has creatine shown in studies?
Contrary to what one might think, especially considering the very important biological role of creatine, the studies published in the literature still show very conflicting data about the real usefulness of this supplement, both in sports and in the clinical field.
Creatine and sport
Most of the studies have focused on the potential ergogenic role of creatine in exercises and sports with a high intensity of performance.
According to some authors, an appropriate supplementation protocol would ensure:
An appreciable increase in creatine muscle concentrations, sometimes by almost 20%;
An improvement in contractile capacity and neuromuscular function;
An increase in critical power, i.e. the maximum power exerted in an exercise before the sensation of fatigue is triggered;
A reduction in the sensation of fatigue.
These data were collected under ideal “laboratory” conditions difficult to reproduce in a normal training session or race.
Complicating the picture on the efficacy of creatine in sports would result from some work according to which, following a careful re-reading of over 71 clinical trials published in the 1990s, no significant improvement in performance after creatine supplementation would emerge.
Creatine and body composition
Many studies seem to agree on the ability of creatine to determine alterations in body composition.
However, the much-coveted muscle gain associated with creatine intake, boasted by various sources, would be a blunder, as it results from increased intracellular fluid content (as observed by impedance data).
Creatine and neuromuscular diseases
Preliminary studies have tested the usefulness of creatine in the management of complex neuromuscular diseases, such as amyotrophic lateral sclerosis.
According to partial data, adequate creatine supplementation appears to improve motor performance testing in affected patients.
The mechanisms of hypothesised would involve both the ergogenic and antioxidant activity of creatine.
Doses and mode of use
How to use creatine
Over time, there have been several protocols for the intake of creatine monohydrate, especially in sports.
From a careful examination of the scientific literature, there are two protocols most used in sports.
The first consists in the intake:
20g of creatine per day (or 0.3 g per kg of body weight), divided into at least 4 administrations per day, for 2-5 days (loading phase);
at the end of the loading phase, 2g of creatine per day for the following 4 weeks (maintenance phase).
The second intake protocol comprises a daily intake of 3-6 g, without loading and maintenance phase.
According to some authors, the second protocol would guarantee in the long term the same effects as the first, in terms of improvement of anaerobic performance at high intensity, with a lower risk of side effects, especially of gastro-enteric nature.
In both protocols, to optimise its bioavailability, creatine should be taken with simple sugars.
In the light of some evidence that endogenous creatine production and muscle storage capacity would be reduced during the use of creatine supplements, it is currently suggested to interval the intake periods with resting phases of at least 4-6 weeks.
Creatine, Glucose and Protein
Studies carried out in recent years have shown that the absorption of creatine is increased by the simultaneous administration of carbohydrates with a high glycemic index, such as glucose.
Insulin is in fact able to increase the passage of creatine from the circulatory stream to muscle cells. However, in order for the insulin response to be maximum, about 20 grams of glucose per gram of creatine must be taken, which can be dangerous for people suffering from insulin resistance and type 2 diabetes.
Generally, the carbohydrate dose is taken about 30 minutes after the creatine dose; in fact, the glycemic peak must be created when creatine has already been absorbed at enteric level and is in the bloodstream, ready to enter the cells.
It was then attempted to add to creatine supplements other molecules capable of increasing insulin production, such as chromium picolinate, alpha lipoid acid and some amino acids.
However, little attention was paid to the fact that proteins are also able to increase insulin production. The simultaneous intake of creatine, glucose and protein may therefore be the most effective solution to ensure maximum absorption of creatine.
Side effects related to inadequate creatine intake may be of different clinical magnitude in quantity or timing.
More precisely, excessive use of creatine may result in acute diarrhoea, cramp-like abdominal pain, skin rash and allergy-like symptoms.
Prolonged use of creatine over time may induce:
- An increase in blood creatinine concentrations;
- Dehydration and altered blood pressure;
- Weight gain;
- Muscle cramps;
Fortunately, very rarely is the incidence of severe adverse reactions such as renal failure and atrial fibrillation.
When should creatine not be used?
Using Creatine is contraindicated in patients with dehydration or impaired renal function (renal failure, nephrotic syndrome, other renal diseases or predisposing conditions).
The above contraindications would also extend to people hypersensitive to the active substance.
What drugs or foods can change the effect of creatine?
No noteworthy drug interactions between creatine and other active ingredients are currently known.
In sports, however, the muscle bioavailability of creatine could be enhanced by the concomitant intake of simple sugars.
Precautions for use
What do you need to know before you take creatine?
Using creatine supplements should be avoided during pregnancy and lactation, in pediatric age and in all cases of increased risk for kidney disease.
For this reason, in certain cases it would be appropriate to monitor the degree of renal function with your doctor before taking creatine.
Following the use of creatine, especially at high doses, there may be an increase in body weight, mostly linked to increased fluid retention.