Creatine is a highly energetic amino acid derivative present in many foods, especially in meat and fish (200 g of red meat provide approximately 1 g of creatine).
Creatine is synthesized by the liver from arginine, S-adenosyl methionine and glycine and in the phosphorylated form (phosphocreatine-PCr) has the task of transporting energy (ATP) into cells, improving muscle energy levels and reserves. About 95% of the creatine in the body is stored in skeletal muscle: two-thirds of this percentage is deposited as phosphocreatine (PCr), while the remainder is in free form.
Biochemically speaking, to regenerate ATP, during and after physical effort, energy is needed and this is released depending on how much PCr is available in the muscle.
As PCr stores are depleted during intense exercise, energy availability decreases due to the inability to resynthesize ATP in the amount required to continue high-intensity exercise. As a result, the ability to maintain a constant level of effort decreases.
With the increase in muscle creatine content, through its integration, the availability of PCr increases and consequently the speed of ATP resynthesis is increased during and after high-intensity, short-duration exercise.
Creatine, therefore, increases recovery capacity, gives muscles more volume, increasing the threshold of fatigue and energy, especially in the case of repetitive, high-intensity, short-duration activities.