🔬 What Is Creatine? Biochemical Basis
Creatine is a compound naturally produced in the body from three amino acids: arginine, glycine, and methionine. About 95% of creatine is stored in skeletal muscle, and the rest — in the brain, heart, and other tissues.
⚡ ATP-PC Energy System
The main function of creatine — ATP (adenosine triphosphate) regeneration. During short, intense exercise (1-15 sec), creatine phosphate (PCr) transfers a phosphate group to the ADP molecule, rapidly restoring ATP:
PCr + ADP → Cr + ATP
This allows muscles to maintain maximal intensity for longer. Supplemental creatine intake increases creatine phosphate stores in muscles 20-40%.
🧬 Creatine Synthesis in the Body and Sources
| Source | Creatine Content | Notes |
|---|---|---|
| Beef (500 g) | ~2.5 g | Best natural source |
| Chicken (500 g) | ~1.7 g | Less than in beef |
| Salmon (500 g) | ~2.3 g | Also contains omega-3 |
| Liver (500 g) | ~2.0 g | And many other nutrients |
| Body Synthesis | ~1 g per day | In the liver and kidneys |
| Creatine Monohydrate (5 g) | 5 g (99.9% purity) | The simplest and most effective form |
📚 Scientific Basis
The mechanism of creatine is one of the most clearly understood in sports nutrition: in muscles it is stored as phosphocreatine, which donates a phosphate group to the ADP molecule, rapidly regenerating ATP. This is exactly the energy pathway used in the first seconds after the start of high-intensity effort.
The first studies showing that creatine supplements can increase phosphocreatine concentration in skeletal muscle were published in 1992 (Harris et al.) — since then, creatine has remained one of the most researched sports nutrition supplements.
Source: Webb G. P., “Dietary Supplements and Functional Foods” (Blackwell, 2006) (p. 167); NSCA guide “Guide to Sport and Exercise Nutrition” (p. 52).
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