Creatine supplementation and muscles: From metabolism to medical practice

Abstract

Creatine has become the most popular dietary supplement in sport and exercise physiology. In humans creatine is synthesized by the kidneys, pancreas and liver and transported mainly into brain, skeletal and cardiac muscle. Phosphocreatine is a high-energy content molecule, essential for the ADP to ATP conversion during intensive physical activity. Creatine and phosphocreatine are crucial in the energy shuttle system of high-energy phosphates between the mitochondrial ATP production and the cytosolic ATP consumption. Creatine supplementation increases lean body mass acting on myogenic regulatory factors. During muscular recovery, creatine supplementation regulates the regeneration process by reduction of muscle damage-induced inflammation and oxidative stress, activation and proliferation of satellite cells and regulation of calcium transport in muscle. The effects of creatine supplementation on muscle physiology are beneficial in anaerobic/aerobic exercises. In several muscle disorders (muscular dystrophies, in idiopathic inflammatory myopathies) creatine improved functional performance, but apparently not in metabolic myopathies; in McArdle diseases it may even have paradoxical effects. More research is warranted to better understand the short and long-term effects and safety of creatine supplementation among adolescents or elderly, as well as in different types of muscle diseases; for the two enzymatic genetic defects of creatine biosynthesis – arginine: glycine amidinotransferase (AGAT) and guanidinoacetate methyltransferase (GAMT), respectively – normal neurodevelopment has been achieved in early initiation of creatine therapy.

Keywords

• creatine supplementation
• creatine kinase
• muscle injury
• muscle regeneration process
• genetic nerometabolic disorders
• agat
• gamt