Creatine is a compound found naturally in the body. The liver and kidneys synthesize creatine. It is also obtained in the diet, ingested particularly in red meats. Creatine is important for energy metabolism, aiding with strength and intense short-term work requiring bursts of energy. Before starting a supplement such as creatine or a diet or exercise program, it is important to consult with a physician or other licensed healthcare professional.
Energy Metabolism
Foods are composed of micronutrients and macronutrients. Micronutrients are needed in small amounts and include vitamins and minerals. Macronutrients are needed in large amounts and include fats, proteins and carbohydrates. These substances are broken down, and the energy contained in their chemical bonds is used to form adenosine triphosphate or ATP. ATP is the main energy carrier of cells, including muscle cells. It is composed of the chemical base adenine, linked to a sugar molecule, which is linked to three phosphate groups. ATP provides energy by donating a phosphate to form ADP, adenosine diphosphate, which has two phosphate groups. It can then be further broken down or regenerated.
Strength and Muscle Hypertrophy
The functional parts of muscle cells that actually contract are made of proteins, such as actin and myosin. Actin and myosin interact to shorten muscle cells and contract the muscle. This process of contraction requires energy that ATP supplies. Challenging the muscle tissue with bodybuilding causes the individual cells to add proteins, making the cells --- and ultimately the muscles --- larger and stronger.
Biochemistry of Creatine
Creatine is found in very energy-dependent cells such as in muscle and brain tissue. In the cell, phosphate is added to creatine to convert it into creatine phosphate. When muscle cells contract and convert ATP into ADP for reuse. In addition, creatine enhances the formation of polyamines, strong growth-promoting substances. Since it provides energy and the synthesis of muscle protein, bodybuilders commonly use it.
Results
Creatine supplements tend to be most useful for exercise of short duration and high intensity. No studies indicate its use in endurance activities. In a large 2002 study in the "Journal of Family Practice" involving men under age 36, creatine supplementation increased the maximum weight of the squat and bench press. So far, women and older men have not demonstrated a signficant increase in strength.
References
- "Lehninger Principles of Biochemistry"; David L. Nelson, et al.; 2004
- "Physiology"; Linda S.Costanzo; 2008
- "Journal of Family Practice"; Does oral creatine supplementation improve strength? A meta-analysis; Dempsey et al; 2002
- "UpToDate"; Non-hormonal performance enhancement; David Baron; 2011
- "UpToDate"; Creatine: Natural drug information; LexiComp; 2011
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