Creatine is a popular, legal supplement used for athletic performance enhancement. It increases the ability of the muscles to do work. However, it only works for certain types of activities. Consult with a physician before starting an exercise program and taking supplements.
Metabolism
Creatine is highest in meats, particularly red meats. This is because meat is a muscle, and creatine is stored in the muscle to improve strength. Creatine, as it pertains to performance enhancement, is taken as a supplement. It is absorbed through the digestive tract, where it travels to and is mostly taken up by muscle tissue. After it is used by muscle, it is metabolized to its waste product -- creatinine, which is excreted by the kidneys.
Cellular Energy
Adenosine triphosphate, or ATP, is the energy currency of the cell, including muscle cells. ATP provides the energy for muscle contraction. It is composed of a base, adenine, the sugar ribose and three phosphate molecules linked together. When muscle contracts, the ATP donates a phosphate and becomes adenosine diphosphate -- ADP. The harder a muscle works, the more quickly ATP is used.
Creatine Mechanism
Creatine rapidly regenerates ATP. When creatine enters the cell, it is converted to creatine phosphate. Creatine supplementation increases the amount of creatine phosphate in the cells. When ATP is used by the muscle cells and converted to ADP, creatine phosphate donates its phosphate to regenerate ATP. The ATP can then be used again to generate power.
Efficacy
Creatine works best for activities requiring short bursts of energy rather than long bouts of exercise. Strength training, power lifting and sprinting are examples of types of workouts that benefit from creatine. Creatine does not help with aerobic exercises, such as long-distance running.
References
- "Physiology"; Linda S.Costanzo; 2008
- "Lehninger Principles of Biochemistry"; David L. Nelson, et al.; 2004
- "Nutrition Concepts and Controversies"; Frances Sizer, et al.; 2007
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