The body has three energy systems.
They are:
- The Phosphagen System - Provides short bursts of energy. Fatigues quickly, under 15 seconds, does not require oxygen, "anaerobic", or "without oxygen". Phosphocreatine converts to adenosine tri-phosphate (ATP) and is utilized for energy when required. Used for Power-based exercise.
- The Glycolytic System - Provides short to intermediate bursts of energy lasting up to three minutes. Uses glucose derived from the carbohydrates we eat to form glycogen. Glycogen is stored in the muscles and liver. It is converted to adenosine tri-phosphate (ATP) and utilized for energy when required. Does not require oxygen. By product is lactic acid which restricts conversion of glucose to ATP and prevents muscles from contracting. Used for power-endurance exercises.
- The Oxidative System - Provides long term energy for the body lasting up to three hours. This system uses oxygen, carbohydrates and fats as fuel. The rate of removal of lactic acid is faster than the rate of production which leads to longer exercise times. Used for distance exercises.
