Powered By Three Energy Systems

When you exercise it is the muscles job to generate the large amounts of energy necessary to drive muscle contraction. You need to understand that in order for your muscles to produce energy rapidly and efficiently they must deliver the correct amount of fuel. Think of your muscles like an engine to a car. There has to be an interrupted supply of fuel in order for the car to drive. During exercise, there also has to be a continuous supply of fuel in order for the muscles to contract.

You must understand the process of which energy influences muscle contractions. Adenosine Triphosphate (ATP) is the only source of energy that can drive muscle contractions. An interesting fact is that muscles only store enough ATP for a few seconds of a maximal contraction. And as a result, ATP must be continuously replenished in order for muscle contraction to happen. Another interesting point is that at the rate of which ATP must be replenished is directly related to exercise INTENSITY! *The message is that the greater the exercise intensity, the greater amount of ATP requirement.

Understand that ATP can be produced by three different energy systems...2 of which are anaerobic (without oxygen) and one of which is aerobic (with oxygen).

ANAEROBIC ENERGY SOURCES: During high intensity exercise-your muscles replenish energy through Two (2) Anaeorbic Energy Systems.
1) Creatine Phosphate system- a high-energy phosphate compound that supplies energy for regeneration of ATP. However, muscles stores of creatine phosphate are very limited and there is only enough stored in the muscle to support a maximal effort for eight to twelve seconds.

2) Glycolysis- system that generates ATP by the breakdown of carbohydrate stored in the muscles as glycogen and blood glucose. But it cannot produce ATP as fast as the breakdown of Creatine Phosphate but is still considered a faster source than aerobic energy production. The other end of the glycoslysis is one of its byproducts, lactic acid- which is produced in high concentrations and can cause muscle fatigue and this result will affect performance.

AEROBIC ENERGY SOURCE: This energy source involves the use of oxygen for ATP production. It is slower than anaerobic processes but is much more efficient. This source is primarily used for exercise intensities that can be sustained for long periods of time such as running a marathon.
1) Aerobic metabolism takes place in small energy producing factories within the muscle cells called mitochondria. It uses oxygen along with fuels either stored in the muscles or stored elsewhere in the body to generate none other than ATP. So understand that the more mitochondria in the muscle, the more efficient the muscle will be in using oxygen to generate ATP.
*This source can use several different types of fuel, which include carbohydrates in the form of blood glucose and muscle glycogen, fats stored in adipose (fat) and muscle tissue, and amino acids (the building blocks of protein) taken from muscle protein.

The Performance Zone 2004(p.11-14)