Table adapted from Fox E. L. et al, The Physiological Basis for Exercise and Sport, 1993

ATP- (Adenosine triphosphate) is the energy molecule of all living cells. Humans get energy from food; this energy must be converted to ATP before it can be used by the cells to carry out all necessary functions.  ATP is stored in the muscles and blood.

CP- (Creatine Phosphate): a chemical compound stored in muscle, which when broken down helps in the production of ATP. ADP and CP together produce ATP.

Muscle glycogen- is the main fuel during heavy and prolonged exercise and is only available in the muscle that stores it. Fatigue is linked with muscle glycogen depletion, even when fatty acids are available for fuel.

Lactic acid- provides fuels for many tissues in the body.  Lactic acid is formed during the breakdown of glucose to be used as energy when oxygen is low. The lactic acid system provides energy for high intensity activities lasting up to two or three minutes.

Fatty acids- are a major source of energy production at any time, except after a carbohydrate enriched meal, and they are the main nutrient utilized from fat stores in extended exercise (activity longer than 4 min).

When an athlete designs their strength and conditioning program it is necessary for the program to focus on development of their energy systems and sport specific skills.  Why is this important?  The development of your energy systems will have your muscles, nervous system, and hormones acting together in order to help your body work as efficiently as possible. When you learn a new skill the central nervous system will store the learned motor pattern for the future.  Each time you perform an exercise or a skill, the neuromuscular system continues to develop and build upon the previous experience. Frequent practice of sport specific exercises will create more neuro pathways which are essential for an athlete’s progression.  George Liset says in the article on sensory motor learning that “as an athlete begins to refine a skill, the information is fed back and forth between the brain and the senses until a successful and coordinated pattern of action is formed. This development may be accelerated by stimulation and may be slowed by injury or lack of stimulation. There is an orderly progression in the development of these abilities. Unnecessary and counterproductive muscular movement in the body is detected and weeded out. The movement gradually becomes more refined and efficient over time. Information is exchanged.”