Energy Systems Adequate energy is the basis for all sport whether it be endurance, strength or a combination.
Energy is the capacity to do work.
The human body has chemical, electrical, radiant and mechanical energy systems. In the human body we can measure energy in terms of heat using a kcalorie. The phosphagen system supplies ATP to the muscle cell for immediate energy. All other systems work to support this, however their rate of ATP production is much slower, thus explosive bursts of strength or speed deplete ATP within 30 seconds. However, PC's content is also limited in the cell so the combined available energy from these two products may last for around two minutes.