We get tired after exercise because our muscle fibers get tired very quickly. This is due to the major source of energy for the muscle tissue, called adenosine triphosphate, or ATP. As the muscles make use of this supply of energy, they get tired and fatigue.
<em>Your answer is:</em>
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B. Being at least 15 percent underweight.
Hope this helps C:
D. leg swings , foward bends , arm rotations , and neck extensions have nothing to do with sprinting
