When challenged with any physical task, the human body responds through
a series of integrated changes in function that involve most, if not all, of
its physiologic systems. Movement requires activation and control of the
musculoskeletal system; the cardiovascular and respiratory systems provide the
ability to sustain this movement over extended periods. When the body engages
in exercise training several times a week or more frequently, each of these
physiologic systems undergoes specific adaptations that increase the body’s
efficiency and capacity.