You should now understand the cardiorespiratory system's response to exercise, in particular how this varies with exercise mode, duration, and intensity, and how this system is essential to delivering O2 to working muscles to allow continual production of ATP. Let's look at how to apply this knowledge to help clients increase their physical fitness. To develop appropriate exercise programs to enhance cardiorespiratory fitness, you must first understand the long-term adaptations to exercise training. So let's begin with how training adaptations are specific to exercise mode, intensity, and duration. Click Next to look at Frank's situation again.