Cardiorespiratory fitness refers to the

Benefits of endurance activities that require the heart to work at maximal capacity in an effort to strengthen cardiac muscle.

Level of cardiac functions that are required to sustain blood pressure and blood flow through the arterial components during exercise bouts.

Outcomes of regular exercise relating to the ability to supply oxygen to skeletal muscle during sustained physical activity.

Improvement in heart rate that the body is capable of as it increases exercise duration with each session of endurance activity.