Cardiorespiratory fitness

Cardiorespiratory fitness (CRF) refers to the ability of the circulatory and respiratory systems to supply oxygen to skeletal muscles during sustained physical activity. Scientists and researchers use CRF to assess the functional capacity of the respiratory and cardiovascular systems. These functions include ventilation, perfusion, gas exchange, vasodilation, and delivery of oxygen to the body's tissues. As these body's functions are vital to an individual's health, CRF allows observers to quantify an individual's morbidity and mortality risk as a function of cardiorespiratory health.

In 2016, the American Heart Association published an official scientific statement advocating that CRF, quantifiable as V̇O₂ max/peak, be categorized as a clinical vital sign and should be routinely assessed as part of clinical practice. Low levels of CRF have been shown to increase the risk of cardiovascular disease (CVD) and all-cause mortality. Some medical researchers claim that CRF is an even stronger predictor of mortality than smoking, hypertension, high cholesterol, type 2 diabetes mellitus, or other common risk factors.

Regular physical activity and exercise can improve CRF, thus decreasing risk of CVD and other conditions while improving overall health.