User:Nufris10/Cardiorespiratory fitness

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.

History and Etymology
The emergence of a method to quantify CRF began in the 1920s when Archibald Hill, a British physiologist, proposed a multifactorial relationship between the maximum rate of oxygen uptake by body tissues and intensity of physical activity. This measure was found to be dependent upon functional capacities of an individual's cardiovascular and respiratory systems. He coined the term VO2 max, or maximal oxygen consumption, the numerical result of exercise testing that represents the maximum rate of oxygen consumed per kilogram of body mass per minute during exercise which now serves as the primary measure of CRF. This proposal ignited a multitude of studies demonstrating a relationship between VO2 max and cardiovascular disease (CVD) and all-cause mortality.

In 2016, the American Heart Association published an official scientific statement advocating that CRF be categorized as a clinical vital sign and should be routinely assessed as part of clinical practice.

The prefix "cardio-" refers to the heart while "-respiratory" links the heart and respiratory system, which includes organs that contribute to gas exchange in plants and animals, especially the lungs (animals). Fitness refers to an individual's state of health.

Measurement
Various methods of measurement exist for determining an individual's cardiorespiratory fitness. VO2 max is the most commonly accepted indicator of CRF and has been since the 1960s. Cardiopulmonary exercise testing (CPET) with spirometry is the gold standard for determining VO2 max. It requires the individual to perform exercise with analysis of gas exchange usually until maximal exertion is achieved. The use of electrocardiography is often used to examine heart response to exercise and exertion. CPET is performed on a treadmill or a cycle ergometer. The method of test administration is based on the abilities of the test subject, as the cycle ergometer is generally less taxing on the body and often better suited for elderly populations, although is shown to sometimes produce results 10% - 20% lower in individuals not accustomed to cycling due to leg fatigue.

In many cases, children or the elderly are not subjected to the vigor of cardiopulmonary exercise testing. There are other methods used to mathematically estimate the VO2 max of a test subject by having the subject achieve a certain distance in as little time as possible, complete the maximum number of repetitions of a short distance run, or walk on a treadmill at increasing incline until a sub-maximal goal is achieved, along with others.

Common forms of VO2 max measurement:

 * Bruce Protocol

-Exercise

-Benefits

-Medical Considerations

-Involved Organizations