Cardiorespiratory fitness

Cardiorespiratory fitness is the ability of the heart, lungs, and circulatory system to supply oxygen during sustained physical activity. It is commonly assessed by maximal oxygen uptake.

Maximal oxygen uptake: The highest rate at which the body can take up and use oxygen during intense exercise. It is the standard laboratory measure of cardiorespiratory capacity.
Cardiopulmonary exercise testing: An exercise test that measures respiratory gases alongside cardiovascular responses. It directly evaluates oxygen uptake and the systems that limit it.
All-cause mortality: Death from any cause within a defined population and period. Higher cardiorespiratory fitness is strongly associated with lower mortality risk.
Aerobic metabolism: Cellular energy production that uses oxygen to oxidize fuels. Sustained activity depends heavily on this oxygen-using source of energy.
Fick principle: A relationship stating that oxygen consumption equals cardiac output multiplied by the arterial-to-venous oxygen difference. It separates oxygen delivery by blood flow from oxygen extraction by tissues.
Six-minute walk test: A standardized test measuring the distance walked in six minutes. It estimates functional exercise capacity when maximal testing is impractical.
Cardiovascular disease: A group of disorders affecting the heart and blood vessels. Low fitness is linked to greater risk of cardiovascular illness.
Oxygen transport: The movement of oxygen from the lungs through blood to tissues. Fitness depends on each stage of this delivery pathway.
Cardiac output: The volume of blood pumped by the heart per minute, determined by heart rate and stroke volume. Greater exercise cardiac output can deliver more oxygen to active muscles.
Cooper test: A fitness test estimating aerobic capacity from the distance covered in a 12-minute run. It offers a field estimate of cardiorespiratory fitness without gas analysis.

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