Cardiorespiratory fitness is the ability of the circulatory and respiratory systems in the body to supply oxygen to the muscles during physical activity. Improved cardiorespiratory fitness enables the heart to better pump blood and increases the amount of oxygen that is distributed throughout the body. Good cardiorespiratory fitness reduces the risk of heart disease, diabetes, and stroke.
The main measurement of cardiorespiratory fitness is maximal oxygen consumption (VO2max). VO2max reflects how effective the oxygen transport system is able to move blood and how effective cells throughout the body are able to take in and use oxygen in energy production. It is usually tested during exercise to evaluate an individual’s overall physical fitness and endurance.