VO2 max

VO2 max (also maximal oxygen consumption, maximal oxygen uptake, peak oxygen uptake or maximal aerobic capacity) is the maximum rate of oxygen consumption measured during incremental exercise; that is, exercise of increasing intensity. The name is derived from three abbreviations: 'V' for volume, 'O2' for oxygen, and 'max' for maximum. Maximal oxygen consumption reflects cardiorespiratory fitness and endurance capacity in exercise performance. VO2 max (also maximal oxygen consumption, maximal oxygen uptake, peak oxygen uptake or maximal aerobic capacity) is the maximum rate of oxygen consumption measured during incremental exercise; that is, exercise of increasing intensity. The name is derived from three abbreviations: 'V' for volume, 'O2' for oxygen, and 'max' for maximum. Maximal oxygen consumption reflects cardiorespiratory fitness and endurance capacity in exercise performance. VO2 max is widely used as an indicator of cardiorespiratory fitness. In 2016, the American Heart Association published a scientific statement recommending that cardiorespiratory fitness (CRF), quantifiable as VO2 max, be regularly assessed and utilized as a clinical vital sign. This statement was based on mounting evidence that lower fitness levels are associated with high risk of cardiovascular disease, all-cause mortality, and mortality rates stemming from various types of cancers. In addition to risk assessment, the AHA recommendation cited the value measuring fitness for validating exercise prescription, physical activity counseling, and improving both patient management and patient health. VO2 max is expressed either as an absolute rate in (for example) litres of oxygen per minute (L/min) or as a relative rate in (for example) millilitres of oxygen per kilogram of body mass per minute (e.g., mL/(kg·min)). The latter expression is often used to compare the performance of endurance sports athletes. However, VO2 max generally does not vary linearly with body mass, either among individuals within a species or among species, so comparisons of the performance capacities of individuals or species that differ in body size must be done with appropriate statistical procedures, such as analysis of covariance. Accurately measuring VO2 max involves a physical effort sufficient in duration and intensity to fully tax the aerobic energy system. In general clinical and athletic testing, this usually involves a graded exercise test (either on a treadmill or on a cycle ergometer) in which exercise intensity is progressively increased while measuring: VO2 max is reached when oxygen consumption remains at a steady state despite an increase in workload. VO2 max is properly defined by the Fick equation: The necessity for a subject to exert maximum effort in order to accurately measure VO2 max can be dangerous in those with compromised respiratory or cardiovascular systems; thus, sub-maximal tests for estimating VO2 max have been developed. An estimate of VO2 max is based on maximum and resting heart rates. It is given by: This equation uses the ratio of maximum heart rate (HRmax) to resting heart rate (HRrest) to predict VO2 max. The researchers cautioned that the conversion rule was based on measurements on well-trained men aged 21 to 51 only, and may not be reliable when applied to other sub-groups. They also advised that the formula is most reliable when based on actual measurement of maximum heart rate, rather than an age-related estimate.