Editing VO2 max (section)

===Measurement===
[[File:Ergospirometry laboratory.jpg|thumb|VO<sub>2</sub> max measurement using instruments on a metabolic cart during a graded treadmill exercise test]]
[[File:Gas_exchange_during_max_test.jpg|thumb|Gas exchange of VO<sub>2</sub> and VCO<sub>2</sub> during max test. Begin for 3 minutes at 60 watts and add 35 watts every 3 mins until exhaustion.]]
[[File:VO2 max Toulouse.jpg|thumb|Photo of a VO<sub>2</sub> max test]]

Accurately measuring V̇O<sub>2</sub> 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 in which exercise intensity is progressively increased while measuring: 
* [[Ventilation (physiology)|ventilation]] and 
* oxygen and carbon dioxide concentration of the inhaled and exhaled air.

V̇O<sub>2</sub> max is measured during a [[cardiopulmonary exercise test]] (CPX test). The test is done on a [[treadmill]] or [[cycle ergometer]]. In untrained subjects, V̇O<sub>2</sub> max is 10% to 20% lower when using a cycle ergometer compared with a treadmill.<ref name=Kaminsky2017>{{Cite journal |last1=Kaminsky |first1=Leonard A. |last2=Imboden |first2=Mary T. |last3=Arena |first3=Ross |last4=Myers |first4=Jonathan |date=2017 |title=Reference Standards for Cardiorespiratory Fitness Measured With Cardiopulmonary Exercise Testing Using Cycle Ergometry: Data From the Fitness Registry and the Importance of Exercise National Database (FRIEND) Registry |url=https://linkinghub.elsevier.com/retrieve/pii/S0025619616306243 |journal=Mayo Clinic Proceedings |language=en |volume=92 |issue=2 |pages=228–233 |doi=10.1016/j.mayocp.2016.10.003|pmid=27938891 |s2cid=3465353 |url-access=subscription }}</ref> However, trained cyclists' results on the cycle ergometer are equal to or even higher than those obtained on the treadmill.<ref>{{Cite journal |last1=Basset |first1=Fabien A. |last2=Boulay |first2=Marcel R. |date=2000-01-01 |title=Specificity of treadmill and cycle ergometer tests in triathletes, runners and cyclists |url=http://link.springer.com/10.1007/s004210050033 |journal=European Journal of Applied Physiology |volume=81 |issue=3 |pages=214–221 |doi=10.1007/s004210050033 |pmid=10638380 |s2cid=24902705 |issn=1439-6319|url-access=subscription }}</ref><ref>{{Cite journal |last1=Bouckaert |first1=J. |last2=Vrijens |first2=J. |last3=Pannier |first3=J. L. |date=1990 |title=Effect of specific test procedures on plasma lactate concentration and peak oxygen uptake in endurance athletes |url=https://pubmed.ncbi.nlm.nih.gov/2366529/ |journal=The Journal of Sports Medicine and Physical Fitness |volume=30 |issue=1 |pages=13–18 |issn=0022-4707 |pmid=2366529}}</ref><ref>{{Cite journal |last1=Costa |first1=M. M. |last2=Russo |first2=A. K. |last3=Pićarro |first3=I. C. |last4=Barros Neto |first4=T. L. |last5=Silva |first5=A. C. |last6=Tarasantchi |first6=J. |date=1989 |title=Oxygen consumption and ventilation during constant-load exercise in runners and cyclists |url=https://pubmed.ncbi.nlm.nih.gov/2770266/ |journal=The Journal of Sports Medicine and Physical Fitness |volume=29 |issue=1 |pages=36–44 |issn=0022-4707 |pmid=2770266}}</ref>

The classic V̇O<sub>2</sub> max, in the sense of Hill and Lupton (1923), is reached when oxygen consumption remains at a steady state ("plateau") despite an increase in workload. The occurrence of a plateau is not guaranteed and may vary by person and sampling interval, leading to modified protocols with varied results.<ref name="pmid23935584"/>