What is maximal oxygen uptake (VO2 max)?

From the Guidelines

VO2 max is the maximum amount of oxygen your body can use during intense exercise, representing your cardiorespiratory fitness level and measured in milliliters of oxygen per kilogram of body weight per minute (ml/kg/min) 1.

Definition and Measurement

VO2 max indicates how efficiently your body can take in oxygen through your lungs, transport it via your bloodstream, and use it in your muscles. This measurement varies based on factors like age, gender, genetics, and training status.

• It is influenced by age, sex, exercise habits, heredity, and cardiovascular clinical status 1.
• A higher VO2 max generally means better aerobic fitness and endurance.
• Athletes typically have higher VO2 max values than non-athletes.

Improvement and Testing

You can improve your VO2 max through regular cardiovascular exercise, particularly high-intensity interval training.

• Testing for VO2 max usually involves exercising at increasing intensities while wearing equipment that measures oxygen consumption, though there are also field tests and estimation formulas available 1.
• Improving your VO2 max can enhance your exercise performance and overall health by increasing your body's efficiency in using oxygen.

Clinical Significance

VO2 max is considered the best measure of cardiovascular fitness and exercise capacity 1.

• It represents the amount of oxygen transported and used in cellular metabolism.
• One metabolic equivalent (MET) is a unit of sitting/resting oxygen uptake (3.5 mL of O2 per kilogram of body weight per minute).
• Endurance training can augment VO2 max by 10% to 30% primarily by increasing maximal stroke volume and aV˙ O2 difference 1.

From the Research

Definition of Maximal Oxygen Uptake (VO2 max)

• Maximal oxygen uptake (VO2 max) is the oxygen uptake attained during maximal exercise intensity that could not be increased despite further increases in exercise workload, thereby defining the limits of the cardiorespiratory system 2
• It is regarded by some as the best single measurement of aerobic fitness 3
• VO2 max is a valid index measuring the limits of the cardiorespiratory systems' ability to transport oxygen from the air to the tissues at a given level of physical conditioning and oxygen availability 2

Determinants of VO2 max

• The ability of the cardiorespiratory system to deliver oxygen to the exercising muscles is the primary limiting factor for VO2 max in exercising humans 4
• Training-induced increases in VO2 max are largely facilitated by expansion of red blood cell volume and an associated improvement in stroke volume 5
• Variations in VO2 max improvements with exercise training are also likely related to variations in these physiological determinants 5

Measurement of VO2 max

• VO2 max can be measured during incremental exercise tests or supramaximal exercise tests 2
• The velocity at VO2 max (vVO2 max) is a useful variable that combines VO2 max and economy into a single factor which can identify aerobic differences between various runners or categories of runners 6

Relationship with Endurance Performance

• VO2 max is an important variable that sets the upper limit for endurance performance 4
• Running economy and fractional utilization of VO2 max also affect endurance performance 4
• The speed at lactate threshold (LT) integrates all three of these variables and is the best physiological predictor of distance running performance 4