Find out all about VO₂ max in running

VO₂ max is the maximum amount of oxygen that the body can use per unit of time. To put it simply, it’s the amount of oxygen the lungs can inhale, transfer into the blood, and that the muscles then capture. It is expressed in two different units: in liters or milliliters of oxygen per minute (L/min) or per kilogram of body weight (mL/min/kg). The first is an absolute unit, while the second is relative or standardized, allowing for comparisons between two athletes of different sizes.

While sedentary adults have values around 30 to 40 mL/min/kg, elite endurance athletes (running, trail running, cross-country skiing, etc.) show record values in the range of 85 to 90 mL/min/kg. Between these two extremes, most runners—and perhaps you—fall between 40 and 65 mL/min/kg.

At this point, a question likely comes to mind: what is my VO₂ max? To find out, you would need to run (in a laboratory or on a track) equipped with a gas exchange analyzer capable of measuring your oxygen consumption at every moment. This is the type of effort you would provide if your doctor prescribes a stress test with a sports medicine physician.

However, truth be told, you are unlikely to ever know your precise VO₂ max through a direct measurement. This is not a problem: you won't use it daily in your training sessions. On the other hand, studies have shown that this VO₂ max value is associated with the maximal aerobic speed (or MAS) value, which is defined as the lowest running speed at which maximum oxygen consumption is reached. It is precisely this relationship between VO₂ max and MAS that interests us, especially since MAS can be easily evaluated through a progressive track test (Leger-Boucher test, Shuttle run test, TUB2 tests, etc.). Calculating your MAS should preferably be done with a coach on an athletics track.

VO₂ max is one of the key performance factors in endurance events. If this is your objective, you will therefore need to improve it, whatever the distance you are preparing for. A number of studies led by the French researcher Véronique Billat have shown that VO₂ max improves as you run to values close to MAS and especially the time spent at these values. In simple terms, the more time you spend at 95% (or higher) of the physiological values (heart rate, respiration) measured at MAS, the more you will improve your VO₂ max.

The first limiting factor is insurmountable: genetics. And you can do nothing about this, just like you will never be able to change your type of hair; we are simply not all the same, and VO₂ max is determined genetically, like many other performance factors. There are 5 limiting factors for each individual: ventilation, the transport of oxygen in the blood, the capacity of the heart to pump blood around the body, the capacity of the blood to reach the muscles and the capacity of the muscle to extract the oxygen. Some of the other limiting factors include age (your VO₂ max will decrease with age), sex (men's values are higher than women's) and altitude (10% reduction per 1,000 m of altitude).