What is VO2max?
Oxygen flow gives an indication of performance level
During physical effort, our muscles need oxygen to function. Oxygen is used to transform energy stored locally in the form of glycogen into energy that can be used by muscle fibers. The oxygen supplied by the lungs through respiration is transported to the muscles by the blood via red blood cells.
VO2max (V for "volume", O2 for "oxygen", max for "maximum") is the abbreviation for "maximum oxygen consumption". It represents the maximum flow of oxygen that the body can consume during an effort.
It gives an indication of the athlete's level of fitness and endurance. The higher it is, the faster the athlete can go at a given intensity of effort.
VO2max represents potential aerobic power (oxygen use). This potential is never fully exploited. Depending on the degree of training, only part of it is. An untrained person uses no more than 50% of his or her potential (50% of VO2max): beyond that, the anaerobic pathway takes over, producing waste products in the blood - blood lactates - which exceed the body's capacity to eliminate them, preventing muscle function and affecting performance.
VO2max, a performance indicator
VO2 max gives an indication of an athlete's level of fitness and endurance. The higher its value, the more capable the athlete is of sustaining an effort of a certain intensity over time. If you increase your VO2max by training, you'll be able to run either faster for the same distance, or longer for the same intensity.
VO2max is considered to be a limiting factor in sporting performance. The volume of oxygen supplied to the body increases with effort, but beyond VO2max it can no longer increase (for a few seconds or minutes at most).
Equal VO2max does not mean equal performance
Other parameters come into play, such as physiology, energy resource management, stress management, etc., but also endurance. As a result, two athletes with the same VO2max will not necessarily perform in the same way, and will not finish the same event in the same time.
Anaerobic threshold, an endurance indicator
The anaerobic pathway (without the use of oxygen) is activated long before the VO2max threshold (aerobic potential power) is reached. The anaerobic pathway provides the muscles with energy to supplement that of the aerobic pathway. Above the anaerobic threshold (50 to 85% of VO2max), the production of blood waste products, lactates, exceeds the body's capacity to eliminate them, forcing the athlete to reduce speed. To maintain an effort over time, the athlete must work below or at the limit of the anaerobic threshold, which determines his or her endurance capacity.
The ability to maintain effort for as long as possible (at least for the duration of the event) and at optimal intensity (as high as possible) is called endurance.
Managing energy reserves
In long-distance events (ultra-trail, marathon, major cycling stages), running speed is important, but it's not enough to win. Runners must also manage their energy reserves to avoid being slowed or even stopped by hypoglycemia.
In short events (e.g. 2000 or 3000-meter run), the running speed corresponds to 100% of VO2max.
The Chester Step Test, which focuses on the submaximal criterion of effort, is based on the linear relationship between heart rate (itself related to exercise power) and VO2 . The V02max value can thus be estimated by measuring heart rate
