VO2max represents the maximum rate of oxygen consumption by an individual during intense physical effort. It serves as a key indicator of performance level in endurance sports. But how is it determined? What are typical values? And how does it relate to MAS? Here are some insights.
What does ‘VO2max’ stand for?
The ‘V’ in VO2max stands for ‘volume,’ explaining its designation as VO2max (with a ‘V’) instead of using a feminine article as in French. ‘O2’ denotes the oxygen molecule, crucial for combustion processes.
‘Max’ signifies the peak volume. Technically, there is a dot above the ‘V’, denoting the derivative of volume per unit of time, which equates to a flow rate. Thus, VO2max is the maximal rate of oxygen consumption by an individual. It is quantified in milliliters per minute (mL/min).
In sports, the power-to-weight ratio is critical for assessing performance. As a result, VO2max is often divided by the athlete’s weight and expressed in mL/kg/min.
VO2max is influenced by various physiological and anatomical factors. It mirrors the ability of the respiratory and cardiovascular systems to transport oxygen to muscle cells, facilitated by the blood and red blood cells.
Is there a connection between MAS and VO2max?
In the realm of running, the term MAS (Maximum Aerobic Speed) frequently surfaces. Also known as vVO2max (velocity at VO2max), MAS is the minimum speed at which a runner attains their VO2max. Typically, a runner can sustain their MAS for about 4 to 7 minutes, although this duration varies based on individual characteristics. In cycling, the analogous term is MAP (Maximum Aerobic Power).
A notable connection exists between VO2max and MAS, encapsulated by the “Léger formula”: VO2max = MAS x Cr, where Cr represents the energy cost or running economy, measured in mL/kg/km. This energy cost differs among runners, with a commonly accepted average value being 210 mL/kg/km. This leads to the equation VO2max = 3.5 x MAS. A lower running economy (energy cost) implies that a runner expends less energy and is more efficient. Elite Kenyan and Ethiopian runners, for example, often exhibit a running economy around 180 mL/kg/km (equivalent to a coefficient of 3).
In this context, VO2max can be seen as the runner’s ‘engine’. In contrast, MAS reflects the engine’s efficiency, influenced by factors like posture, relaxation, stride quality, and muscle quality.
The formula VO2max = 3.5 x MAS is, however, a theoretical estimate.
For instance, during a treadmill test I conducted, I achieved a VO2max of 72 mL/min/kg and my MAS was 23 km/h. This indicates an energy cost of 188 mL/kg/km (or a coefficient of 188 / 60 = 3.13).
Using this formula, my estimated VO2max would have been 81 mL/min/kg. Hence, it's crucial to perform a laboratory test for an accurate measurement of maximum oxygen uptake, as these calculations are merely estimative.
How to perform a VO2max test?
The most reliable method to determine your VO2max involves measuring the gas exchanges (oxygen and carbon dioxide) during respiration, typically using a specialized mask. This test is designed to push you to your maximum effort level. Given the extensive nature of the equipment required, conducting the test on a treadmill at a sports doctor's or physiologist's office is often more feasible.
However, advancements in technology have now made it possible to perform these tests outdoors while running, using compact, mobile devices. It's important to note that cardiologists, while they do assess the body's response to exercise, do not always measure VO2max. Their primary focus is on how the body, particularly the heart, adapts to exertion from a cardiac standpoint.
One common protocol for the VO2max test involves running in 2-minute increments. The test starts at 50% of the estimated MAS (Maximum Aerobic Speed), with the speed increasing by 1 or 2 km/h at each stage. Consequently, the VO2 level incrementally rises until the subject reaches exhaustion.
You'll know you've reached your VO2max when your VO2 stabilizes or plateaus towards the end of the test, despite increasing exertion. It's noteworthy for runners that if the test is performed on a bicycle, reaching your true VO2max may not be possible due to the power output being a potential limiting factor.
Sports federations, professional teams, and individual athletes often engage physiologists to administer VO2max tests in real-world settings. I have had the opportunity to undergo a VO2max test on a track, and my detailed experience is shared in this article.
These tests are invaluable in accurately determining one’s VO2max and other vital physiological metrics, such as paces at aerobic and anaerobic thresholds. A significant benefit is the ability to perform these tests in the athlete's regular training environment and in their sport of choice, whether it be running, cycling, skiing, etc.
Measuring anaerobic threshold using the respiratory quotient
A comprehensive VO2max test also measures the Respiratory Quotient (RQ) to determine the ratio between carbon dioxide output and oxygen consumption. This helps identify the type of fuel used during exertion, whether it's predominantly fats or carbohydrates.
If the respiratory quotient is too high at a low pace, it's necessary to focus on fundamental endurance running to improve fat combustion and increase capillaries. These small blood vessels that transport nutrients to the muscles.
When the Respiratory Quotient reaches 1, the body is using only carbohydrates. This typically corresponds to the anaerobic threshold. A runner or cyclist can maintain this speed or power for about 30 minutes to an hour, depending on their training level.
Above this speed, lactic acid does not recycle quickly enough and begins to accumulate. Therefore, it can be useful to measure lactate concentration below and above this speed to see if lactate levels are already too high. In such cases, the anaerobic threshold has already been reached, and the threshold is slightly overestimated. Lactate measurement is done with a small device and requires a drop of blood from the fingertip or earlobe.
What about the VO2 Max score provided by my watch?
The VO2 Max score given by your watch should be understood as an approximation, which may only be accurate for about 10% of individuals. The most dependable method to accurately determine your VO2max involves undergoing a maximal effort test that measures gas exchange. While your GPS watch may offer a VO2 Max estimate (often a feature that excites users: 'Look, my watch even gives me my VO2 max 😜!'), it is important to remember that this is still an approximation. At its best, this feature can be useful for tracking progress over time. However, it should not be relied upon as an absolute or definitive value of your VO2max.
What are the common values?
The maximum oxygen uptake depends on factors like gender, genetics, age, weight, smoking, and training level. While gender, genetics, or age cannot be changed, reducing weight, quitting smoking, and especially training (including interval sessions) are factors for improvement!
In general, men have a VO2 max between 40 and 50 mL/min/kg, and women between 35 and 45 mL/min/kg. More athletic individuals exceed 70mL/min/kg for men and 60mL/min/kg for women.
In one's lifetime, the VO2max peaks between 20 to 30 years and then declines by an average of 10% per decade. Training reduces this decline, and a sedentary person who starts exercising can increase their VO2max even after 30 years.
What are the VO2max records?
Endurance athletes typically exhibit the highest VO2max values. The record is believed to be held by Oskar Svendsen, a young Norwegian cyclist, with an impressive 97.5 mL/min/kg. Cross-country skiers often record values over 90 as well. Notably, ultra-trail runner Kilian Jornet achieved a VO2max of 89.5 mL/min/kg during a test in Barcelona.
American Frank Shorter, the 1972 Olympic marathon champion with a time of 2 hours and 10 minutes, had a VO2max of 71.3 mL/min/kg. This highlights the fact that running economy is equally crucial and can compensate for a relatively lower VO2max.
Among female athletes, the record is held by Joan Benoit, the 1984 Olympic champion, with a VO2max of 78.6 mL/min/kg. British marathon world record holder Paula Radcliffe, with a time of 2 hours and 15 minutes, also boasts a high VO2max over 70 mL/min/kg. Throughout her career, while her maximum oxygen uptake remained consistent, her running economy and thus her MAS (Maximum Aerobic Speed) significantly improved.
In summary, while knowing your VO2max is beneficial, it's not the sole determinant of running performance, as running economy plays a substantial role as well. Monitoring the evolution of your MAS over time, with consistent testing, is a more effective approach to gauge progress.
The RunMotion Coach app, offering tailored training, can aid in enhancing both your VO2max and MAS 👌The training involves a mix of short and long interval sessions, along with fundamental endurance workouts. These exercises induce physiological adaptations, particularly in the cardiovascular and muscular systems, contributing to overall athletic improvement.