We spoke with Florian from SportMeetsScience about two fascinating concepts in endurance sports: VO₂max and fatigue resistance. What do they really say about performance – and why is it worth taking a closer look?
Enjoy the read!
-
What exactly is VO₂max and how is it measured in endurance sports? Are there any simple self-tests for a rough estimate?
VO₂max consists of several components. ‘V’ stands for volume, ‘O₂’ for oxygen, and ‘max’ for maximum. So it refers to the maximum volume of oxygen that an athlete can take in. You can imagine it like a balloon (our lungs): the larger the balloon, the more oxygen it can hold. Fortunately, we can increase this volume through training. This is important because our energy production is highly dependent on oxygen – without enough of it, we fatigue much faster.
VO₂max is ideally measured using what’s known as spiroergometry. This method measures the volume of oxygen passing through a valve while we are under (or applying) physical stress. It’s currently the most accurate method available. All other approaches, such as the Cooper test familiar from school or estimates from smartwatches, only offer a very rough approximation.
-
What are the limitations of VO₂max as an indicator of actual athletic performance?
VO₂max has several weaknesses. For example, it doesn’t seem to be very adaptable. That means someone could improve their performance while their VO₂max stays the same – or even decreases.
That’s because other factors also influence VO₂max: intra- and intermuscular requirements, mental aspects such as goal setting, and even individual fuelling strategies during long efforts. This has been shown in various studies comparing athletes with nearly identical VO₂max values but significantly different actual performance levels.
VO₂max is likely a more precise predictor for marathon performance than for the 1500m, which involves different demands.
-
What is fatigue resistance, and how does it differ from VO₂max?
Fatigue resistance is a theoretical concept that describes the ability to maintain a given level of performance over time.
As the definition implies, it cannot be directly measured. It describes performance stability after, for example, a prior effort, whereas VO₂max measures the maximum amount of oxygen the body can process. Fatigue resistance is influenced by factors such as intensity, duration, nutritional status, and environmental conditions. Currently, there is no standardised method for assessing it.
-
Can fatigue resistance be measured or at least practically estimated?
The challenge with fatigue resistance is that it’s still a relatively new concept. That means we don’t yet fully understand how it develops or how to train it. There is a lack of standardised measurement methods at the moment.
-
What role do VO₂max and fatigue resistance play in different endurance sports?
It’s hard to say definitively, especially as our understanding of fatigue resistance is still in its infancy. Some early articles are working on improving the methodology, but it remains complex. VO₂max is more clearly defined and measurable, but oxygen uptake is only one part of overall performance.
In running, oxygen uptake likely plays a larger role than in cycling, since running activates more muscles. As a rule of thumb: the more muscles involved in the movement, the greater the contribution of VO₂max to performance.
-
How do VO₂max and fatigue resistance develop through training – and can both be improved specifically?
There are several ways to improve VO₂max. Interval training and hypoxic training, for example, tend to have a positive effect. However, genetics also play a role.
With fatigue resistance, as mentioned, we still lack sufficient research to make concrete recommendations.
-
What role do nutrition, mental strength, and recovery play in fatigue resistance?
At this stage, it's difficult to assess. But it's likely that they are connected to some extent.
-
Conclusion: Why shouldn't we get obsessed with numbers like VO₂max?
As mentioned, VO₂max is only one part of performance. That means it isn’t everything. If we focus too much on individual metrics, we may lose sight of the bigger picture – and that could be a disadvantage in the long run.