VO2max, Not Threshold Percentage, Sets the Level
Endurance athletes have been sold the same model for years: VO2max is one thing, but what counts is the percentage of it held at threshold. Fractional utilisation. That percentage was supposed to separate the professional from the age grouper, because VO2max is said to be largely genetic while threshold responds to training.
Johansen’s Norwegian group took test data from 292 athletes and checked it properly. The results appeared in the International Journal of Sports Physiology and Performance in 2025.
Three levels, one percentage
The sample held 71 elite athletes, 158 at national level and 63 at regional level. Distance runners, cyclists and cross country skiers, 212 men and 80 women in total.
| Level | Lactate threshold (% VO2peak) | VO2peak (ml/kg/min) |
|---|---|---|
| Elite (n=71) | 78.9% (±6.4) | 71.1 (±6.5) |
| National (n=158) | 79.9% (±6.7) | 65.5 (±8.0) |
| Regional (n=63) | 80.3% (±7.1) | 58.1 (±6.4) |
The percentage column shows no difference at all. The regional athletes even came out marginally higher than the elite. Statistically that is noise, but the direction says something.
The difference sits in the neighbouring column. Between elite and regional there are 13 points of VO2peak, and that is the number that separates the groups significantly. Speed and power at threshold differed too, but they tracked VO2max and economy directly.
Why the old model took hold
It was built on homogeneous elite groups. When everyone in a study sits around a VO2max of 70, all that separates them is the percentage at threshold and their economy. In a sample like that, fractional utilisation looks like the key to performance.
Widen the sample to national and regional level and the parameter stops separating anybody. VO2max is what remains.
The authors add something that is rarely stated this plainly. Lactate threshold as a percentage of VO2max is hard to shift with training. The range in each of the three groups ran from roughly 70% to 90%. It reads as an individual characteristic rather than a marker of progress.
How much economy can make up
Gabriele Gallo of KnowledgeIsWatt offered a practical approximation while discussing the study. A cyclist can compensate for at most five to seven points of VO2max through economy and fractional utilisation. That figure does not come from the publication, it is a practitioner’s conclusion, so it is an order of magnitude rather than a measurement.
An athlete at 75 can race someone at 80. An athlete at 68 will never beat someone at 80 on economy alone. Those two parameters vary far less than VO2max does.
Economy matters, but it has a ceiling.
That is not an argument for neglecting it. Strength training is one of the few documented ways to improve running economy and gross efficiency on the bike. The other is simply doing a large volume.
Tracking VO2max without a lab
The goal is a high VO2max, not a number for it, and those are different things.
Five minute power tracks VO2max reasonably well. A change in ramp test result usually follows a change in VO2max, so a turbo ramp works as a rough monitor. For setting FTP it is poor.
There is a catch. Better five minute power or a better ramp on short steps can come from an improved anaerobic reserve rather than a genuine rise in VO2max. Test design matters.
Garmin’s VO2max estimate is a separate matter. The algorithm pulls in heart rate, which makes little sense in this context. No training plan should be built around that number.
For a trained athlete a laboratory VO2max test has limited training value anyway, because the number alone says nothing about how to structure sessions. A lab pays for itself elsewhere: comparing race shoes, or checking what a position change did to efficiency.
What to do with this
Three conclusions, in order of importance.
First, stop treating the percentage at threshold as a measure of progress. It does not move and it does not separate athletes.
Second, VO2max is underrated in triathlon, particularly over long distance. The repeated claim that it stops mattering at IRONMAN does not hold up in this data.
Third, working on VO2max does not mean abandoning volume.
Mølmen, Almquist and Skattebo published a systematic review with meta regression in Sports Medicine in 2024. It covered data from 5973 participants across 353 studies on mitochondria and 131 on capillarisation.
The mitochondrial conclusion is unambiguous. The increase was similar for low intensity continuous training (23%), high intensity work (27%) and sprints (27%).
Capillarisation gives a different picture, and that is the important caveat. Capillary density rose only after continuous training (13%) and high intensity work (7%), and clearly more after the former. Sprints produced nothing here.
It is not the case that zone 2 builds only mitochondria while VO2max work builds only VO2max. On the vascular side, though, volume has an advantage that intensity cannot buy.
Anyone doing four by four minute intervals and wondering whether that is too far above threshold has the question backwards. The session raises the ceiling rather than the percentage of it.
Read next: Brick Training: How to Beat Heavy Legs. Racelify lists triathlons worldwide, each with a link to the organiser.