The test
VO₂ max
The most oxygen your body can use while working hard. It is the single strongest measured predictor of how long you stay capable — and how you arrived at the number matters almost as much as the number.
What you need. A laboratory test with a mask, or an estimate from a watch, a gym test or a submaximal step test. The screen asks which you used.
How to do it
Doing it properly
- Use the best measurement you have.
- Say how you got it: a measured maximum, a measured peak that you did not push to a true maximum, or an estimate.
- If you have several, use the most recent one taken the same way.
What counts
Millilitres of oxygen per kilogram of bodyweight per minute. How you got the number matters as much as the number: an estimate is scored, but it widens the error around your Index and the screen tells you by how much.
What most people get wrong
- Entering a watch estimate as a measured maximum.
- Using a figure from a different test method than last time, which makes the two not comparable.
- Using an old number after a long change in training.
The wording of this protocol is Evolution’s own draft rather than supplied copy, and is marked as such inside the product too.
The evidence
What it actually shows
The reference is the FRIEND registry: 7,783 maximal treadmill tests with a peak respiratory exchange ratio of 1.00 or above, which is the marker that the effort was genuinely maximal. Your figure is placed against that distribution for your age and sex.
Most people arrive without a laboratory measurement, so the Index will take an estimate from a non-exercise equation — age, sex, body shape and self-reported activity. The estimate is scored against the same table as a measured value, so a person with one is never excluded.
The cost of estimating is stated rather than hidden. The equation has a standard error of 1.45 METs, roughly 5.1 ml/kg/min, and the Index scores your estimate at plus and minus that error against the same table. Half the spread between those two scores becomes the interval published beside your result — about ±15.6 Index points for a 52-year-old man, narrower for a fit 30-year-old, wider at the low end.
An estimate is not a measurement, and no amount of arithmetic makes it one. The interval is the honest size of the gap, not an apology for it.
The registry is made up of people who took a maximal treadmill test, which is not the same population as everyone. Laboratory reference sets of this kind skew towards people willing and able to run to exhaustion.
A measured VO₂ max needs a treadmill, a mask and gas analysis. It is the one test in the battery where the home version and the laboratory version are not close, which is why the estimate carries an interval three or four times wider than the tests you can do properly on your own floor.
Kaminsky LA, Arena R, Myers J. Mayo Clinic Proceedings 2015;90(11):1515–1523. FRIEND registry, 7,783 maximal treadmill tests, peak RER ≥ 1.00.
Jurca R, Jackson AS, LaMonte MJ and colleagues. Assessing Cardiorespiratory Fitness Without Performing Exercise Testing. American Journal of Preventive Medicine 2005;29(3):185–193, Table 5, NASA model. R=0.81, standard error 1.45 METs.
The next step
One test is one test.
This measures one thing. The Evolution Index measures nine, across the three domains that decide how long you stay useful, and reports your weakest rather than your average — a strong heart does not buy you out of a floor you cannot get up from.
Every score is published with the error around it, because a change smaller than the measurement error is not a change.