VO2 Max Decreasing Despite Increasing FTP and Stable Weight

[mcalista]

@Weiwentg

The other thing is that there’s the concept of test-retest reliability. That is, in many settings, even if the underlying value doesn’t change, we would expect a test to produce slightly different results when administered repeatedly, just because of measurement error. We don’t know the test-retest reliability of the Garmin algorithm. It may be that the minimum detectable change is 1 mL O2/min kg. It may be that it’s more like 3 mL. We don’t know. But it’s not zero. And your VO2max estimates are within a band of 5-6 mL O2. That’s not a huge change.

The Firstbeat algorithm (which underlies the VO2Max estimate) had a white paper. It was noted there that the estimate was generally accurate to within about 5%. But that the accuracy declined significantly if you didn’t have an accurate HRMax number.