How does VO2max "works" with different altitudes?

My VO2max was 53 at 0m altitude.

In November, i moved at 2300m of altitude and, slowly, my VO2max dropped until 50...nothing strange as it was expected.

Today, i did another run at 0m of altitude and the run was pretty bad(since i moved at 2300m i'm not training regularly and now, with holidays, etc it's also not easy to follow the daily suggestions regularly, etc).

I was expecting another drop in VO2max but to my surprise it went back to 53.

So, is there any explanation for this? Does it simply mean that with less air, the VO2max drops accordingly without changing suggested paces?

In that case, it would be nice to have 2 different values. One always projected at 0m and one based on the current altitude...probably a feature for a minority but it would be cool.

Something else more complicated?

0 Etupes25 over 2 years ago

As you said, VO2 Max is expected to decline with altitude increasing. About 6% down every 1,000m up.

"VO(2max) declined linearly from 66+/-1.6 ml kg(-1) min(-1) at 300 m to 55+/-1.6 ml kg(-1) min(-1) at 2,800 m corresponding to a 6.3% decrease per 1,000 m increasing altitude (range 4.6-7.5%)."

https://pubmed.ncbi.nlm.nih.gov/16311764/

You experienced a 5.7% drop from 53 to 50, much less than the 14.5% (10.6%- 17.2%) drop that this study would anticipate from 0 to 2300m. If we take into account the error rate, it is not that far from the lower limit, since VO2 Max is at best estimated with a 5% error.

0 Mladen T over 2 years ago in reply to Etupes25

Cool..pretty much my first "theory" and for that reason it would be really cool to get a "projection" of the VO2max at 0m as a reference

Time to submit a suggestion to Garmin i guess.

Etupes, thanks for the link

0 pac_71 over 2 years ago

While VO2max would vary by altitude I would think it unlikely the Garmin algorithm or the studies it is based upon accounts for that. If anything, it is likely based at sea level which possibly introduces a VO2max estimation error as the assumed conditions have changed.

However, the exercise physiology of running at altitude will affect the parameters the algorithm does use to estimate VO2max. eg less blood oxygen = less muscle capability = higher heart rate = running slower = lower VO2max