V02 Max decrease from Beta 20.31

For me, since the previous 20.xx update, it drops rapidly during runs. However, my training theme has not changed, in fact I have improved recently, in the last 3 weeks. From 57, I'm already under 55. No illness or injury. I think that since the race prediction was made more precise, which has improved for me anyway, since then VO2 MAX has been decreasing.

I was 63 up to 10 days ago and dropped to 61 after last two firmware updates...any change on training apart some bike activity added and almost same pace with same HR and same power.....so they did change some parameter to calculate Vo2Max in the last 2 firmware updates

Mine hasn’t done that , in fact mine has increased slightly as my training has.

I use Runalyze to see the data from fit file to two decimals .

I see discrepancies with Runalyze eventough that APP gets data from garmin so the datas are wrong.....same distance, better pace, better HR and lower Vo2 Max....there is something wrong since 2 weeks in Garmin

Mine is almost the same . They interpret training differently, mine are currently :  59.93 vs 59.50 - it depends on the type of training and how they each interpret it.

Do you also look at the "from fit file VO2"? 

yes checked as is same you get from Runalizer but the calculation is done by Garmin so if they change way to calculate in the new release than we get different data....or maybe better to say if the HR or power etc are different than with previous firmware you get different V02 so I need to know what has changed in the last two weeks....unless is me perfoming worse but I doubt it....anyway will do a speed tests to check this

drop from 52 to 46 :)

Same here, no change in my training I was expecting to get back to my level from spring but since 4 weeks, I see a constant drop and have nearly lost 2 units. Quite annoying.

It is for sure a firmware bug. I run Sunday and got as of runalizer an increase of Vo2Max but Garmin keep lowering it and assign a not productive run since weeks…