Vo2 max running

Keep in mind garmin devices calculate your vo2max estimated value not the real number so always take it with a grain of salt. Usually garmin estimate is bit lower than real value, as ive seen. Garmin calculation is based mostly on your avg pace and avg HR. So different weather conditions like snow and wind could give false readings. Usually garmin devices tends to prefer higher paces so you would get better vo2max estimates over time by not doing warm up run and just go as fast as you can from the first second. Ofc its not recommended but its possible to cheat the algorithm that way. So its not perfect. I recommend you the site runalyze.com to see other estimate.

Mine has not updated for 6 months, despite significant improvements in 5k times and training structure. In my opinion, VO2max calcs are broken in the same way as lactate threshold. 

I started with a 7:08 pace and now my fastest pace is 6:37.

https://www.firstbeatanalytics.com/en/features/vo2max-fitness-level/

I also second using Runalyze , you can also in Runalyze see the Garmin data to two decimals - just select it in the view settings.  FWIW mine in RA and GC are within 5% of each other

I'm improving pace and VO2max is improving too

Do you by any chance do a lot of base training but no high intesity intervalls? This way the algorithm wont get your max HR and pace values.

If you just started running it may also be that your vo2max was not the limiter in the beginning and now your first improving your muscles but not your ability to metabolize oxygen. 

I do 1 or 2 high intensity interval trainings, 1 or 2 easy run and a tempo/fartlek per week, total 4 trainings and about 50km per week.

I run since 2 years and in 2021 my VO2max was around 45, with 61min on 10km (now 39).

I'm 47yo next may

I've found that VO₂Max figure goes down on longer, steady runs, but rises with shorter, faster runs.

For me, the threshold seems to be between 3km and 5km. A two mile run with increasing pace (negative splits) will usually bump up the score by a few hundredths, but a 15km run might have it dip by a similar amount.

Well, not true. In my previous post you can see VO2max line bumping up in the last day, when I did a easy run (for me) of 16km at 4:55/km in Z3