Vo2 Max dropping, but getting faster/better at running

something skews the equation i feel. i also started actually getting better and better and still vo2 lowers, LT drops, mad. try runalyze, just connect garmin account to it, i tryst it much more than garmin calcs. that may show you totally different picture, worth validating at least.

VO2 calculation derived from watch data.

https://www.firstbeat.com/wp-content/uploads/2017/06/white_paper_VO2max_30.6.2017.pdf

Interesting paper but it might be missing details.  Sometimes by VO2 changes purely with a weight change.

That seems to suggest what ive suspected as well in that it generally ignores elevation/inclination changes.  I always get higher VO2max estimates or increases on a flat run than my usual undulating routes.

What i do fine though are sprints always promote an increase for me,  threshold runs can do also but to a lesser degree.  Base runs nothing BUT when i do a slow club run with others this pretty much always causes a downward trend in the VO2Max.

There's quite a bit of information to be found online. That paper is from 2017 and Firstbeat Analytics engine will have developed along with Garmin's sensors since.

https://support.garmin.com/en-GB/?faq=lWqSVlq3w76z5WoihLy5f8

In that link, it explains that only outdoor GPS enabled activities are used to update VO2 max estimates. I didn't know until I read it, but there's an additional criteria about HR level and time...

Heart rate must be elevated to at least 70% of your maximum heart rate for at least 10 minutes continuously (15 minutes for some watches).

Some watches use accelerometer data for trail runs and I know that weight is definitely a factor. Absolute data is difficult to find as it's proprietary information. 

https://www.garmin.com/en-GB/garmin-technology/running-science/physiological-measurements/vo2-max/

There's also the fact that blood oxygen levels can only accurately be found in controlled lab measured tests so a GPS timed run with wrist or even chest strap HR alongside weight will be an approximation.

It's a metric I'm very interested in as it gives a longer term view of my health and trends, having tracked it for close on 10 years. I use it as a comparative value over months based on historical data to monitor general health and training efficiency.

I reached my holy grail of 50 last year, popped a calf and had to rest. I run at least 5k every day with threshold and intervals thrown in and I'm still struggling to improve on 46 in the last 6 months. I check it using the watch 'Training Status' and scroll down to VO2 max. It gives a more detailed graph than anywhere on Garmin Connect.

For best results, use a chest strap HRM and get stuck in to those interval sessions. Long runs at quicker pace do it for me alongside interval sessions but to much and I break.

I've long since concentrated on the actual activity over metrics but that's maybe because my numbers are over the hill these days. Saying that, I get much more satisfaction than I used to and can still break the occasional PB regardless of my dwindling VO2 max.

There's also the fact that you may be in very good shape and any less intense session is a slight regression on recent efforts alongside fluctuation in HR measurements to do with humidity, temperature or general health on the day.

Good luck with your training.

1741957 said:

Yet VO2 is still 51 and now 50

Usually, it can be that your VO2 max was 50,50, and in the long run, you get tired and your body can't perform better than in a short run. Why the algorithm doesn't correct it is another question. You are getting 50,49 - it's enough to round it to 50 in the watch. More info can be found in the activity file or if you sync to a service like runalize.com

VO2max is also HRV depended, not only pace and heart rate.

That means, the algorithm detects for example, that at heart rate 150 and pace X your HRV decreased.

Your heart beats is not so "elastic" and fresh as the days before.