Why is my VO2 Max decreasing as I progress through Couch to 5k?

[swissfish]

A bit of context. I'm a 60 year old man who has never been particularly sporty, but after turning 60 in August I decided I needed to get fitter (a photo from the summer shows a definite belly on me!)

My wife and I started sessions with a personal trainer, and in November I decided to try the Couch to 5k program. My first run was on 22nd November and I successfully completed Week 6 this morning.

On 3rd November my Garmin connect app showed VO2 Max of 38 and told me I was in top 30% for my age and gender with a fitness age of 50.

This morning after my run I have a VO2 Max of 35, and I'm only in top 45% for my age and gender with a fitness age of 62.

What is happening? I was hoping to improve, not get worse

[Hidden]

I wouldn't worry about your VO2 reading too much, I also use a wrist garmin, and the figures fluctuate from run to run!

[IannodaTruffe Mentor]

VO2 max can decrease as a consequence of overtraining.The other aspect to consider is the accuracy of your measuring device.

Technology can be helpful, but only if you understand how it works, how it can be misleading and what the actual readings signify.

One off readings are not particularly useful but trends over time can be revealing.

[Daiwalker]

I believe the Garmin calculation for VO2 max includes, but is not exclusive to, the types of training (as well as quantity of training as stated in previous posts). The app on the phone (and likely online) drills deeper into what it considers to be 'lacking' regarding the types of workouts. I'm often okay on aerobic but lacking anaerobic activity.

[Hidden]

I have the same, but someone told me that it gives you a general VO2 at the beginning and only after X time of training does it start to come closer and closer to the reality. So you have to ignore the VO2 of the first months or something.

[Jools2020 Graduate]

Pinch of salt, I think. Maybe as Iannoda says, trends can be revealing. Just checked mine and it’s says my fitness age is 36, top 10% of my age and gender. I’m 67. 😂 Previously, it had my fitness age as 31. Then I went on a 10K run!

[nowster Graduate]

I agree with the others. I've done long, slow, aerobic runs, and the blessed watch has rewarded me by downgrading my fitness age by a few years.

I'm 52, and my VO₂Max is currently 42, with a fitness age of 38. The fitness age has been as low as 35 in the past. When I was recovering from an injury and was just restarting with slow, short runs, my fitness age exceeded my real age for a few weeks.

What I have found is that the watch likes you to do short, strenuous exertions, but doesn't like activities which are lower intensity but much longer. I include the figures in my run write-ups more for their amusement factor.

[Tasha99 Graduate]

Far too early to consider VO2 max! It still be calculating your level and it only goes up when you do hard, fast runs which are something to work towards too. Maybe look again in a year.

[swissfish Graduate]

Thanks to everyone who replied - much appreciated. I'll keep an eye on it, hopefully it will begin to go up again!

Have a good 2021 everyone.

John