Why is my VO2 Max going down every run? Anyone else had this happen?

Apple Products Apple Watch
1

I’ve been tracking my runs with my watch since September 2023. After about six months, it stabilized at around 59 and stayed there for nearly five more months. Then I quit smoking, and in two months, it climbed to 62.1. But for the last three months, every single run makes it drop, even though I’m getting faster, my heart rate is lower, and my performance seems better.

The only things that have changed are that I’ve gained 5-6 kg, I’m running half the distance I used to, and for about a month, I’ve had a burning feeling in my lungs (thought it was just the cold weather).

Has anyone else gone through this? Should I be worried about my health?

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2

A VO2 Max of 61.2 is insanely high, like pro-level. Unless you’re a professional athlete, your watch might have been overestimating it. Now it could be adjusting to a more accurate number.

Not 100% sure, but just my guess.

3

@Marlow
That’s what I thought too, but why would it stay so steady for months before dropping? I’m not a pro athlete, just someone who runs 10K daily (or every other day), lifts weights, cycles to commute, and stays active overall. But maybe you’re right.

4

@Dev
Just a heads-up—your VO2 Max estimate only comes from your runs. Cycling doesn’t count, and Apple only factors in outdoor runs, walks, and hikes.

5

Talon said:
@Dev
Just a heads-up—your VO2 Max estimate only comes from your runs. Cycling doesn’t count, and Apple only factors in outdoor runs, walks, and hikes.

Yeah, I know. Just mentioning the cycling for overall fitness context.

6

@Dev
The real question is—how do you actually feel? If you’re feeling fine, I wouldn’t stress too much about what the watch says.

7

Marlow said:
@Dev
The real question is—how do you actually feel? If you’re feeling fine, I wouldn’t stress too much about what the watch says.

I feel fine overall, but my lungs burn from time to time.

8

@Marlow
61.2 isn’t elite runner status. Real pros are up in the 70+ range.

I’m 50, an average runner, and had a lab-tested VO2 Max of 57. My watch also gives me a similar number.

9

Ashby said:
@Marlow
61.2 isn’t elite runner status. Real pros are up in the 70+ range.

I’m 50, an average runner, and had a lab-tested VO2 Max of 57. My watch also gives me a similar number.

Appreciate the correction!

10

@Marlow
Here’s a list of real VO2 Max records if you’re curious: https://www.topendsports.com/testing/records/vo2max.htm

Not saying 60 is bad—it’s actually great. But compared to elite athletes, it’s a different ballpark.

11

Your shorter, less intense runs could be affecting your VO2 Max readings.

I did five months of strictly zone 2 running—five miles a day, five days a week, at around 134 bpm. Even though I got faster while keeping my HR steady, my VO2 Max steadily declined.

When I started adding one or two high-intensity runs a week, it went back up.

12

@Paxton
That makes sense, but my runs have actually been getting faster and more intense while my heart rate stays about the same.

13

Dev said:
@Paxton
That makes sense, but my runs have actually been getting faster and more intense while my heart rate stays about the same.

That’s the thing—if your HR isn’t climbing much, the watch might not be registering your runs as ‘more intense.’ It could see your progress as having plateaued.

And if your runs are shorter now, that might be another factor. The algorithm probably weighs duration heavily.