Garmin VO₂ Max, Fitness age, and Intensity minutes

Garmin Venu 2I’ve been noticing for a while that our so-called technological overlords are trying to sell us a vision of meticulously tracked health data that will help us all move toward a fitter, healthier lifestyle—and, hopefully, alert us when things are starting to go awry in these delicate biological machines we inhabit.

Insurance companies are starting to incorporate this data into their decisions on how much to charge you for the pleasure of not losing everything you own should you become ill.

As with all things technological these days, these devices and their data are granted a cachet they’ve done absolutely nothing to deserve. Long story short, take all of these numbers with a grain of salt 🧂 and don’t base your ego or mood 😑 on them.

And let’s hope that either the devices get a lot better or that our societies and/or corporate overlords come to their senses and stop making financially consequential decisions based on them.

We will, of course, have to hope for the former because the latter ain’t gonna happen.

Heart rate & intensity minutes

This figure doesn’t have any real meaning. It’s supposed to be an indicator of how hard your body is exercising. It tracks both “regular” and “vigorous” minutes. You get double the intensity minutes for vigorous activity. It is a mystery how these minutes are calculated. You would think they would be related to heart rate—after all, it’s pretty much the only thing that a Garmin Venu 2 can measure—-but the story is not that simple.

If you’re not tracking an activity, the watch doesn’t seem to measure heart rate very consistently at all. When I ride the indoor bike, it’s not enough to track the activity on my phone, connected via BlueTooth to the trainer. In order to track heart rate and record intensity minutes, I have to start the activity on my watch—otherwise it doesn’t notice that I’m pushing an average of 230W for an hour.

It. just. doesn’t. notice.

How is this possible when the watch is on my wrist, measuring my heart rate? Why doesn’t it notice that my heart rate is considerably elevated? It is a mystery, but it does not. I’ll be 20 minutes into the workout and realize that I’ve forgotten to let my watch know that I’m working out. I look at my heart rate there: 72bpm. Impossible. I sit up, but continue pedaling. I start an activity on my watch. My heart rate jumps to 142bpm immediately. It continues to climb over the next few minutes, settling in between 155 and 170, as I would expect for going pretty much all-out.

But…how is it possible that the watch didn’t notice my elevated heart rate on its own? Why would it just tell me I had a 72bpm? What the hell did it think it was measuring that it suddenly started measuring differently when I told it to pay attention?

Another anecdote.

I went for a walk today, climbing 290m over 4km to a lovely little restaurant called Rosinli that perches on a hill just outside my back door. They’re under new management and seem to be doing a nice job of it, but that’s neither here nor there.

I thought I’d started tracking the hike, but I had, alas, not. This is another point of contention: why does the watch require that I not only select to start an activity, select the activity, and then force me to press again to start the activity? Shouldn’t that be the default behavior? Couldn’t I just press stop if I’d intended only to set up the activity for recording but not really get going yet?

But I digress.

Anyway, I wasn’t tracking the activity and I was so taken with the walk that I didn’t notice that my watch wasn’t alerting me as the kilometers unrolled, as it would had it been tracking an activity. I had glanced at my watch a few times to see my heart rate when my partner asked me what mine was on the steep bits. I saw a maximum of 117bpm and 110 and 111 a few other times. It’s pretty steep back there.

When we got near the top, I finally noticed that I’d forgotten to start the activity. My watch had recorded 0 intensity minutes. It simply doesn’t pick up, on its own, that something is going on. If you’re not within the context of an actively recording activity, then you can’t trust any of the numbers.

I noticed as well that the intensity minutes recorded by my Venu 2 are only about 1/3 of the minutes recorded by the ForeRunner 235 I had for years before this watch.

None of this makes any sense. It feels wildly unscientific and unreliable.

👎 Intensity minutes will only ever be approximate.

VO₂ Max

Similarly, the VO2-max score is nearly useless. For one, it is nearly impossible to see this value. You can dig through the app on your phone to find it—More ➡ Performance Stats ➡ VO2 Max—but you’ll ever see it very fleetingly on your watch. I’ve only ever seen it after a walk, never after a hike. I think it also appeared after a couple of runs, but I don’t run a lot.

It has never once appeared after cycling because… why? Isn’t cycling an endurance activity for which VO₂ Max (A) could be measured and (B) would be relevant, if not important? If I’ve only cycled for a while, then Garmin kind of forgets about my VO₂ Max as if there were simply no way to know that figure until I would just do some exercise.

The value appears on the watch only for a few seconds immediately after having recorded an activity—and then never again. There is no way to view this value on your watch, otherwise.

Anyway, six months ago, after having had my watch for a good month already, my watch was convinced that my VO₂ Max was about 30. This is a terrible score, even for a 70-year-old man. If you’re 70 and only clocking a 30 VO₂ Max, then you should probably see a doctor or take a COVID test, at the very least. You’re not absorbing a lot of oxygen, bub.

This was, of course, right in the middle of a typically spectacular, long-distance, biking season for me. But the needle didn’t move at all until it started to rise all the way to 35 about three months later. Then, over the next two months, it’s risen to 45 and stayed there for a couple of weeks now.

My app now trumpets that I’m in the top 15% of all athletes my age.

Cool, but what am I to believe? What the hell is it actually measuring? And why was it so wrong for so long and now I’m supposed to assume it’s right? And why did it make “jumps” in the span of a couple of weeks a couple of times now? It’s like it just woke up and realized that I exercise.

I mean, it was definitely wrong before. I would have trouble getting up the stairs with a VO₂ Max of 30, so that couldn’t have been right. But why would I now believe that 45 is correct? I have no reason for doing so.

👎 VO₂ Max will only ever be approximate.

Fitness Age

You can probably imagine what I think of this value. I’ve only recently learned about it. You can only find it on the app—More ➡ Health Stats ➡ Fitness Age—but not on the watch.

I honestly don’t even want to hazard a guess as to how this is calculated. I shudder to think of its accuracy.

For the first seven months that I owned the watch, I’d never heard of it, then it suddenly told me sometime last week that my fitness age had decreased to 43. Just out of the blue, I got a message on my watch. Congratulations!

I have no idea what to make of this. Again, I’m in the slowest part of my fitness year. It’s winter and it’s even been particularly slow because the weather hasn’t been conducive to hiking or skiing and I’ve been nursing a sore achilles tendon back to health. I had the watch when I was banging out 200km per week on the bike last summer. Apparently, that level of endurance training didn’t have any effect on my fitness age.

Or maybe it was a software upgrade. Or, maybe…

👎 Fitness Age will only ever be approximate.