In my day job, I work in systems engineering and data science for a hospital. But I’m a weird combination of tech-geek and luddite. I don’t like a lot of modern smart-tech because it all thinks it’s smarter than you and knows what you want better than you do. For me, when managed workflow meets user experience, I’m firmly on the user’s side. Make things simpler and less capable, rather than more complicated and “so capable it’s useless” – a state I refer to when, like Apple and Microsoft products these days, the developers have crammed in so much capability that the tool is a bewildering labyrinth of menus and options that never quite do what you want them to.
My Garmin Fenix 5 toes the line. It took me a few months to get used to the menus and options, isolate the ones I wanted to use, and turn the rest off. That’s crucial for me: I have to be able to turn off what I don’t want. So many tech products give you no (or no obvious) way to turn off features that degrade your experience. I identified some fitness measures I liked the way it reported and so I used them. Specifically, VO2max.
Now, there’s no way a watch can actually calculate VO2max. It normally requires wearing a facemask and measuring O2 intake and CO2 output at various levels of exertion on a treadmill. It’s an advanced metric that’s normally only calculated for elite athletes. I am not an elite athlete. No one is interested in measuring my actual VO2max except for me. And I’m not interested in a full work up.
What I am interested in is watching a number change slowly in a way that reflects my subjective experience of my fitness. Last spring and summer, Garmin’s estimate of my VO2max from my active HR and pace was doing just that. I watched as it climbed from 38 to 46 over the course of a few hard training months and was gratified. It reflected how I felt and where I was, culminating in a trail 10K with 800′ of gain at a 10 minute pace. I was strong, fast (for me), and fit.
Then I got injured.
I didn’t run for about 6 or 7 weeks and then I returned slowly. When I did start running again, Garmin was confused. I was supposed to be a 46 but I was running like something much lower. How much lower? I don’t know. Garmin’s algorithm is clearly not designed to track big “sudden” changes. It wasn’t sudden in terms of time, of course, but it was sudden in terms of activities. One activity I was a 46! The next I was – what? – a 40? And my Garmin had a bit of a nervous collapse.
For months, my VO2max measurement was in slow-motion free fall. Even when my performance was objectively improving, my VO2max was collapsing like a shaken souffle. I found it frustrating, because I’d come to appreciate the number as reliably tracking where I physically felt and could perform, and now it wasn’t doing that. As the months went by I found it more and more distracting and then finally very discouraging as my number kept dropping even while I ran trail marathons and ultramarathons.
I finally took some advice this past weekend, and reset my watch to its factory settings. My VO2max number had dropped all the way to 39 – where I am when I’m almost detrained. I knew it wasn’t right. I am not where I was (46) last summer (because I’ve been doing a lot fewer road runs and less speed work, which really jack my VO2max), but I knew that 39 and “completely out of shape” was also garbage.
Lo and behold: the first run after the reset, my VO2max jumped up to 43. That’s much more like how I feel again. I have my suspicions about the technical explanation for the failure. But I’ll spare you all that (it revolves around a systems engineering concept called “integrator windup”.). But I think that now that I’m running consistently with a fresh start to the algorithm it will measure me more accurately again.
And let this be a lesson to not just blindly rely on tech. How I feel is a better indicator of my fitness than the numbers my watch was reporting are. I’m reasonably fit, and in a good position to move forward for my big goals this summer – when my tech was discouraging me. And if you take some time off from running, and you use a Garmin to calculate your VO2max – if that matters to you – reset your watch after your break, or it may become puzzled and unreliable.
Boundary Conditions 