Note: This post was originally (mostly) written back in February but was a bit of an incoherent mess so it got abandoned in my drafts. Here it is, cleaned up and made a bit less rambly.
I probably shouldn’t even bitch about this at this point, since it’s not like it’s the first time I’ve noticed this, or the first time it’s actually been this dramatic of a fail; after all, it was what kept me from realizing I had POTS for so long. I even had a big go-around with the company after that, whereby I tried to get them to admit their trackers were horribly inaccurate… they just sent me a new one instead, and when I showed that one was inaccurate as well, they offered to send a third without acknowledging any inaccuracy, which was pointless, so I gave up.
For a while there, I was wearing two fitness trackers, the FitBit and the Gear Fit II, because neither one was really accurate, but they were accurate in different ways… and then I decided that just made me look like a big dork and was bordering on obsessive, and when I busted the Gear Fit II also being inaccurate (but showing the heart rate as way higher than it actually was) I put that one away, because that was the only thing (I had thought) it did well. Incidentally, I’ve checked them both by measuring by hand, as well as against my Polar H10 chest strap and a blood pressure cuff, to determine that they are off.
The chest strap, which is vastly more accurate, would be uncomfortable to wear all the time, and takes coin batteries that are a bit hard to change, so I decided that I should just stop obsessing over the issue. I kept the FitBit on, out of habit, I guess, and because I like the step and stair counts (which seem to be spot-on – that’s where the Samsung device was badly inaccurate) and the app. When I started exercising a few weeks back, I wore the chest strap a few times, but the FitBit didn’t seem too far off, so I figured it was close enough for measuring the range the doctor said that I am supposed to stay in for my workouts.
I’ve been feeling really crappy the past week or so, but trying to just power through and hope that I’d eventually feel better. I skipped a few workouts this week because my work schedule didn’t allow for a long enough lunch, so today when I got home I thought I’d do some walking up and down the hill, at least. I’m not even sure why I decided to break out the chest strap for that, but I’m glad I did! Here’s how FitBit thinks the workout went:
Barely able to keep it in that 120-140 range I’m supposed to be in, and not even really a cardio workout at all. Gee, I must really be out of shape because it felt I was really exerting myself big time… or wait, could it be instead that the 110 I read at one point on my wrist tracker was actually 170, which is what the chest strap app was displaying?
Yeah… those three peaks correspond to the three trips uphill, and this is actually way harder than I’m supposed to be pushing it, especially given that I’m on a beta blocker so getting to 174 means I’m really exerting myself. Granted, I’m also in a bad POTS flare, but I would have had no idea just how bad that was affecting my workout ability if I’d just relied on the tracker. Yesterday I reacted to something I ate and my heart felt like it was racing as hard as it was coming up that hill today; I actually wanted to ask a coworker if I could lay on the floor in her office but we were in the middle of a vendor presentation and I didn’t want to disrupt it. I wonder how high my pulse actually was… I’m guessing much faster than the 121 I measured.
The vendors for these fitness trackers point out that they are not medical devices, and I get that, but being this inaccurate makes them a pretty crappy workout tool, too. I really wish there was a wrist based tracker that would maintain an accurate continuous heart rate measurement – maybe with an app that could give an optional alert if it exceeds a certain threshhold.
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