The recent article about Apple changing health data processing algorithms reminded me of an oddity in the Health app data presentation I've been wondering if anybody else has seen. It's not important, and it's just random numbers Apple has an algorithm to guess, but I'm still curious about a trend.
When I look at the last year and a half of Cardio Fitness data, there is a very clear trend: Starts out in the middle of the "below average" band, curves smoothly up to right about the average line over six months corresponding to me exercising more regularly, and then curves back down over six months until it hits the bottom of the "below average" band then more or less stays there.
Here's the most relevant part (the steep drop to the left is noise because I wasn't regularly wearing my Apple Watch prior to that, and after this it bounces around between 30 and 33):
I would have assumed from this that I was exercising more in the first half of 2020 and getting in better shape (which is accurate), and then started slacking off and got really out of shape... which is not accurate. It's not smoothing, when I zoom in the day-to-day estimate is surprisingly consistent over short periods.
My exercise consists entirely of 2-5 mile walks/short hikes in the hilly forest near my house. The routes vary a bit, but are generally pretty consistent, and according to every other metric I was exercising the same amount between April and October 2020, slacked off for a month, then exercised about twice as much throughout 2021. Distance walked, calories burned, minutes walked, flight-of-stair-equivalents climbed, all the metrics agree. And that also agrees with my perception of how much I was exercising.
Likewise, every heart metric other than the estimated VO2max is pretty much flat--heart rate range looks identical throughout, resting heart rate is more or less flat, heart rate variability is very flat, walking heart rate average bounces around within a 10bpm range. I also haven't gained or lost a significant amount of weight.
It's of course possible that there's something seriously wrong with my lungs. It's also possible that this data is complete junk and just happens to look like a trend.
But I'm assuming that something I'm doing is confusing the algorithm that calculates VO2max. Maybe because I am gradually walking slightly faster or picking trails with steeper and longer hills it thinks I'm working harder than before.
I had wondered, previously, if maybe there hadn't been an algorithm change in the way VO2max is calculated, but that recent article implied that old scientific data gets processed through new algorithms, so I'd assume that the consumer-facing data is treated similarly.
Anyway... anybody else seen weird VO2max behavior like this? Any guesses as to what might be going on here?
When I look at the last year and a half of Cardio Fitness data, there is a very clear trend: Starts out in the middle of the "below average" band, curves smoothly up to right about the average line over six months corresponding to me exercising more regularly, and then curves back down over six months until it hits the bottom of the "below average" band then more or less stays there.
Here's the most relevant part (the steep drop to the left is noise because I wasn't regularly wearing my Apple Watch prior to that, and after this it bounces around between 30 and 33):
I would have assumed from this that I was exercising more in the first half of 2020 and getting in better shape (which is accurate), and then started slacking off and got really out of shape... which is not accurate. It's not smoothing, when I zoom in the day-to-day estimate is surprisingly consistent over short periods.
My exercise consists entirely of 2-5 mile walks/short hikes in the hilly forest near my house. The routes vary a bit, but are generally pretty consistent, and according to every other metric I was exercising the same amount between April and October 2020, slacked off for a month, then exercised about twice as much throughout 2021. Distance walked, calories burned, minutes walked, flight-of-stair-equivalents climbed, all the metrics agree. And that also agrees with my perception of how much I was exercising.
Likewise, every heart metric other than the estimated VO2max is pretty much flat--heart rate range looks identical throughout, resting heart rate is more or less flat, heart rate variability is very flat, walking heart rate average bounces around within a 10bpm range. I also haven't gained or lost a significant amount of weight.
It's of course possible that there's something seriously wrong with my lungs. It's also possible that this data is complete junk and just happens to look like a trend.
But I'm assuming that something I'm doing is confusing the algorithm that calculates VO2max. Maybe because I am gradually walking slightly faster or picking trails with steeper and longer hills it thinks I'm working harder than before.
I had wondered, previously, if maybe there hadn't been an algorithm change in the way VO2max is calculated, but that recent article implied that old scientific data gets processed through new algorithms, so I'd assume that the consumer-facing data is treated similarly.
Anyway... anybody else seen weird VO2max behavior like this? Any guesses as to what might be going on here?