alt Hacker NewsThis comment confuses me. Why would we expect calorie burn to be related to steps and heart rate? How could a wearable measure energy expenditure? What if someone was wearing a heavy backpack? The energy to move the backpack has to come from somewhere but the wearable can't tell that the person has one.
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Is it really that confusing? Heart rate is correlated with oxygen consumption which is correlated with metabolic activity. The wearable would see the increased heart rate when a person is moving with a heavy backpack versus moving without one.
Now whether we can do that accurately with today’s wearables and without calibration to each individual is up in the air as far as I’m concerned. But it seems strange to me that you’re confused as to how we could even directionally infer these things.
Isn’t that in line with the comment, that they aren’t accurate?
> Why would we expect calorie burn to be related to steps and heart rate? How could a wearable measure energy expenditure?
A lot of exercise equipment manufacturers will display very approximate numbers, based on assumptions the user can adjust if they want (but they seldom do).
If you jump on a treadmill at the gym and set it to a brisk walk, it'll show you a 'calories burned' count that goes up by 7 calories per minute based on your speed and an average adult's weight.
It doesn't have to be all that accurate to motivate the user to just do 5 more minutes, and to put a checkmark on a product feature list.