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> When it comes to energy expenditure, Apple is the only fitness tracker providing a strong accuracy of 71.02%. Jawbone, Fitbit, and Polar yield only moderate a

> When it comes to energy expenditure, Apple is the only fitness tracker providing a strong accuracy of 71.02%. Jawbone, Fitbit, and Polar yield only moderate accuracy, ranging between 50.23% and 65.57%. I don't buy it, no brand can be accurate on energy expenditure because it depends on a lot more things than what the watch can monitor. Even in lab they have to put big mask on people while exercising to get something somewhat accurate. On watch, calorie counter is a function of time and heart rate. Yet most watch brand can't even get heart rate right beside apple and Huawei. Tried all the brand, went back to using a 10€ Casio and put a H10 monitor when doing sport.

Moto7451 2y ago
At least in the case of Apple I have met a couple people who work on the fitness products and their accuracy. One of the people does real world testing so they are diving one day and coding the next. Great work if you can get it and your hobbies align. The lab setup you describe is basically what they have to setup to correlate their proxies to energy. I’d expect the variability is going to come as a factor of body efficacy. I used to be in much better shape (resting heart rate in the 50s) but I’m not much heavier and haven’t lost much of the muscle I gained (70ish percent of my former one rep max achievable). My day to day non-workout energy burn is measured higher now than it was when my heart rate was lower for all activity levels. I don’t think that it’s true I’m suddenly +15-20% energy consumption simply because I put on 10lbs but rather having a 10bpm increase in heart rate is probably what is being measured. Short of that though it does a pretty good job. If I’m doing things that are strenuous but my arms are stationary it picks up the work. Very old wrist trackers needed to have an arm pumping or otherwise moving to do anything aside from a pre-calculated “you are alive” burn. Given the level of effort for what we get, I’ll take it as a basic way to answer “did I actually get some exertion from watching my 2 year old today?”
- aucisson_masque 2y ago
  > Given the level of effort for what we get, I’ll take it as a basic way to answer “did I actually get some exertion from watching my 2 year old today?” That's what I initially started using it for but the best finally is just to do exercise everyday. Not everyone has time to run 2 hours or bike during 3 hours, but the bare minimum to stay healthy is 30 min of moderate to high intensity workout, which I think everyone could do. If you stick to that, there isn't even any need to monitor yourself with a smartwatch.
robot_jesus 2y ago
>I don't buy it, no brand can be accurate on energy expenditure because it depends on a lot more things than what the watch can monitor To be fair, the comment you excerpted noted that the best performer was still just 71% accurate. So they’re saying they’re far from perfect. >On watch, calorie counter is a function of time and heart rate. Well, we just don’t know. But let’s take Apple as an example. Apple knows your workout type. And they know your weight if you’ve entered it. And lots of other sensors as well (O2, if possible, temp, accelerometers, etc). They’ve put a crazy amount of money into their testing lab where they do have extensive metabolic rate testers, VO2 Max, etc. Will they get as good as that equipment for a dinky watch? No. But I also am glad I don’t have to strap a face mask on during my daily bike rides. Can they, with insane volumes of data and hard research, make pretty good directional inferences using models that match their watch sensors to gold standard tests? It seems the answer to this (both logically and in the research data) is yes. This video is a decade old so they’ve only become more advanced and have more data since then, but there are lots of models you can build to power these estimates: https://youtu.be/BceaTNT14Ao https://youtu.be/BceaTNT14Ao I’m glad you’re happy with your Casio. Keep rocking what works for you. But I’m not sure what’s so hard to believe here when other researchers have actually produced the data on their accuracy.
kqr 2y ago
> no brand can be accurate on energy expenditure because it depends on a lot more things than what the watch can monitor. I was going to quip that I can probably look at a person and state their energy expenditure with 70 % accuracy (whatever that means -- I'm going to assume coefficient of determination.) Just someone's weight alone ought to have nearly a 70 % r² with energy expenditure. (A quick internet search suggests 71 % though I have not bothered verifying their methodology.[1]) Of course, they could mean 70 % across days for the same person, which is significantly more impressive as it takes out the strongest signals, but it's not at all clear what they actually mean and that's sort of my point. Edit: I read the article closer now and when they say 70 % they actually mean a Pearson r of 0.7, i.e. a coefficient of determination of 50 %. Reporting r as a percentage seems confused at best, or possibly dishonest. [1]: https://www.researchgate.net/figure/The-relation-between-body-weight-and-total-energy-expenditure-or-intake-as-linear_fig2_7178754 https://www.researchgate.net/figure/The-relation-between-bod...
- dmurray 2y ago
  All reasonable fitness trackers use your weight as an input, and there's nothing in the article to suggest the devices weren't provided with this information even though it's not "something the watch can monitor".
  - kqr 2y ago
    That's what I'm saying. If we're discussing an r² of 70 % on a population level they don't need to track anything to achieve that, just use the weight. So before we can say whether 70 % is good or bad we need to know more about what those 70 % actually mean.
mistercow 2y ago
> I don't buy it, no brand can be accurate on energy expenditure because it depends on a lot more things than what the watch can monitor. You could say the same about virtually every modeling problem, yet the world runs on models that work adequately in practice. You measure what you can, infer what you can, and fill in the gaps with priors.
- wlesieutre 2y ago
  As the saying goes: all models are wrong, some are useful
gf000 2y ago
Not adding much to the conversation, but Google Pixel 3 is also quite accurate during running and cycling in terms of HR measurements, according to the already mentioned YouTuber 'Quantified Scientist'.

Moto7451 2y ago

At least in the case of Apple I have met a couple people who work on the fitness products and their accuracy. One of the people does real world testing so they are diving one day and coding the next. Great work if you can get it and your hobbies align. The lab setup you describe is basically what they have to setup to correlate their proxies to energy. I’d expect the variability is going to come as a factor of body efficacy. I used to be in much better shape (resting heart rate in the 50s) but I’m not much heavier and haven’t lost much of the muscle I gained (70ish percent of my former one rep max achievable). My day to day non-workout energy burn is measured higher now than it was when my heart rate was lower for all activity levels. I don’t think that it’s true I’m suddenly +15-20% energy consumption simply because I put on 10lbs but rather having a 10bpm increase in heart rate is probably what is being measured. Short of that though it does a pretty good job. If I’m doing things that are strenuous but my arms are stationary it picks up the work. Very old wrist trackers needed to have an arm pumping or otherwise moving to do anything aside from a pre-calculated “you are alive” burn. Given the level of effort for what we get, I’ll take it as a basic way to answer “did I actually get some exertion from watching my 2 year old today?”

aucisson_masque 2y ago
> Given the level of effort for what we get, I’ll take it as a basic way to answer “did I actually get some exertion from watching my 2 year old today?” That's what I initially started using it for but the best finally is just to do exercise everyday. Not everyone has time to run 2 hours or bike during 3 hours, but the bare minimum to stay healthy is 30 min of moderate to high intensity workout, which I think everyone could do. If you stick to that, there isn't even any need to monitor yourself with a smartwatch.

robot_jesus 2y ago

>I don't buy it, no brand can be accurate on energy expenditure because it depends on a lot more things than what the watch can monitor To be fair, the comment you excerpted noted that the best performer was still just 71% accurate. So they’re saying they’re far from perfect. >On watch, calorie counter is a function of time and heart rate. Well, we just don’t know. But let’s take Apple as an example. Apple knows your workout type. And they know your weight if you’ve entered it. And lots of other sensors as well (O2, if possible, temp, accelerometers, etc). They’ve put a crazy amount of money into their testing lab where they do have extensive metabolic rate testers, VO2 Max, etc. Will they get as good as that equipment for a dinky watch? No. But I also am glad I don’t have to strap a face mask on during my daily bike rides. Can they, with insane volumes of data and hard research, make pretty good directional inferences using models that match their watch sensors to gold standard tests? It seems the answer to this (both logically and in the research data) is yes. This video is a decade old so they’ve only become more advanced and have more data since then, but there are lots of models you can build to power these estimates: https://youtu.be/BceaTNT14Ao https://youtu.be/BceaTNT14Ao I’m glad you’re happy with your Casio. Keep rocking what works for you. But I’m not sure what’s so hard to believe here when other researchers have actually produced the data on their accuracy.

kqr 2y ago

> no brand can be accurate on energy expenditure because it depends on a lot more things than what the watch can monitor. I was going to quip that I can probably look at a person and state their energy expenditure with 70 % accuracy (whatever that means -- I'm going to assume coefficient of determination.) Just someone's weight alone ought to have nearly a 70 % r² with energy expenditure. (A quick internet search suggests 71 % though I have not bothered verifying their methodology.[1]) Of course, they could mean 70 % across days for the same person, which is significantly more impressive as it takes out the strongest signals, but it's not at all clear what they actually mean and that's sort of my point. Edit: I read the article closer now and when they say 70 % they actually mean a Pearson r of 0.7, i.e. a coefficient of determination of 50 %. Reporting r as a percentage seems confused at best, or possibly dishonest. [1]: https://www.researchgate.net/figure/The-relation-between-body-weight-and-total-energy-expenditure-or-intake-as-linear_fig2_7178754 https://www.researchgate.net/figure/The-relation-between-bod...

dmurray 2y ago
All reasonable fitness trackers use your weight as an input, and there's nothing in the article to suggest the devices weren't provided with this information even though it's not "something the watch can monitor".
- kqr 2y ago
  That's what I'm saying. If we're discussing an r² of 70 % on a population level they don't need to track anything to achieve that, just use the weight. So before we can say whether 70 % is good or bad we need to know more about what those 70 % actually mean.

mistercow 2y ago

> I don't buy it, no brand can be accurate on energy expenditure because it depends on a lot more things than what the watch can monitor. You could say the same about virtually every modeling problem, yet the world runs on models that work adequately in practice. You measure what you can, infer what you can, and fill in the gaps with priors.

wlesieutre 2y ago
As the saying goes: all models are wrong, some are useful

gf000 2y ago

Not adding much to the conversation, but Google Pixel 3 is also quite accurate during running and cycling in terms of HR measurements, according to the already mentioned YouTuber 'Quantified Scientist'.