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Apps Fitnes INaccuracy

Pagemakers

Pagemakers

macrumors 68030
Original poster
Mar 28, 2008
2,945
1,223
Manchester UK
I'm wearing a heart band and have just been out for a 30 minute bike ride.

My heart monitor (Polar) app correctly registered the 30 minutes. The watch measured 8 minutes of excercise.

The polar app measures 500 calories. The watch 308 (which is still inconsistent with 8 minutes).

The polar is giving me a heart rate of approximately 92bpm and the watch 58bpm.

The watch was correctly worn.

I've previously worn a Microsoft Band and that is close to the Polar.
 
Did you use the Workout app?

You either using it wrong or your heart sensors are defective since tests have shown that Apple Watch measures your heart rate very precisely.
 
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If you didn't use the workout app then, at most, your heart rate was monitored 3 times during that 30 minutes. If the workout app was running, then it constantly monitors your heart rate in which case something may be wrong if it averaged 58bpm
 
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Were the Watch and Polar strap connected to the iPhone at the same time? That might cause issues... If it's even possible.

If you are lowering your intensity to do a manual measure, the Watch will lag, and your heart rate is not steady, it is decelerating. It's just not how it's supposed to work. Use it alone, tell the Watch you are riding a bike, and have the HRM go the whole time.

How do you know it's worn correctly?

It needs to be tight enough to not move around, but not so tight that it constricts blood flow. It may seem like it's not too tight, but it may be.

Also, some people need to move the band up or down the arm a bit to get a better reading.
 
Which option do I have to use for the weight workout? And for the aerobic/step/yoga..? Thanks.
 
So far I’m not convinced with the Watch’s fitness accuracy.

Just done a cross trainer workout for 30 minutes.

I’m wearing a watch. A Polar heart rate monitor and the cross trainers built in heart rate monitor.

After 30 minutes:

Cross Trainer: 290 Calories
Polar Heart rate Monitor: 304 Calories
Cardiio iPhone Heart Rate App*: 300 Calories
Watch: 144 Calories

My watch is fitting correctly and was correctly recording a heartbeat of approx 130 - the same as the others.


*Note: I recently had a hospital visit and was wired up to a heart rate monitor for about 7 hours. I used the iPhone Cardiio app about 20 times to check the accuracy against the hospital equipment and it was 100% accurate 100% of the time.
 
The watch is only reporting your active calorie burn, not your total calorie burn. Many other apps report the total of your resting and active calories combined - I don't think you are comparing like with like.
 
priscilla55 said:
The watch is only reporting your active calorie burn, not your total calorie burn. Many other apps report the total of your resting and active calories combined - I don't think you are comparing like with like.
Click to expand...

Agreed. I often get "lower" calorie readouts from my Apple Watch than my cross-trainer, but the two become far closer when I look at my total calorie burn on the Apple Watch, rather than just active calories.
 
Yeah, from time to time I will get a heart rate reading of about 90 when I'm just resting in bed, and then when I do a manual reading with the watch in the glances, it will give the right reading of about 60. I dont understand if suddenly my heart just starts racing for no reason or if its something to do with my watch and how tight or not it is?
 
priscilla55 said:
The watch is only reporting your active calorie burn, not your total calorie burn. Many other apps report the total of your resting and active calories combined - I don't think you are comparing like with like.
Click to expand...

Agreed but my resting calorie burn cannot be more than my active burn. That's nonsense. There is a discrepancy of 50%.

Just walked to my post box and back today. It's .57miles. Yesterday it was .51 - I walked exactly the same route. As I was walking I took an occasional glance at my watch (it was on the walking activity). It reckoned my heart rate was 61. 2 minutes later it correctly displays 91. Then a few minutes later 57.

I've checked and checked and the strap is fitting correctly.

I don't think my watch is faulty. I just don't think the fitness stuff is that accurate.
 
Pagemakers said:
Agreed but my resting calorie burn cannot be more than my active burn. That's nonsense. There is a discrepancy of 50%.

Just walked to my post box and back today. It's .57miles. Yesterday it was .51 - I walked exactly the same route. As I was walking I took an occasional glance at my watch (it was on the walking activity). It reckoned my heart rate was 61. 2 minutes later it correctly displays 91. Then a few minutes later 57.

I've checked and checked and the strap is fitting correctly.

I don't think my watch is faulty. I just don't think the fitness stuff is that accurate.
Click to expand...

The machine is lying to you and trying to say the energy you used staying alive counted as calories burned while using the machine. The apple watch is actually more accurate in this circumstance, in my opinion, because it is showing you the extra calories you burned working out vs sitting on the couch.
 
ipaine said:
Agreed. I often get "lower" calorie readouts from my Apple Watch than my cross-trainer, but the two become far closer when I look at my total calorie burn on the Apple Watch, rather than just active calories.
Click to expand...

Don't forget your TOTAL calories burn is just that.

Your total calorie burn at 9am will be very different to your total burn at 5pm even if you just sat on your bum all day, so adding them together will not give you an accurate calorie burn for your treadmill excercise. It will be greater at 5pm than 9am. If you burn 300 calories on your treadmill you burn 300, not 2000 at 5pm or 330 at 9am


DISREGARD MY COMMENTS ABOVE!
 
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Pagemakers said:
Don't forget your TOTAL calories burn is just that.

Your total calorie burn at 9am will be very different to your total burn at 5pm even if you just sat on your bum all day, so adding them together will not give you an accurate calorie burn for your treadmill excercise. It will be greater at 5pm than 9am. If you burn 300 calories on your treadmill you burn 300, not 2000 at 5pm or 330 at 9am
Click to expand...

I think you misunderstood my point. I was not referring to the total calorie burn for my entire day, merely the total calorie burn for each particular workout, which appears once you end the workout.
 
ipaine said:
I think you misunderstood my point. I was not referring to the total calorie burn for my entire day, merely the total calorie burn for each particular workout, which appears once you end the workout.
Click to expand...

Hmm, I think you are right...

I didn't realise that each excercise has both active and resting calories.

It might sound like a stupid question, but why would you have resting calories during say a 20 minute cross training session?
 
Pagemakers said:
Hmm, I think you are right...

I didn't realise that each excercise has both active and resting calories.

It might sound like a stupid question, but why would you have resting calories during say a 20 minute cross training session?
Click to expand...

It's because your metabolism (resting calories) continues to work whilst you're exercising - so at that point in time you are burning your ordinary level of resting calories + your active calories.
 
ipaine said:
It's because your metabolism (resting calories) continues to work whilst you're exercising - so at that point in time you are burning your ordinary level of resting calories + your active calories.
Click to expand...

Thanks for the info. That makes sense.

However, my other 2 devices were saying 290/304 calories. If I take the total calories, it goes from 144 to 191. That still a 30% discrepancy compared to the other two.
 
Pagemakers said:
Thanks for the info. That makes sense.

However, my other 2 devices were saying 290/304 calories. If I take the total calories, it goes from 144 to 191. That still a 30% discrepancy compared to the other two.
Click to expand...

Your Apple Watch will be using an algorithm based on the information you gave it regarding your age, sex, height and weight. Is this information identical on both devices? Any differences are likely to be a reason for the discrepancy.

And do your other two devices have heart-rate monitors? Whether or not they do will also have an impact on your calorie readout.
 
ipaine said:
Your Apple Watch will be using an algorithm based on the information you gave it regarding your age, sex, height and weight. Is this information identical on both devices? Any differences are likely to be a reason for the discrepancy.

And do your other two devices have heart-rate monitors? Whether or not they do will also have an impact on your calorie readout.
Click to expand...

They do have heart rate monitors but they have no idea of my sex, age or size. Good point! Thanks.
 
everyone is saying use the work out app? Does the apply watch do all of this in the background using the activity app? I'm confused?
 
Pagemakers said:
Just back from a bike ride. Heart rate was from 59-120 during the ride.

Impossible!
Click to expand...

Without knowing your normal HR range it is difficult to comment. However... here is an issue I have noticed that may be your problem.

When I do pushups it has issues reading my HR and often reads low (in the 50s usually). It seems that the hand position when riding your bike may be similar (bent) and that we are having the same issue. Why does that matter and how is it affecting the HR reading? From what I read bending your wrist will eventually (pretty quickly I'd imagine) cause the blood to back up (or slow down) and lead to inaccurate readings.

This makes sense to me as I only have an issue when my wrist is bent (seems to function just fine during sprints/longer runs). It doesn't happen instantly but it doesn't take long either. Unfortunately I don't remember where I read this (thought it was in a thread here) but again I only experience this issue when my wrist position is at an angle.

The calorie issue seems to have been adequately explained. I would always think the device with the most metrics (i.e. weight, sex, etc.) would be the most accurate.

Edited to add: Of course your calories will certainly be off if the HR is off due to the problem I described above
 
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