Active Calories - Similar Workouts Very Different

[Buadhai]

Today I cycled on a mostly-flat route for a distance of 34.69 km. My average speed was 16.6 km/h and my average heart rate was 102 bpm. Total time was 2:03. My AW 6 called this 389 Active Calories.

Last week I cycled a different flat route for a distance of 34.86. Average speed was 18.1 km/h and average heart rate was 110 bpm. Total time was 1:55. Active Calories were 647.

I can certainly accept the fact that a slightly slower pace and heart rate would burn fewer calories. But here we’re seeing a difference of 67%.

Same watch band at the same level of tightness.

How is this possible?
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[sdz]

Did you tell Apple your personal data (age, gender, height, weight?)

 

[Buadhai]

Did you tell Apple your personal data (age, gender, height, weight?)

Yes, it's all there.

 

[sdz]

You can't compare those two workouts.

1) Too many gaps of HR (~1 hour of HR is missing in the second screenshot)
2) First screenshot HR is 10% higher on average (110vs102) and peaked at 145
3) The HR is more complete in the first workout and it seems overall more strenuous.
4) Elevation is odd in the second one. Maybe due to faulty barometer / GPS reading ?


Check again with complete HR.

 

[Seabreeeze]

Today I cycled on a mostly-flat route for a distance of 34.69 km. My average speed was 16.6 km/h and my average heart rate was 102 bpm. Total time was 2:03. My AW 6 called this 389 Active Calories.

Last week I cycled a different flat route for a distance of 34.86. Average speed was 18.1 km/h and average heart rate was 110 bpm. Total time was 1:55. Active Calories were 647.

I can certainly accept the fact that a slightly slower pace and heart rate would burn fewer calories. But here we’re seeing a difference of 67%.

Same watch band at the same level of tightness.

How is this possible?
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.
?View attachment 1703417
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View attachment 1703418

I get the same type of results, in a way I can replicate. If I carry my iPhone I get about 30% less calories than if I leave the iphone at home. Any chance that might be part of your situation?

 

[andyw715]

I get fairly consistent calorie readings just wearing the watch. A typical 30-33 min walk at 16 min/mile pace. Between 375-400 active cal.

I don't get HR gaps so I would think that is the issue. As my weight has decreased and cardio health has gotten better this past year (lower HR at the same pace, lower weight) the active cal starts to decline.

Sometimes I have my phone, sometimes not. But I don't have the phone contribute its data.

 

[Buadhai]

You can't compare those two workouts.

1) Too many gaps of HR (~1 hour of HR is missing in the second screenshot)
2) First screenshot HR is 10% higher on average (110vs102) and peaked at 145
3) The HR is more complete in the first workout and it seems overall more strenuous.
4) Elevation is odd in the second one. Maybe due to faulty barometer / GPS reading ?


Check again with complete HR.

1) The gaps in heart rate are when I paused the workout for meal and coffee breaks and to take photos. The heart rate is consistently measured when I was actually pedaling.
2) The difference in heart rate is about 8%. The difference in Active Calories is 67%.
3) The heart rate readings are consistent and complete in both workouts.
4) Both routes are relatively flat. The second one is at the beach which may account for the negative elevation.

I agree that it's difficult to compare these workouts, but the Active Calorie difference is too great (67%) to ignore.

Seabreeeze - I always have my phone with me, so that can't account for the difference.

Both my wife and I have independently come to the conclusion that something has changed in the way Active Calories are computed. My wife says that since she got her Apple Watch 6 (Christmas) it takes her much longer to complete her move goal. She used to complete it around mid-day, but now she doesn't complete it until late afternoon or early evening. For me the difference in the Active Calories that I "earn" is so great that I have reduced my goal from 600 to 550. (Give me a break, I'm 71 years old.)

Neither one of us has changed our regular workout routine or daily activities.

 

[Seabreeeze]

First, relative to your observation that something has changed in the way Active Calories are computed, I have been informed by Apple that the newest releases of phone and watch operating systems have solved the problem I have been pursuing. I don't think they have, but I would not be surprised if a calorie algorithm changed.

I have an experiment for you to try. I am also in the seasoned citizen category so my workouts are limited to outdoor walks in the nearby hills. Try taking the same walk twice, preferably with a moderate exertion - more than just a no-elevation-gain walk - once with your phone and once without. Compare the workout reports in the Fitness app on your phone. I suspect you will find that active calories reported for the two walks will differ materially.

Maybe if you are interested we can discuss here after you try the experiment.

 

[Buadhai]

I will try doing my usual cycling workout tomorrow without my phone.

But, I can understand why there would be a difference. As I understand it, if you have your phone with you, the watch hands off the GPS work to the phone; mainly to save watch battery. Different devices; different results.

I'll report back tomorrow.

My morning cycling workout is about 11.3 kilometers. My Active Calories are usually from 215 to 225.

 

[Seabreeeze]

I'm looking forward to hearing from you again. I have a guess at what your active calories will be. I wish I could write it on a piece of paper and not reveal it to you until you see the workout report results. I won't be surprised if the first digit is not a 2.

If you find a material difference between two workout report results I will have one more issue to add to the discussion. But in fear of convincing you I am a bit obsessed with this, I will wait.

Meanwhile, I just looked at your profile. You are isolated in "the Bakersfield of Thailand!" I am laughing at that!

 

[Buadhai]

Background: I know no one will bother to read this, but I think it will do me some good to write it all down.

My wife and I share Activity data. When one of us closes all three rings or wins an award, the other is notified. This is kind of fun and certainly helps with motivation.

Sometime in December my wife started teasing me because I was closing my rings much later in the day than usual. I hadn't really noticed, but after the teasing began I started to pay more attention. Prior to December, the last ring I'd close every day was the Stand ring. I get up about 4:30 AM so usually close the Stand ring shortly after 3:00 in the afternoon. Before December I'd close my Move ring soon after mid-day. But now it's taking me until long after I close my Stand ring and sometimes not until the evening. In fact, on some days I had to add an extra workout late in the afternoon just to close my Move ring. (I just got back from such a supplemental cycling workout.)

I started reviewing recent workouts to see if I could determine when the change in Active Calorie calculation took place. Hence this post. (See the OP.)

A week or so ago my wife complained to me that it was taking her a lot longer to close her Move ring. She blamed it on her new Apple Watch 6. She said that with her Watch 3 she would close her Move ring shortly after noon (she walks from her office to lunch). But now she wasn't closing the Move ring until late in the afternoon.

Granted, this is just anecdotal evidence. On the other hand, I'm a creature of habit. My workout routine hasn't changed in several years. (Because of spine and hamstring problems I had to give up running about five years ago and took up cycling instead.) I do an 11K+ cycling workout in the morning followed by 15 minutes of strength training. I don't have a car, so cycle everywhere I go during the weekdays.

I realize that in the larger scheme of things, none of this is important. On the other hand, the Apple Watch is all about motivation. It's hard to stay motivated when what was once an adequate workout routine is suddenly not quite enough.

 

[webbga]

Background: I know no one will bother to read this, but I think it will do me some good to write it all down.

My wife and I share Activity data. When one of us closes all three rings or wins an award, the other is notified. This is kind of fun and certainly helps with motivation.

Sometime in December my wife started teasing me because I was closing my rings much later in the day than usual. I hadn't really noticed, but after the teasing began I started to pay more attention. Prior to December, the last ring I'd close every day was the Stand ring. I get up about 4:30 AM so usually close the Stand ring shortly after 3:00 in the afternoon. Before December I'd close my Move ring soon after mid-day. But now it's taking me until long after I close my Stand ring and sometimes not until the evening. In fact, on some days I had to add an extra workout late in the afternoon just to close my Move ring. (I just got back from such a supplemental cycling workout.)

I started reviewing recent workouts to see if I could determine when the change in Active Calorie calculation took place. Hence this post. (See the OP.)

A week or so ago my wife complained to me that it was taking her a lot longer to close her Move ring. She blamed it on her new Apple Watch 6. She said that with her Watch 3 she would close her Move ring shortly after noon (she walks from her office to lunch). But now she wasn't closing the Move ring until late in the afternoon.

Granted, this is just anecdotal evidence. On the other hand, I'm a creature of habit. My workout routine hasn't changed in several years. (Because of spine and hamstring problems I had to give up running about five years ago and took up cycling instead.) I do an 11K+ cycling workout in the morning followed by 15 minutes of strength training. I don't have a car, so cycle everywhere I go during the weekdays.

I realize that in the larger scheme of things, none of this is important. On the other hand, the Apple Watch is all about motivation. It's hard to stay motivated when what was once an adequate workout routine is suddenly not quite enough.

I struggle with this same issue. My Apple Watch series 1 became erratic after a few years and my morning workout (70 minutes on the treadmill) began showing differences in calorie burn that were too wide to ignore. I purchased an Apple Watch 5 and things were much better for months and then I experienced another drop. this time I reset the calibration of the Apple Watch and took a walk that afternoon to give it a new base to start from. This worked and my totals returned pretty much to the same level they were. From time to time I vary 30 calories or so, but that does not concern me too much as long as I am getting my workout in. Like you, I want to know that the watch is recording and reporting on a consistent basis,

 

[Buadhai]

I did a calibration walk on my Series 6 soon after I got it last November. I have to go to the bank tomorrow. I’ll walk instead of cycle to redo the calibration.

My wife calibrated soon after she got her Series 6 on Christmas. But she does a 1 or 2 K walk every morning before her run, so calibration should not be an issue with her watch.

 

[Seabreeeze]

I did a calibration walk on my Series 6 soon after I got it last November. I have to go to the bank tomorrow. I’ll walk instead of cycle to redo the calibration.

My wife calibrated soon after she got her Series 6 on Christmas. But she does a 1 or 2 K walk every morning before her run, so calibration should not be an issue with her watch.

I hope you will try the experiment to see your results when you are not carrying your watch

 

[ftaok]

But, I can understand why there would be a difference. As I understand it, if you have your phone with you, the watch hands off the GPS work to the phone; mainly to save watch battery. Different devices; different results.

I don't think it works like that anymore, at least with Apple's stock workout app. I used the stock app on a run a couple of weeks ago and the GPS information that shows up in HealtFit indicated that the AW's GPS was used, even though I had my iPhone with me.

Question. Did you update the wOS on your watch in between those two activities? In the past, every time I updated my watch, the algorithm for calculating calories seemed to change. I'm wondering if this happed to you.

 

[Buadhai]

I don't think it works like that anymore, at least with Apple's stock workout app. I used the stock app on a run a couple of weeks ago and the GPS information that shows up in HealtFit indicated that the AW's GPS was used, even though I had my iPhone with me.

Question. Did you update the wOS on your watch in between those two activities? In the past, every time I updated my watch, the algorithm for calculating calories seemed to change. I'm wondering if this happed to you.

You're right about the GPS. In Health Fit my phone is shown as the source until I got the Watch 6 when it changed to the Watch.

WatchOS 7.2 was released December 14th. I'm sure I updated shortly after that. That would correspond with the change in Active Calories that I experienced.

I will do my usual cycling workout this morning without my iPhone. Stay tuned.

 

[Buadhai]

As promised, I did today's cycling workout with only my watch, leaving my iPhone home:

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As you can see, I was a bit faster today which, I suppose, accounts for the 22 additional Active Calories.

(The difference in total elapsed time is because yesterday I paused the workout but didn't hit the "Stop" button until later. The Total Time is correct.)