To those of you questioning if the fitness rings on the iPhone app updated at different speeds depending on whether you have the fitness app running on the watch or not I can confirm the following….
I have just competed a 10 minute elliptical exercise wearing 2 identical Apple Sports watches. One on each wrist and straps both tightened to the same fitting. Both watches are running V1.01. During the workout I reached a heart rate of approximately 140 on both watches.
At the end of the 10 minute exercise the following data was noted:
Watch running the elliptical activity app: 85 total calories and 10 minutes of exercise.
Watch not running any workout: 48 total calories and 6 minutes of exercise.
So you can see by doing exactly the same exercise at the same time on the same person you get 2 totally different results depending if you are running the watch’s activity app or not.
Further more, the actual watch activity app itself recorded 93 total calories. So why does that differ from the 85 total calories the SAME watch sends its paired iPhone fitness app? So now we have 3 different calorie burns for the same exercise: 93, 85 and 48!
While I agree I was wearing a friend’s watch as my second testing device, we are of similar build and fitness. Based on our daily resting calorie comparison we burn a difference of 3.5 calories every 10 minutes. In this exercise the difference was 37 calories over 10 minutes. Imagine how inaccurate it would be if I exercised for a couple of hours, then multiply that up into days, weeks and months.
Personally, I think the watch data is fundamentally broken and any data it produces should be taken with a pinch of salt.
I'll copy this post to Apple feedback.