When I use a Concept2 indoor rower, I also start a Workout on my Apple Watch. Both devices have a heart rate monitor, and both are measuring my calories. Yet there is a wide difference between the two, and I wonder why it is so large. (I understand that Apple Watch's measurement is a rough approximation, but is there more to it?)
Here are three workouts I did today:
Workout Rower Watch % diff 20 min steady / HIIT 259 cal 144 cal active / 173 cal total 80% /50% 35 min HIIT 448 cal 267 cal active / 320 cal total 68% / 40% 10 min low intensity 111 cal 65 cal active / 80 cal total 71% / 39%
My thinking is that the rower is the ultimate authority on calories -- it is an ergometer, designed to accurately measure work, which means energy, which means calories.
So, is the Apple Watch simply wildly inaccurate, or are the two devices measuring different things under the umbrella of calories?