Be Sure to Start a Workout
The watchOS Activity app should automatically track any movement that’s more intense than a “brisk walk,” according to Apple. But the Apple Watch relies on the natural swing of your arm to calculate this. If you’re using your arm for something else, like pushing a stroller or holding a dog leash, you may get inaccurate measurements.
Because of that, we recommend using the Workout app for these instances. Just tap on the Workout app