Hi
When recording a workout via the Workout app, choosing the activity type that most closely matches your workout enables Apple Watch to use the most appropriate sensors and data sources when estimating the results, including using tailored calorie calculations for the main, preset activity types.
For activities that are not included within the list or that are not sufficiently similar - including rollerblading - record your workout under "Other".
This credits one minute of Exercise for each full minute of the workout. Active calories for Other workouts are estimated at a rate equivalent to a brisk walk or based on data recorded by the heart rate sensor, whichever is higher.
Upon ending the workout, tap on the option to Name Workout, which offers a range of activity labels for naming the workout. As you have identified, these labels currently include Skating, but not Rollerblading.
Users cannot create additional naming labels. However, note that, when naming an Other workout, the choice of label has no effect on how results are estimated or presented.
If you would like to submit a feature request to Apple for Rollerblading to added as a main workout activity type or a naming label option, then you can do so here:
Feedback - Apple Watch - Apple
(You are not talking to Apple here - this is a user-based technical support community).
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