Thanks to watchOS 4.2 apps like Slopes, snoww, Squaw Alpine, Snocru and Ski Tracks can now accurately report metrics like vertical descent, distance, number of runs, average speed and calories burned thanks to the built-in altimeter which can develop elevation.
More importantly, this information is gathered and reported towards a user's fitness performance. Being able to track calorie burn, run count, and speed make use of hardware like the altimeter elevation readings, accelerometer and GPS.
In the same way Apple has tuned the Apple Watch for swimming activity and exercises, the new algorithms areoptimized for snow sports.
The new updates to the third-party apps enable data collection for snow sports, which can be fed back into the user’s HealthKit database. This means users can gain credit towards their Activity rings with new workout records. The apps can also auto-pause just like the system Activity app behavior for outdoor runs.
Source: 9to5Mac