https://thenextweb.com/apple/2018/06/04/apple-announces-watchos-5/

Apple today introduced watchOS5 with new updates including updated algorithms for health and fitness, a walkie-talkie feature, 3rd party app support, and a better way to talk to Siri.

Fitness updates: A new workout type for yoga including heart-rate monitoring and tracking, and another for hiking that helps to measure pace and heart-rate. Can also now set a custom pace alert, and runners will also get cadence so they can see current steps per minute. Watch will also detect when you’ve ended your workout and suggest you stop it if you’ve forgotten.