How can i set up running interval training in watch OS4

Hi

Whilst the built-in Workout app includes an HIIT activity type, it is not possible to set a schedule of intervals using the Workout app.

You may find that a third-party app meets your needs. Apps that you may wish to consider include, for example:

Intervals

• "Intervals is the fastest growing interval timer for iPhone, iPad, and Apple Watch."
• "Intervals is an easy to use and modern iOS 10 and watchOS 3 interval timer for HIIT, Tabata, and all interval workouts."
• "You'll love using this carefully crafted app to guide you through any type of interval workout, including running"
  
• Intervals - Workout Interval Timer on the App Store

Runmeter

• "Built from the ground up for iPhone, iPad, Apple Watch and iCloud, it makes your iPhone a powerful fitness computer — with maps, graphs, splits, intervals, laps, announcements, zones, training plans and more."