The Apple Watch can only run 1 workout app at a time. This is because workout apps require continuous feedback from the watch's sensors for distance, heart rate, etc. The Watch cannot provide this feedback for multiple apps at once. 

 

We've implemented a safeguard notification to make sure you're aware that the Workout Companion stopped recording once you started another workout app on the Watch. 

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We recommend choosing 1 workout app to run on your Watch at a time.