What is Companion Mode?
The heart rate sensors on Apple Watch normally take measurements every 5-10 minutes. During "workout" mode, these sensors can operate much more frequently in order to provide more accurate and up-to-date heart rate and energy information.
If you're logging a workout in Strong for iPhone and own an Apple Watch, you may have noticed that the heart rate and energy data in the Activity or Health apps isn't as accurate as you'd expect because the sensors on your Apple Watch aren't operating at high frequency. Companion Mode works by activating your Apple Watch to run in "workout" mode whenever you start a workout in Strong for iPhone. It also shows some basic information about the workout on your iPhone, and provides haptic notifications when your rest period is up.
If you've installed and set up Strong for Apple Watch, you can turn on Companion Mode by going to Settings → Apple Watch. Companion Mode will start and end automatically when you start and end a workout on your iPhone.
This is an alternative to manually starting a workout using the Workout app on your Apple Watch. Note: watchOS doesn't support multiple "workout" apps running at the same time, so never use the Workout app at the same time as Strong for Apple Watch.
Companion Mode is unrelated to starting a workout in Strong for Apple Watch, which runs independently of your iPhone, and automatically uses "workout" mode.
We'll be adding more features to Companion Mode once we're confident that the basics are working correctly on all Apple Watch models.