workout pausing

Hi

If it is not already enabled, then be sure to enable Wrist Detection. You might also wish to use these other settings for your Apple Watch:

• On your iPhone, in the Watch app, go to: My Watch (tab) > Passcode > turn on each of Wrist Detection, Passcode and Unlock with iPhone.
• After putting it on your wrist, your Apple Watch will then unlock after whatever you do first: either unlocking your watch manually (by entering the passcode) or unlocking your iPhone. It will then remain unlocked (including when the screen is asleep) until you remove it from your wrist. When you remove your watch, it will lock automatically:

  Turn on, wake, and unlock

The behaviour that you described may otherwise have been caused by your Apple Watch losing contact with your wrist during your workout, causing it to conclude that it had been removed from your wrist.

During exercise, Apple Watch should be worn snugly on the top of your wrist. Apple suggests that you consider tightening your band before workouts and loosening it again afterwards.

• Wearing your Apple Watch - Apple Support
• Your heart rate. What it means, and where on Apple Watch you’ll find it. - Apple Support

Sensor performance can otherwise be affected by temporary or permanent skin changes, such as by some wrist tattoos. The behaviour can also be caused by accidental screen interactions, potentially including caused by clothing.

To avoid accidental interactions with the screen during workouts - which may include pausing workouts or ending them early - the screen can be locked by following the instructions here:

End, pause, or lock

If you have not yet done so, then it may also help to update your iPhone and Apple Watch to the latest software, starting with your iPhone:

• Update your iPhone, iPad, or iPod touch - Apple Support
• Update your Apple Watch - Apple Support