Apple Watch can pair and sync with compatible gym equipment by following the instructions here:
Use gym equipment with Apple Watch
The following steps may otherwise help:
When recording specific fitness activities, be sure to use the Workout app and to choose the activity type that most closely matches your workout:
Keep in mind that, when estimating results for indoor walks and runs recorded via the Workout app, Apple Watch cannot recognise or adjust for inclines or declines on a treadmill.
When comparing calorie data recorded by different devices and their apps, also keep in mind that Apple Watch reports active energy / calories, whereas many other fitness devices and apps report total energy (resting + active calories).
If you have not yet done so, update your iPhone and Apple Watch to the latest software, starting with your iPhone:
Check your personal information:
- Calorie estimations depend, in part, on your personal information.
- To check that this is accurate - and to update it over time:
- On your iPhone, in the Watch app, go to: My Watch (tab) > Health > Edit - tap and adjust items, then tap on Done.
Check that you are wearing your Apple Watch correctly:
- For the best performance from the heart rate sensor - which is used continually during workouts, with readings used when estimating active calories burned - be sure to wear your Apple Watch snugly (but not too tightly) on the top of your wrist.
- Apple suggests tightening your Apple Watch band before workouts and loosening it again afterwards:
- Sensor performance can be affected by skin changes, such as by some wrist tattoos.
Prior to calibrating your Apple Watch (see the next step), check your Location Services settings:
- On your iPhone, go to: Settings > Privacy > Location Services:
- Check that Location Services (the main setting at the top) is turned on.
- In the list of apps beneath, check that Apple Watch Workout is set to While Using.
- Also enable options under System Services including Motion Calibration & Distance, Wi-Fi Networking and Mobile Network Search.
Calibrate your Apple Watch, resetting any existing calibration data and starting afresh:
Be sure to allow the arm on which you are wearing your Apple Watch to swing naturally during treadmill-based workouts (and also during calibration).
Get the most accurate measurements using your Apple Watch - Apple Support
Use the Activity app on your Apple Watch - Apple Support
Work out with your Apple Watch - Apple Support
Your heart rate. What it means, and where on Apple Watch you’ll find it. - Apple Support