Hello Allan Rubé,
It sounds as though your Apple Watch isn't accurately displaying your heart rate results. To confirm, have you followed the tips in the "For best results" section of the following article? If not, review those tips as they can be helpful in ensuring accurate measurements.
Monitor your heart rate with Apple Watch
If you've followed those tips, restart your Apple Watch using the steps listed below. While restarting is a simple step, they can be very helpful in resolving many issues.
- "If your Apple Watch is charging, take it off the charger.
- Press and hold the side button until you see the power button
in the upper-right corner of the display. - Tap the power button.
- Drag the Power Off slider.
- After your watch turns off, press and hold the side button again until you see the Apple logo."
Restart your Apple Watch
If you continue to have issues after completing those steps, you'll want to reach out to Apple next. You can find their contact details via the link below. This will give Apple the opportunity to look in to this issue further.
Contact - Official Apple Support
Take care!