How do I measure my heart rate?
1) Swipe left on the watch face to open heart rate, and tap on the Measure button at the bottom of the page to begin measuring your heart rate. During measurement, it's required to properly wear the watch and keep the back of the watch fairly close to your skin until the watch can measure a stable heart rate.
2) If you want to turn on the all-day measurement function, open the Amazfit app and go to "Profile – Amazfit T-Rex – Heart Rate Detection—Detection methiod" and choose to turn on the automatic heart rate detection function.
Notes: With the all-day measurement function on, the watch will regularly measure your heart rate. Swiping up twice on the watch face will display the last measured heart rate value. You can then tap it to enter the all-day heart rate details.