Wearing your Apple Watch

For best results, the back of your Apple Watch needs skin contact for features like Wrist Detect, the Taptic Engine, and the electrical and optical heart sensors. Wearing your Apple Watch with the right fit — not too tight, not too loose, and with room for your skin to breathe — keeps you comfortable and lets the sensors do their jobs.

You might want to tighten your Apple Watch band for workouts, then loosen it a bit when you’re finished. In addition, the sensors will work only if you wear your Apple Watch on the top of your wrist.

Learn more about getting the best results when you use the Blood Oxygen app.