How to use ECG and check blood oxygen levels on Apple Watch

The Apple Watch is one of the most feature-rich smartwatches you can buy, especially models like the Apple Watch Ultra. It can track and monitor all the most important stats, from your daily activity and calorie burn to ongoing heart rate, sleep, and more. There’s one additional useful feature when it comes to heart health that you can get with the Apple Watch: you can take an ECG (electrocardiogram) test to check for irregularities in your heart rhythm, otherwise known as atrial fibrillation (Afib).

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The ECG feature works for users over the age of 22 by using the electrical pulses from your wrist to determine if both upper and lower chambers of the heart are working in rhythm.

Meanwhile, the Apple Watch, one of the best smartwatches you can buy, can also provide details about blood oxygen, which is how efficiently oxygen is carried through your red blood cells from your lungs. Also referred to as Sp02, a blood oxygen reading can help you detect respiratory or lung conditions as well as conditions like sleep apnea.

It’s easy to run both tests and/or check both these stats on an Apple Watch. Here’s how to do it.

How to use ECG on Apple Watch

1. First, make sure that both your iPhone and Apple Watch are running the latest versions of their respective software. Go to Settings, General, Software Update on iPhone.

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2. Go to My Watch, General, Software Update in the Apple Watch app.

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3. Now, go to the Health app on your iPhone.
4. If you don’t instantly receive a prompt to set up the ECG app, go to Browse, Heart, Electrocardiograms (ECG), and Set Up ECG App.

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5. Once set up, go to your Apple Watch and scroll through the text menu (or, if you have it set up as a Grid, find the app) and select the ECG app.
6. A notification will pop up advising about New Classifications that can check for Afib.
7. Read, scroll down, and select Done.
8. You’ll receive a notice reminding you to ensure the Apple Watch is fitted snugly on the wrist you indicated it was on in Settings. If you switched to the opposite wrist, go to Update Settings before taking an ECG to get the most accurate measurement. If it’s correct, select OK.
9. You’ll see the image of a floating heart appear and will be prompted to hold your finger on the Crown. This will most commonly be at the top, right side of the Watch (or, for some lefties like me, you might prefer it at the bottom, left side).
10. Hold your finger on the Crown as instructed for the 30-second period.
11. After 30 seconds of holding your finger still, you will see a reading of your Sinus Rhythm and it will advise if there were signs of Afib detected or not. If so, you should always consult with your doctor or other medical professional.
12. Scroll down and Add Symptoms if desired to save them to notes (like a cold, headache, fever, chills, lethargy, etc.) and select Done.
13. If you get an Inconclusive result, you can wait and take the test again.

What results you can get when taking an ECG from Apple Watch

There are five results you can get when taking an ECG from Apple Watch.

Sinus rhythm – This confirms that your heart is beating consistently at anywhere from 50 to 100 beats per minute (bpm).

Atrial fibrillation – If you get this result, it means your heart is beating in an irregular pattern and you should speak with your doctor.

Low or high heart rate – A low heart rate is considered one under 50 bpm, which could be caused by some medications or if you are training to be an elite athlete. Conversely, a high heart rate could be related to exercise, stress, nervousness, alcohol, dehydration, infection, Afib, or other causes of arrhythmia.

Inconclusive – This result means the test was not able to determine your ECG, which could be the result of a pacemaker, signs of a heart condition the app cannot recognize, or even a physiological condition that prevents a signal from producing a good recording. Your best bet is to wait an hour or so and try again.

Poor recording – It is possible to get a reading that says poor recording. To help prevent this, make sure to rest your arm on a table or other flat surface while taking the reading. Relax and don’t move too much for the duration of the 30 seconds. Make sure your wrist is clean and dry and that the Apple Watch is on the proper wrist, as noted in Settings. Find a quiet place away from other electronics that are plugged in to avoid electrical interference as well.

How to check blood oxygen on Apple Watch

The Blood Oxygen app for Apple Watch measures your blood oxygen level throughout the day as long as you have background measurements turned on. But if you want to take an on-demand measurement, you can do so manually at any time.

1. Open the Blood Oxygen app on Apple Watch.
2. With your arm on a table, your lap, or other flat surface, position the Watch display facing up. You’ll see various tips for taking a good measurement on screen. Tap Next until these are finished.
3. Tap Start.
4. A timer will count down from 15 seconds. Keep still the entire time.
5. You’ll then see your blood oxygen in the form of a percentage. A healthy blood oxygen level should be between 95 and 100%, though there are people who manage with levels below 95%. Consult with your doctor to learn more. Tap Done.
6. Once the measurement is taken, you can also call it up in the historical data captured in the Health app. There, you can also see data the Apple Watch has taken periodically through the day.

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You can measure your heart rate on an iPhone without a smartwatch, interestingly by using the Google Fit app. But being able to take an ECG on demand, along with getting 24/7 heart rate readings, is a great tool for someone with heart conditions, but it’s useful for just about anyone to keep on top of their heart health. While the ECG feature of the smartwatch is not a medical one and should not be used to diagnose, it might detect potential issues, prompting you to book a visit with your doctor to discuss. Being able to show historical readings in the app is also useful for a medical professional to determine if anything seems amiss.

The same goes for blood oxygen, which can help you detect conditions like sleep apnea, potential heart or respiratory conditions, or even see how narcotics, blood pressure, coughing, and more can impact your blood oxygen level.

Together, ECG and blood oxygen readings are just two more useful features you’ll find in Apple Watch that help paint a more holistic picture of your health and wellness.