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• The Apple Watch provides useful health data like blood oxygen saturation and VO2 max readings.
• It’s also a great tool for tracking medications, logging heart rate data, and tracking Afib history.
• Some doctors even advise patients to invest in one because of its health tracking and accuracy.

The Apple Watch is one of the most full-featured smartwatches you can wear. It counts steps and burned calories, records sleep patterns and tracks monthly cycles but there are plenty of other health features from this powerful device you may not know about.

For example, it offers apps that analyze heart rate patterns and electrical signals (ECG) for any abnormalities. It can also track your blood oxygen levels, which can signal breathing or circulation issues if they’re too low.

Some doctors even recommend certain patients invest in an Apple Watch, like Dr. Aseem Desai, a cardiologist with Providence Mission Hospital, who has his patients use the wearable to monitor heart murmurs or atrial fibrillation. 

It won’t supplant the role of a doctor but it can provide valuable information pertaining to what it tracks. 

Below are eight of the best Apple Watch health features, as well as tips on how they work and why health professionals like Desai have begun relying on patients to use them.

1. Accurate heart rate monitoring 

The heart rate monitor built into the Apple Watch is one of the most accurate you’ll find in any fitness tracker or smartwatch. 

It manages this via built-in photodiodes (light sensing photo sensors) which detect a series of flashing green LED lights. By flashing those lights hundreds of times per second on a wearer’s wrist, the watch can track the flow of blood through your arteries. This allows it to chart how many times the heart beats per minute (i.e. your heart rate).

Although the Apple Watch’s heart rate monitor shouldn’t be considered medical grade, it is more accurate than similar fitness trackers with wrist-based tracking. When tested against an EKG machine (which is what you’d find at a doctor’s office and nearly 100% accurate), the Apple Watch measured roughly 91% accuracy. 

This precision makes the Apple Watch deal for anyone who wants to see how hard they’re working while exercising and can also provide information on other important health aspects, such as sleep disorders or irregular heartbeats.

For instance, Desai says that “a spiking heart rate during sleep can sometimes indicate sleep apnea where someone stops breathing due to airway obstruction or brainstem respiratory drive.”

How variable your resting heart rate is can also indicate stress levels, since your heart rate tends to spike when you’re stressed.

2. ECG 

The Apple Watch’s electrocardiogram (ECG) app is one of the most influential features it offers. According to the Mayo Clinic, the app records cardiac electrical signals, which can detect heart problems like irregular rhythms. 

Although the Apple Watch can’t tell you your arteries are clogged or you have a heart attack, the ECG app’s data can give doctors a clearer picture of what might be going on if you’re experiencing certain symptoms like chest pain or tightening, shortness of breath, palpitations, or dizziness and lightheadedness. 

To use the functionality, open the ECG app on your watch and hold your finger on the crown for 30 seconds while resting your arm on your lap or a table. After the reading, the watch tells you if you show signs of irregularity.

Desai says studies haven’t agreed on this app’s accuracy, but the data is solid info in his opinion that he still instructs his patients to use this feature in order to monitor heart murmurs or atrial fibrillation (Afib or AF). 

3. Fall detection 

Fall detection can be a highly useful feature for older folks, or anyone who uses an Apple Watch to hike, bike, or climb outdoors. 

Once the watch notices you’ve fallen, it vibrates and sounds an alarm on your wrist while also displaying a visual alert. You can choose to notify emergency services or dismiss the alert altogether.

Additionally, if the watch detects no movement for roughly a minute, it starts a 30-second countdown with vibrations and sounds. If there’s still no movement, it automatically calls for help and sends both an alert and your location to your emergency contacts. 

4. Blood oxygen readings

One of the more impressive features the Apple Watch offers is its blood oxygen sensor. When used, it’s able to measure the oxygen saturation of your blood in roughly 15 seconds.

To log a reading, the watch’s built-in optical heart sensor shines red and green LED light and infrared light onto your wrist to measure the amount of light reflected back. It then uses an algorithm to calculate the color of your blood; bright red blood has more oxygen while dark red blood has less. 

Healthy blood oxygen saturation levels range from about 95% to 100%. The Cleveland Clinic says to visit a doctor if your blood oxygen saturation level is lower than 92% and to head to an emergency room if less than 88%. Certain conditions like lung disease may affect blood oxygen saturation levels, too, so it’s always smart to consult a doctor about what should be your typical reading.

Low blood oxygen levels can lead to organ damage and may indicate issues in your lungs or circulatory system.  

5. Noise level notifications

Apple’s Noise App measures nearby sounds and can detect both how loud a noise is as well as how long it lasts. 

If you’re around loud noises for too long, or the noises reach an unsafe decibel level, the watch will alert you with a short vibration.

The app can also notify you if you’ve had long-term exposure to sounds above 80 decibels. However, you can turn this feature off completely or set it to alert only at certain intervals from 80 to 100 decibels. 

According to the CDC, being around noises above 70 decibels for an extended period of time can lead to damaged hearing. 

6. Medication tracking

Medication tracking is a feature baked into the Health app that’s designed to not only keep track of your medications and supplements but to alert you as to when it’s time to take them. The app also allows you to make a logged entry of all consumed medications to help keep track of when and how much you’ve taken. 

Apple’s medication tracking can also inform you about any negative interactions between the drugs you take and other substances. For example, it can alert you if consuming alcohol while on certain medications could lead to a serious reaction. This feature requires users to upload a photo of the label of their medications, and all warnings associated with it will then be added to their Health app and profile. 

7. Afib history

Being able to easily track your Afib history is a major benefit for Apple Watch wearers. 

Afib is a disorder that leads to the heart beating quickly and irregularly. Although some people may experience brief heart rhythm variations, the constant irregular heartbeat related to Afib can raise the risk of stroke or heart failure in certain folks.  

If you’ve been diagnosed with Afib, you can use this feature to track how often your heart rhythm changes, and whether it’s serious enough to need medical care. 

The companion Health app can also keep track of what might be affecting your Afib, like sleep, exercise, and weight. It can also identify when arrhythmias happen most frequently, like the time of day or a certain day of the week, which could help a doctor know what to prescribe or if other treatments or procedures are necessary 

8. VO2 Max 

Tracking your VO2 fitness levels or maximum oxygen consumption can tell you your overall cardio health by measuring the maximum amount of oxygen your body takes in during a workout. 

According to the Exercise Physiology Core Laboratory at the University of Virginia, your VO2 max measurement is “generally considered the best indicator of cardiovascular fitness and aerobic endurance.” 

The watch uses the heart rate monitor and motion sensors during activities to configure your VO2 levels. 

A higher VO2 level means your body is capable of taking in more oxygen. This is especially important during cardio exercises like running, swimming, or biking when your body requires a higher oxygen intake. 

Typically people who are in good shape have a VO2 max ranging from 42 to 47 for males and 33 to 36 for females, whereas people who live a more sedentary life are in the range of 35 to 40 for males and 27 to 30 for females.

Insider’s takeaway

The Apple Watch can be a highly beneficial health tool for anyone who wears one, so long as you take advantage of everything it offers. 

Having the ability to quickly view things like your heart rate patterns, VO2 levels, or blood oxygen saturation is vital information whether you’re extremely active or you need to keep tabs on any conditions you might have.

This is especially true for those with Afib or any other kind of irregular heartbeat condition or folks who take a lot of medications and need a reliable way to track everything. And for anyone who keeps active, the accurate heart rate monitor and blood oxygen readings can provide valuable information about the effectiveness of their training.