Apple adds SpO2 & V02 Max to Apple Watch Series 6, and launches three new studies

The new sensor brings Apple up to speed with its competitors, but could lead to bigger announcements down the road.
By Jonah Comstock
03:04 pm

Apple announced today at a virtual event that its upcoming Series 6 Apple Watch will include a blood oxygenation sensor, a first for the Apple Watch (but not for the wearable space). As it did with the ECG, Apple is launching a set of partnered research studies using the new capabilities of the Watch. Additionally, WatchOS7 will use existing sensors to measure a lower range of VO2 Max values.


Apple COO Jeff Williams described the new sensor and some of its functionality during the presentation.

“With Apple Watch Series 6, you can measure your blood oxygen right from your wrist,” he said. “The new health sensor in Series 6 shines red and infrared light onto your wrist and measures the amount of light reflected back. Advanced algorithms use this data to calculate the color of your blood, which indicates the amount of oxygen present. The new blood oxygen app lets you take a measurement in just 15 seconds. The Series 6 also captures periodic background readings and stores them in your health app. So if you wear your Apple Watch to bed, it can record background measurements while you sleep.”

While the use of the new sensor in research studies suggests a degree of clinical accuracy, Apple’s VP of Health Dr. Sumbul Desai described the app as letting users measure blood oxygen “for fitness and wellness purposes.”

The three research studies Apple is embarking on include:

  • A study on controlling asthma using physiological signals, in partnership with the University of California, Irvine, and Anthem.
  • A study on how metrics, including blood oxygen, can be used to manage heart failure, in partnership with the University Health Network and the University of Toronto.
  • A study on how heart rate and blood oxygen can signal an early onset of respiratory conditions like flu and COVID-19, with the Seattle Flu Study and the University of Washington School of Medicine.

As for the VO2 Max capability, it will estimate that value, which is considered a strong predictor of overall health (but can be hard to measure outside of specialized clinics) using the Watch’s motion sensor and heart rate sensor. Later this year, a feature will be added allowing users to be notified about a drop in VO2 Max.


This new sensor does round out the Apple Watch’s health tracking capability, but it is far from groundbreaking. Fitbit added SpO2 more than two years ago and Withings added VO2 Max around the same time  and even that put it a year behind Garmin.

But because of its huge reach and multi-function nature of Apple Watch, the company can afford to play the role of fast follower with its health sensors – especially if the final product ends up effective and easy to use.

And there's reason to believe Apple has improved on the formula. A press release on Apple's website offers some additional details about how the sensor will function, adding that it employs four clusters of LEDs "to compensate for natural variations in the skin and improve accuracy." This looks like a nod to criticisms that came to light last year about devices like the Fitbit not working as well for people with dark skin.

Apple also relies on what it calls “sensor fusion” for a lot of its health-sensing features, and from that standpoint an additional sensor opens the door for bigger announcements down the line. For example, when Fitbit added blood oxygenation there was speculation the company was working on sleep apnea detection.

For Apple, that kind of early detection would line up well with its irregular heart rate and fall-detection features, thus positioning Apple Watch as a useful everyday device that might also save your life.


“As you breathe, your heart and lungs work together to deliver oxygen throughout your body,” Desai said. "Blood oxygen saturation is an indication of how well the system is functioning and of your overall respiratory and cardiac health, and pulse oximetry is how you measure it. Now the Blood Oxygen app on Series 6 lets you measure your blood oxygen for fitness and wellness purposes from your wrist anywhere and at any time. This is a great new tool for your overall wellbeing.”


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