How Does Apple Health Calculate VO2 Max?

VO2 max is one of the newer health metrics added to the Apple Watch in watchOS 7 which allows for users to get an accurate estimate of their cardiac fitness and the amount of oxygen they consume when they workout.

Apple Health calculates VO2 max using a series of algorithms that uses your resting and working heart rate to get an idea of your overall cardiac health over a series of workouts ultimately leading to an accurate calculation.

In this article, we’re going to explore exactly what VO2 max is, how it came out to be, how it is measured in the Apple Watch, and whether it is a useful feature to have in the first place.

What Is VO2 Max?

VO2 max is a measure of the amount of oxygen an individual can inhale from their surroundings which can then be metabolized in their body. It is a metric used medically to ascertain someone’s cardiovascular fitness as it involves an end-point measurement of the actual amount of oxygen a person consumes.

As someone ages, VO2 ends up declining and on the scale of a larger population, may also differ due to various other factors such as overall respiratory health, gender, and other physiological factors.

Why Is Measuring VO2 Max Important?

The measurement or decline thereof of VO2 max has been closely linked with various cardiovascular events that may be a cause for concern. The metric has also been used to link the following diseases with VO2 max:

  • Obesity
  • Hypertension
  • Hypercholesterolemia

So, the ability of an Apple Watch to seemingly estimate and accurately measure VO2 max allows for a significant chunk of the populous to be able to pre-emptively refer to a medical professional with prompt alerts being presented on the Apple Watch warning them of any trouble.

How Does Apple Calculate VO2 Max?

Apple calculates your VO2 max by using an algorithm that estimates the amount of oxygen you consume and your body metabolizes when performing rigorous physical activity. In essence, it measures your response to physical activity.

Currently, this feature is available with watchOS 7 and later and can be utilized by the Watch Series 3 and later. With watchOS 7.2, users can also now take a look at their Cardio Fitness levels based on their gender and age alongside receiving notifications on their cardiac health. 

To calculate your own VO2 max value, you’ll need to be on relatively flat ground and will need to be performing some sort of physical activity that exercises your heart. After wearing your Apple Watch for 1-2 days, you’ll be able to view your Cardio Fitness which is calculated using VO2 Max.

With iOS 14.3 and above, you’ll also be prompted as to whether you’d like to be notified if your current VO2 max levels are consistently poor enough for it to be an indication of a health issue or a lack of activity. 

These thresholds are dependent on the information you provide when first setting up your Apple ID. However, when onboarded and notified, you’ll need to consent to provide information such as your age, sex, and medications that you take in order to be eligible for the feature.

When going through onboarding, you will need to be extremely accurate with your medical profile and will also need to provide a list of all the medications you take. This is because some medicines can affect your VO2 max which may lead to inconsistent / inaccurate readings.

Is Apple Watch VO2 Max Calculation Accurate?

Yes, Apple has conducted extensive studies on the matter and has ample research with surveys to infer that VO2 max is an accurate estimate of one’s cardiac fitness. Moreover, with the extended range that watchOS 7.3 and later provide, you can now more accurately identify and evaluate your cardiac fitness which can be used to prevent / diagnose underlying cardiac issues before they come about.

Personally speaking, we recommend everyone to turn this feature on simply because of the utility it provides. Having the ability to find out whether your heart is doing well is one that we simply cannot take for granted especially because it does not require any external hardware or setting up for that matter. 

Primary Reference:

Using Apple Watch to Estimate Cardio Fitness with VO2 max

Secondary References:

Mora S, Redberg RF, Cui Y, et al. Ability of exercise testing to predict cardiovascular and all-cause death in asymptomatic women: a 9 20-year follow-up of the lipid research clinics prevalence study. JAMA. 2003; 290(12): 1600–1607. doi: 10.1001/jama.290.12.1600.

Clausen JSR, Marott JL, Holtermann A, Gyntelberg F, Jensen MT. Midlife Cardiorespiratory Fitness and the Long-Term Risk of Mortality: 8 46 Years of Follow-Up. Journal of the American College of Cardiology. 2018; 72(9): 987–995. doi: 10.1016/j.jacc.2018.06.045.

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How Does Samsung Galaxy Watch Measure Your Stress?

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I bought my first smartwatch in 2018 and have been wearing one ever since. It might get frustrating at times to receive 100 notifications a day. That's why we need to know how to make the best of them and how to use them to improve our daily lives, not the other way around. I write about the newest smartwatches, I create top picks, and I write helpful guides and simply explain complicated things.