How Does Apple Watch Calculates VO2 max?

Apples Watch Series 3 and later version includes VO2 max features that can measure the user’s cardio fitness level. VO2 max feature is popular among fitness enthusiasts as it tells your body’s overall wellness.

Today’s article will discuss what VO2 max is, how the Apple watch measures VO2 max and its benefits.

So let’s started. 

What is VO2 Max?

Before discussing the working of VO2 max in Apple watches, let’s know what VO2 max is.

VO2 max measures the amount of oxygen an individual can extract from inhaled air and then transport by your blood to muscles. This oxygen is converted into energy during workouts; the latest Apple algorithm uses this feature to evaluate cardio fitness. 

The values of VO2 max are typically normalized for human body mass and measured in ml/kg/min. VO2 max may vary from person to person. In the elderly, it normally declines. 

How Does Apple Watch Measure VO2 max?

Apple Watch Series 3 and later versions automatically use updated algorithms to track your VO2 max over time. The Apple watch will take VO2 max readings if you perform any physical activity or workouts for more than 20 minutes. The VO2 max features use a heart rate optical sensor to estimate VO2 max. 

For testing VO2 max feature Apple suggests performing high-intensity exercise while wearing a face mask. This will allow users to measure the oxygen level in inhaled and exhaled air directly. 

If you want to get accurate VO2 max results of your activity, start your activities before warm-up and then manually select workout on Watch. Perform your activity for at least 20 minutes, and your Apple Watch will automatically sync VO2 max results with Apple Health App.

According to Apple’s health research, your Apple watch may start tracking VO2 max if an exertion causes a 30% increase in HR from resting heart rate.

VO2 max— An Indicator For Cardio Fitness

vo2 max on apple watch

Apple named the VO2 max features “Cardio Fitness” since these features help you measure your high-intensity exercise performance. Apple algorithms measure how your body utilizes the maximum oxygen during exercise.

Sometimes the Watch automatically measures the VO2 max value during your cardio/high-intensity workouts. These metrics can be used to predict your body’s overall performance and wellness during different workouts. If your VO2 max value falls, the Apple watch will immediately notify you. 

Another scenario says that VO2 max measures the body’s ability to inhale, circulate, and use oxygen. After inhaling oxygen, it reaches your muscles via veins and converts to energy. The Apple watch measures how your body uses this energy during cardio fitness activities.

On your Apple Watch, Cardio Fitness is an estimation of your VO2 max in ml/kg/min. In Watch OS 7 and later versions, the advanced algorithms also calculate the lower ranges of cardio fitness (14 to 60 ml/kg/min) for users. 

Why Should You Check VO2 max?

Few people might ask a question: why should they need to track VO2 max as heart rate and SpO2 features are enough to track performance? VO2 max is pretty different from heart rate and SpO2, and it’s a measure of aerobic or cardiovascular fitness. VO2 max is considered an indicator of your overall wellness. 

VO2 max helps you to measure your current fitness level or stamina accurately. So you can choose the best fitness programs according to your current fitness state.

How You Can Determine VO2 max METS

Are you an Apple watch user? And wants to know more about VO2 max? We are going to share a methodology for figuring out VO2 max. VO2 max is also referred to as metabolic equivalent (MET) and 1 MET = 3.5 ml/kg/min. 

Studies also found a relation between VO2 max and your maximum heart rate. The following formula is used to find the relation between VO2 max and heart rate. 

VO2 max ≈ Heart Rate max / Heart Rate Rest ✕ 15.3ml/(kg.minutes)

Tips To Improve VO2 Max:

If you are an athlete or sports enthusiast, this section may be interesting. As mentioned earlier VO2 max can help you to know the effectiveness of your performance and overall wellness. Improving your VO2 max score means bettering your performance. 

Even if you are not a sports person, improving VO2 max might bring major changes in your overall health. According to research, increasing your Cardiovascular fitness is associated with benefits such as;

  • Healthier and active lifestyle
  • Increase lifespan
  • Reduce stroke risk
  • Reduce heart rate and diabetes
  • Improve mood
  • Improve sleep quality

To improve your VO2 max score, you should perform high-intensity activities. My fitness coach recommends activities at around 90 to 95 percent of your maximum heart rate. Such activities will burn more fats, improve blood circulation and strengthen the muscles in your heart. 

You can also add interval training to your fitness routine to produce better VO2 max results. Internal training includes high-intensity activities in short periods, so continuously performing such activities improve your Cardio fitness level.

How Can You Measure VO2 Max In Apple Watch?

If you haven’t set up the VO2 max feature on your Apple Watch, you can follow the steps mentioned above.

  • Open the Health app on your iPhone.
  • Tap Summary and then look for Cardio Fitness Levels
  • Now tap the Setup button
  • Confirm all your health details
  • You can also turn on low Cardio Fitness Notifications on your Apple watch
  • Here you go! Now you’ll be able to see the VO2 max section under the Heart section in the app.


Using Apple Watch Series 3 and later versions, you can measure your VO2 max. This will help you to keep an eye on your Cardio fitness. The features also allow users to receive notifications if their cardio fitness level is low. 

Usually, Apple watches automatically detect VO2 max, called Cardio Fitness on the Apple watch. Whether running, walking, swimming, or doing high-intensity workouts, your Apple watch estimates VO2 max.

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