Cardio Fitness levels feature on Apple Watch, here’s what you should know

Apple Watch and Apple Health app cardio fitness levels

Apple’s Health app offers a feature called Cardio Fitness levels. Although this looks like a new feature, it’s actually rebranding the older VO2 max. Apple renamed VO2 max to Cardio Fitness–to make it more user-friendly!

We really like this rebrand because the Cardio Fitness feature lets users know via notifications if they are trending with low cardio fitness levels.

Related reading:

Why your cardio fitness matters

With this update, Apple is leveraging VO2 max scores to show a user’s cardio fitness levels.

Cardio fitness is a strong indicator of your physical health. You maintain or improve your cardio fitness with physical activity.

And conversely, a decrease in physical activity also corresponds to a lowering of your overall cardio fitness level.

What factors determine your cardio fitness?

Many factors determine your cardio fitness levels. The primary determinants are age, sex, lung conditions, and heart conditions (resting heart rates.

VO2 max is the gold standard for establishing and personalizing each person’s cardio fitness level.

VO2 Max stands for V (volume)  + O2 (oxygen)  + Max (maximum). It measures the maximum amount of oxygen your body can use while exercising or engaging in physical and aerobic activity.

The Apple Watch leverages the VO2 max standard to determine and assign a score for your cardio fitness level.

What is a good score for Apple’s cardio fitness level (VO2 Max)? Cardio fitness above average from Apple Watch and in iPhone Apple Health app

Apple Watch leverages the VO2 max score to determine each person’s Cardio Fitness level value. Apple bases your cardio fitness score based only on these exercises: Outdoor Walks, Outdoor Runs, or Hiking workouts in the Apple Watch Workout app.

Your cardio fitness level measures how hard your heart and the score itself depends on your age, gender, weight, height, and any medication you take that could impact your heart. This feature is available for anyone 20 years or older.

According to Apple, for men ages 30-39, an average score should be above 43, while for women of that same age, it should be above 30.

Generally, varying VO2 max scores indicate (depending on age and gender)

  • Scores between 15 (60 years old+) – 29 (under 30) signify a low cardio fitness level. 
  • A score between 25 (60+) – 53 (under 30) is considered average to above-average cardio fitness.
  • Anything between 32 (60+) – 54 (under 30) qualifies as a high cardio fitness level.

However, this dramatically varies with a person’s age and gender.

For example, a female above 60 years old is considered low at 15, above average at 20, and high at anything above 25!Good Cardio Fitness level score on Apple Watch

So it’s crucial to review the cardio fitness levels for your current gender and age before checking your current cardio fitness level.

The philosophy behind this change is apparent from Apple’s guidance:

In a 2016 scientific statement, the American Heart Association recognized a growing link between low cardio fitness and a higher risk of significant health issues, such as heart disease, high blood pressure, and obesity, later in life. Research even suggests cardio fitness is a stronger predictor of mortality risk than common risk factors like smoking, diabetes, and hypertension.
“Cardio fitness is increasingly recognized as a powerful predictor of overall health, and we are making it even more accessible to more people,” said Jeff Williams, Apple’s chief operating officer. “Using its advanced sensors, Apple Watch now brings estimation of low cardio fitness levels from clinics directly to a user’s wrist, so people have more insight into how they can improve their long-term health through daily activity.”
If Apple determines that your cardio fitness levels are low for your age and gender, you receive a low cardio fitness notification on your watch and from the Health app. Apple Watch low cardio notification
When your cardio fitness levels remain low, you get additional notifications until the Health app detects an increase into average or better levels.

How to enable or disable Cardio Fitness Level notifications on your Apple Watch

The cardio fitness level notifications are easy to enable or disable using the Watch app on your iPhone.

  • Open the Watch app on your iPhone.
  • Tap on ‘My Watch’ at the bottom.
  • Next, tap on Notifications and scroll down and select ‘Heart.
  • Find ‘Cardio Fitness Notifications’ here.Enable or Disable Cardio fitness level notifications
  • Toggle the setting on to enable or off to disable these notifications.

Per Apple, if your cardio fitness level stays low for an extended period (months, not days), you receive a notification every four months.

Since the calculation of Cardio fitness level depends on your resting heart rate (RHR), Apple recommends you wear your watch when you sleep to get an accurate score.

Typically individuals with higher VO2 Max have lower heart rates while running at the same pace as individuals with lower VO2 Max.

See these articles to troubleshoot problems with cardio fitness data on your Apple Watch:

Why does Apple call it cardio fitness instead of VO2 Max?

The VO2 max health metric isn’t well-known, and for most people, there was a lot of confusion around it. Indeed, most people ignored it because they didn’t understand it!

Hence, Apple rebranded it as an overall Cardio Fitness Level score on the Apple Watch and the Health app.

And most of us know what both cardio and fitness mean–and can easily translate it into our heart’s health.

Cardio Fitness Level on Fitbit
Fitbit app Cardio Fitness level score

Apple is not the first when it comes to using this term.

Fitbit also uses a Cardio fitness score via the Fitbit app and calculates it using the VO2 max metric.

How does Apple Watch determine low or high Cardio Fitness score?

Apple uses the established FRIEND database to look up reference values by sex and age and compares it with the readings collected from your Apple Watch to determine low or high Cardio Fitness score.

The Fitness Registry and Importance of exercise national database (FRIEND)  is a repository that holds reference values for VO2 Max / Cardio Fitness scores. 

These are the first cardiorespiratory fitness reference data using measures obtained from CPX (cardiopulmonary exercise testing), the gold standard for VO2 Max, in the United States. 

FRIEND can be used to provide a more accurate interpretation of measured VO 2max from maximal exercise tests for the US population compared with previous standards on the basis of workload-derived estimations.

What causes Inaccurate Cardio Fitness score readings on Apple Watch?

Having said that, there are some factors that influence the accuracy of cardio fitness score and these have been highlighted by Apple in its research paper. We highlight the most important ones for you below:

  1. The user has not updated personal details on the Apple Health app. If you enter an incorrect age, sex or weight, you may consistently see inaccurate VO2 max estimates.
  2. Pregnancy can cause inaccurate estimates for VO2 max
  3. Cardio Fitness scores will be low as per Apple, if sensor data is recorded during behaviors that increase user’s work load in a way that Apple Watch can’t detect.
      • Apple Watch may show you inaccurate reading if you are running or walking on sand or any surface that increases your effort.
      • You are running with a backpack carrying extra load
      • Factors that increase heart rate, such as dehydration, caffeine intake, extreme heat, or recent transition to high altitudes may also lead to underestimates.

The 5.75 Minutes mystery for Apple Watch Cardio Fitness score

Although Apple’s guidance says three minutes of activity, their research also shows that the optimal number of exercise minutes to generate a VO2 max or Cardio Fitness score is 5.75 minutes.

93% Percentage of participants who completed at least 10 outdoor pedestrian workouts longer than 5.75 minutes and received at least one estimate in their first 10 workouts

79% of outdoor pedestrian workouts longer than 5.75 minutes received an estimate.

Bottomline, if you just purchased an Apple Watch, you may have to workout for at least 10 regular outdoor runs/walks/hikes in order to increase the chances of seeing your accurate VO2 max score.

How do you improve your Cardio fitness level score?

Exercise and healthy weight loss are two ways to improve your Cardio fitness level score. 

  • Weight loss lowers your body fat percentage and helps with improving your cardio fitness levels.
  • Increased exercise helps you improve your cardio fitness score by up to 20 percent over two to three months (source: Kennedy, Phys. of Sport and Exer.). 

How much exercise do I need to get an average cardio fitness score?

Recent results from Apple’s Heart and Movement Study (in collaboration with Brigham and Women’s Hospital and American Heart Association) indicate that how much activity you engage in each week really matters. 

Across genders and ages, participants with above-average Cardio Fitness levels averaged more than 200 minutes of activity per week, while those with high Cardio Fitness averaged more than 300 minutes of activity per week

To improve overall cardiovascular health, the American Heart Association recommends at least 150 minutes per week of moderate exercise or 75 minutes per week of vigorous exercise (or a combination of moderate and vigorous activity.)

Tip: Add high-intensity interval exercises!

Incorporating high-intensity intervals in your workouts is an effective way to see a noticeable improvement. But don’t forget to also do your outdoor walks, hikes, or runs to get Apple to measure your cardio fitness.

Interval training includes any workout that alternates between intense bursts of activity followed by a lower-intensity activity or rest periods.

This type of episodic interval training has proven to be one of the best levers to increase your VO2 max and, therefore, your cardio fitness level.

Apple Fitness+ Workout Modes

This is where Apple Fitness+ comes in handy!

Apple’s Fitness+ subscription offers several trainer-led classes that focus not only on High-intensity interval training.

But these workouts also guide users through activities that improve their Cardio Fitness levels.

Plus, all classes offer modifications so people of any fitness level can join in!

Apple's Fitness Plus new BURN BAR

As a Fitness+ student, Apple’s unique Burn bar is another excellent feature to leverage.

The Burn Bar shows how your current workout intensity and effort stack up against anyone who previously did that same workout.

This Burn Bar helps you push through your workout to get the most out of high-intensity fitness training classes for people who love a little competition.


Understanding your cardio fitness level helps you know more about yourself and take ownership of your body and exercise routines.

How do you stay fit today and access your overall cardio performance?

What features on the Apple Watch help you assess your overall fitness levels?

Please let us know using the comments below.

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Sudz Niel Kar
I am a technologist with years of experience with Apple and wearOS products, have a BS in Computer Science and an MBA specializing in emerging tech, and owned the popular site AppleToolBox. In my day job, I advise Fortune 500 companies with their digital transformation strategies and also consult with numerous digital health startups in an advisory capacity. I'm VERY interested in exploring the digital health and fitness-tech evolution and keeping a close eye on patents, FDA approvals, strategic partnerships, and developments happening in the wearables and digital health sector. When I'm not writing or presenting, I run with my Apple Watch Ultra or Samsung Galaxy Watch and closely monitor my HRV and other recovery metrics.


  1. I agree with what mostly everyone is commenting that I’m the Apple Watch readings are inaccurate.

    Additionally, Apple does not make it clear or easy to get accurate readings from them. You must set up a “Bedtime” to allow sleep tracking to be activated, make sure the toggle is on, and subsequently track your sleep.

    You also must perform workouts using the native Workout app, with the only three contributing toward the Cardio Fitness measurement being Walking, Running, or Hiking, while remembering to tap stop on the watch to end your workout.

    If you don’t, the rest of the workout data is garbage fed to the cardio fitness measurement, with no way to delete portions of a workout to present accurate data (e.g., I start an open goal outdoor walking workout that will be about 2 miles on a walk to the vehicle. I hop in so I can get the AC going and start driving, forgetting that a workout is in progress. My watch doesn’t ask if I’m done for an absurd amount of time. I tap end workout, and it still logs the portion that I was “walking” without my wrists moving and going 30 mph. You can’t delete the portion after you get in your car.)

    All of this user intervention and complexity needs to be done away with.

    Apple should use the plethora of sensor data gathered from my watch in the background and figure it all out. If it wants to make readings more often impacting battery, notify me, and I’ll say yes, read more; I use my Ultra quite casually and charge before bed so my battery can take it. That should be the Apple experience.

    What they have now, including the workout app itself, is awful. And they’ve had watches out for 10 years now.

    Lastly, and most importantly. Please. Anyone who is commenting on the problems or insufficiencies with the cardio fitness level leaves the same comment to Apple feedback.

    Voice your concerns, displeasure, and suggestions: if you’ve already posted on this website, then just copy and paste it to Apple.

    • *Edit for my above comment

      Apple Watch DOES NOT use data from Sleep Tracking to include for estimating your resting heart rate. I was wrong about sleep tracking. You do not need to have that turned on.

      Apple still needs to make the experience effortless with the results accurate.

      Adding a note under the Cardio Fitness Notification toggle that states, enabling this will take readings for heart rate and gps more frequently and intelligently, slightly increasing daily battery usage.”

  2. I’m 90 next year and try to stay fit. My reading comes out as’ below average.’ The data that is used only goes to 65+.

    If one extends the existing age trend to beyond 65 then my reading becomes ‘above average.’

    However, this does assume that the linear trend continues. This must be checked, and the FRIEND data extended beyond 65.

    The comments by everyone above show that there are many of us in this age group very interested in measuring and improving our fitness.

    • Hi Ron,

      I totally agree, especially since we live in an age where people live longer, healthier lives–much longer than 65 years old.

  3. The AppleWatch only uses walk, run, and hike to measure cardio fitness.

    I’m a mountain biker and I get most of my cardio from that and HIIT, but the watch doesn’t use either of those to calculate cardio fitness.

    As a result I rarely get readings and they are low when I do. This is ridiculous and needs to be fixed by Apple.

  4. I am 86 and male….my Vo2 is 29.7…has been as high as 35….have made no changes to health workouts of 6+hours a week…got a low warning recently.

    I don’t run but walk a dog every day for about 1.5 hours…3.5 miles total..but dog stops frequently, and those walks take extra time and its those walks I think dragging down my Vo2.

    My gym workouts don’t seem to count in my Vo2 score. I burn 500-600 calories /day. I sleep with watch and have very good low heart rate…50-60..I am not happy with Vo2 only measuring walks and runs…Apple needs to make some changes in how they measure Vo2.

    • Hi Donald,

      Yes, I have the same problem with my 2X daily outdoor dog walks! And it is frustrating that when I hit the gym and do a combo of cardio on the bike, treadmill, or rower along with strength training, that none of that is included in the cardio fitness score.

      Hopefully, Apple makes some changes to it since it can be discouraging to engage in all these fitness activities yet see no results or movement in those cardio fitness scores!

  5. I agree with Cam Bradley. I too am 80, walk every day, am very active and I was alarmed that my cardio is showing 18 but my BP is low for my age and my pulse is around 60. Something just does not add up!!!

  6. To have my Apple Watch suddenly announce to me that I have LOW Cardiofitness Level has been VERY upsetting – panicking!

    My first thought was that I had better get to my CardioDoctor immediately. How can you program a watch that tells one such a dire situation on very little data? I cannot see how this can be true for me – 80 years, exercise a lot, regularly, eat and sleep well.

    It’s too frightening and perhaps presumptuous.

  7. I have found that I only get an update in health on my cardio fitness score, if I have selected one of the workouts (like Outdoor Walk) and I have to properly stop the workout at the end but ALSO I have to scroll down on the summary on my watch and tap done. Then it immediately scores my cardio fitness to be viewed in Health.

  8. My cardiac fitness with my Fitbit Versa was excellent as is my actual fitness but Apple Watch determines that I have low fitness.

    I sleep with my watch on and exercise with the watch on. I am 74 but very fit-I still can run and I do high-intensity circuit training.

    • Hi Jesse,

      Apple Watch uses only outdoor runs, outdoor walks, and hikes logged with the Apple Watch Workout app (not any third-party apps) to determine its cardio fitness (VO2 Max) score. So if you do high-intensity circuit training, that workout isn’t counting towards the score.

  9. Cardio Fitness in not working properly on Apple Watch, this is a fact!

    Loads of people are complaining about it on different forums. I am very active, regularly running and doing very long walks. The watch kept showing data going upward continuously in the first 6 months, then suddenly started dropping and it keeps going down ever since, even though my lifestyle is exactly the same.

    I unpaired and re-paired my phone and watch a month ago and it jumped up again, then after a while it started dropping down again.

  10. My cardio fitness is not coming up at all. This is a big disappointment for me since I am new to Apple Watch. I had a Fitbit before and was having no trouble with obtaining my fitness score. Please help

    • Hi Christie,

      You only receive a cardio fitness notification if your cardio fitness levels are low for your age and sex.

      If you don’t get any notification, check inside the Health app for cardio fitness info.

        Open the Health app on your iPhone and choose Browse
        Tap the Heart category and choose Cardio Fitness
        Tap D, W, or Y to view your average for the Day, Week, or Year
        Tap Show All Cardio Fitness Levels
  11. Hi, I think seniors are penalized on watch. I am a 76-year-old male.
    My level has increased from 26.8 in April when I got the watch to now consistently 27.8 and below average.

    The watch puts me in the 60+group. The age range chart lowers 5 oints per decade but up to 60 and stops.

    When you are 76 you will realize from 60 to 76 is a bigger change in wellness overall than going from 49 to 50.

    Apple needs to adjust the watch reading for seniors. Thank you.

  12. Hello.

    I’m trying to find info about how often my Apple Watch measures Cardio Fitness Level.

    It hasn’t given a new measurement since July 4th.

    And yes, I do sleep with it on. Thanks in advance!

  13. Hi, my name is David, and I have a relatively new Apple Watch.

    The cardio fitness measured on the high level for several months and then all of a sudden went down to below average from about 50 down to 25 where it stays.

    I walk about three or 4 miles a day and have fairly good health.

    Nothing seems to have changed and I’m wondering if the watch has a defective measurement light or something else that could cause this to all of a sudden go from above average to below average.

    My cardiologist took a look at it and thought that the watch wasn’t very accurate. I’m still not satisfied

    • same here! while I am very active, averaging more than 90 minutes of aerobic activities a day, my VO2 max has been significantly lower as estimated using my apple watch.

      I am 75 years old personal trainer and Wellness Coach. I am certified to conduct submaximal VO2 max testing using a treadmill or ergometer.

      Over the past few years, my apple watch estimates of VO2 max have dropped from > 35 ml/min/kg BW to less than 16 ml/min/kg BW.

      I’m having a maximal VO2Max test (gold standard) done on December 18, 2022.

      I will post my results then as a follow up with a detailed comparison. I realize that it is a sample size of only one, but specific for me and not the norms!

  14. Hello. I thought of sharing my feedback to correct the issue if any in calculating VO2 max.

    I recently shifted from Fitbit to Apple watch… my cardio fitness levels were recorded as “Excellent” for the past 2+ years with a score of 51-54 in my Fitbit, however, apple showing a range of 35-37 this is below average range..

    I assume a change in the device should not show much variance.. earlier one very well matching with my fitness level and workout, however, data from apple which is indicating a different fitness level, which one to believe?

    if need data from both devices for reference happy to share it.

    Regards, Ananda Rao. C

    • Ananda Rao. C,

      Hi Ananda,

      Are you wearing your Apple Watch when you sleep? Wearing it while sleeping gets a better resting heart rate estimate than during the day. So try wearing your Apple Watch overnight and see it makes any difference in your cardio fitness level according to Apple Watch.

      Also, verify that your information for age, gender, weight, and other personal information is correct.

    • Hi, After going through the replies in this forum, it is pretty much clear that Apple are clueless in the VO2 max department!

      I had a galaxy watch active 2 before upgrading (or downgrading in retrospect!) to an Apple Watch 7.

      I used to consistently record VO2 max figures in the range of 51-54 on the Samsung, whereas the highest I have achieved on AW7 is 39, which for my age and gender, is below average.

      And yes, I have followed all the recommendations to obtain a good cardio fitness reading, including sleeping with the watch on, manually starting and stopping workouts, and trying out a variety of workouts like running, swimming, cycling, walks, etc. I really hope they solve this issue through a software update in the near future.



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