One of the valuable, and lesser-known health features on Apple Watch is Cardio Fitness. The measurement is based on your VO2 max which Apple Watch can estimate when recording certain workouts. Follow along for a look at how to use Cardio Fitness on Apple Watch and iPhone including why it’s important, how to set it up, and how to measure/view Cardio Fitness levels.

Cardio Fitness background

Whether you’ve just recently gotten an Apple Watch or have had one for a while and haven’t used Cardio Fitness before, it’s a valuable measurement to understand and use.

Table of contents

  • Cardio Fitness background

  • How to use Cardio Fitness Apple Watch and iPhone

  • Setup

  • How to measure Cardio Fitness with Apple Watch

  • How to view Cardio Fitness levels on iPhone

  • Setup

  • How to measure Cardio Fitness with Apple Watch

  • How to view Cardio Fitness levels on iPhone

Here’s how Apple describes it:

By measuring the “body’s ability to take in, circulate, and use oxygen” Cardio Fitness is a metric that gives a good indication of overall health and can also predict long-term health. While there’s a correlation between low Cardio Fitness levels and future health issues, you’ve got the power to raise your levels with consistent aerobic exercise 🙂.

Apple Watch users can view their cardio fitness level in the Health app on iPhone, and receive a notification on Apple Watch if it falls within the low range. Breakthrough technology released in watchOS 7 allows Apple Watch to easily measure low cardio fitness, and today cardio fitness notifications empower users to be more active for dramatic long-term health benefits.

Cardiorespiratory fitness, as measured by VO2 max, is the maximum amount of oxygen the body can use during exercise, and it can be increased through physical activity. Apple Watch already estimates average and higher levels of VO2 max during vigorous outdoor walks, runs, or hikes, which many runners and other athletes monitor to improve performance.

And another great supplemental resource to track heart health is with the Withings “Vascular Age” feature on its latest Body Cardio smart scale.

  • Review: Withings Body Cardio smart scale with Apple Health now features Vascular Age

How to use Cardio Fitness Apple Watch and iPhone

Setup

  • If you haven’t set it up before, open the Health app on your iPhone
  • Tap Summary and swipe down near the bottom and look for Cardio Fitness (under “Get More From Health”)
  • Choose the blue Set Up button
  • Follow the prompts like confirming your health details (users must be at least 20 years old)
  • You can choose to turn Low Cardio Fitness Notifications on for your Apple Watch
  • Now you’ll see Cardio Fitness show up under the Heart section in the Health app

How to measure Cardio Fitness with Apple Watch

  • You won’t see Cardio Fitness level data points for every workout recorded with Apple Watch, here’s what Apple says:
  • Apple Watch can record an estimated VO2 between 14 and 60 mL/kg/min when you do a brisk hike, walk, or run outdoors with persistent heart rate measurement. It can estimate your VO2 max if you start one of those workouts in the Workouts app
  • VO2 max is validated for users 20 and older. Most people can improve their VO2 max with more intense and more frequent cardiovascular exercise. Certain conditions or medications that limit your heart rate may cause an overestimation of your VO2 max. You can indicate you’re taking certain medications in the Health Details.
  • You can read more specifics about Cardio Fitness in the Cardio Fitness section in the Health app.

Interestingly, Cardio Fitness levels will show up even for outdoor walk/hike/run workouts that you’ve previously done. You can tap the timeframe icons at the top of Cardio Fitness to see daily, weekly, monthly, and yearly data (see more on this below).

  • Apple Watch can record an estimated VO2 between 14 and 60 mL/kg/min when you do a brisk hike, walk, or run outdoors with persistent heart rate measurement. It can estimate your VO2 max if you start one of those workouts in the Workouts app
  • VO2 max is validated for users 20 and older. Most people can improve their VO2 max with more intense and more frequent cardiovascular exercise. Certain conditions or medications that limit your heart rate may cause an overestimation of your VO2 max. You can indicate you’re taking certain medications in the Health Details.
  • You can read more specifics about Cardio Fitness in the Cardio Fitness section in the Health app.

Apple notes that cycling is another great aerobic exercise to improve Cardio Fitness, but for now, it doesn’t look like tracking Cycling workouts on Apple Watch will record Cardio Fitness data.

How to view Cardio Fitness levels on iPhone

  • You can look at your Cardio Fitness levels any time by heading to the Health app

  • Tap Browse > Heart > Cardio Fitness

  • Tap the blue “Show All Cardio Fitness Levels” to see all your available data

  • Now you can see the months you’ve been in the low, below average, above average, and high categories

  • If you happen to have another device that measures VO2 max (or have gotten it professionally measured) you can tap “Add Data” in the top right corner to manually add measurements

  • You can read more about why Cardio Fitness is important and how to increase it in the Health app – but the simplest and biggest factor is regular aerobic exercise 😎

  • Apple Watch: How to see your detailed heart rate history

  • Apple Watch: How to see calories burned – active, passive, and total

  • Best USB-C and Thunderbolt displays for Mac [January]

  • How to take a scrolling screenshot on iPhone