Here’s how and why you should set up cardio on your Apple Watch and iPhone

One of the valuable and lesser-known health features of the Apple Watch is cardio fitness. The measurement is based on your VO₂ maximum that Apple Watch can estimate when recording three specific workouts. Follow along to learn how to use cardio on Apple Watch and iPhone, including why it’s important, how to set it up, and how to measure/view your cardio levels.

Fitness cardio background

Whether you just bought an Apple Watch or have had one for a while and haven’t used cardio, it’s an invaluable measure to understand and use. Here’s how Apple describes it:

“Cardio fitness is a measure of your VO₂ max, which is the maximum amount of oxygen your body can consume during exercise. Your level of cardio fitness is a strong indicator of your overall physical health and a predictor of your long-term health.

The reason it’s an accurate indicator of overall health is that cardio fitness is based on measuring the body’s “ability to absorb, circulate, and use oxygen.” While there is a correlation between low levels of cardiovascular activity and future health problems, you have the power to raise your levels with consistent, more intense aerobic exercise.

Two other valuable ways to monitor heart health are heart rate variability (HRV) and Withings’ “Vascular Age” feature on its latest Body Cardio smart scale.

How to use cardio fitness Apple Watch and iPhone

Setup (Apple Watch Series 3 or later required)

• If you haven’t configured it before, open the file Health apps on your iPhone
• Faucet Summary and scroll down near the bottom and search Cardio fitness (Under ‘Get More from Health’ you can also search Browse > Heart > Cardio Fitness)
• Choose blue Setting up button
• Follow the instructions how to confirm your health data (must be at least 20 years old)
• You can choose to turn on low cardio fitness notifications
• You will now see cardio fitness appear under the Heart section in the Health app

How to measure cardio fitness with Apple Watch

• You won’t see cardio fitness data 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 take a quick hike, walk or run outdoors with continuous heart rate measurement. It can estimate your VO₂ max if you start one of these workouts in the Workouts app
  • VO₂ max is validated for users aged 20 and older. Most people can improve their VO₂ max with more intense and more frequent cardiovascular exercise. Certain conditions or drugs that limit your heart rate can cause your VO2 to be overestimated₂ max. You can indicate that you are taking certain medications in the Health Details.
  • It can take at least 24 hours to wear your Apple Watch, followed by several workouts and passive measurements with your Apple Watch before you receive an initial quote
  • You can read more details about the feature in the cardio fitness section of the Health app.

Cardio activity levels will also appear for any outdoor walk/hike/run workouts you’ve done previously. You can tap the time period icons at the top of cardio fitness to view daily, weekly, monthly and yearly data (see more below).

Apple notes that cycling is another great aerobic exercise to improve cardio fitness, but for now, cycling workouts on Apple Watch won’t record cardio fitness measurements.

How to view cardio fitness levels on iPhone

• See your cardio fitness levels anytime by going to the Health app on iPhone
• Faucet Browse > Heart > Cardio Fitness
• Tap the blue “Show all cardio activity levels” to view all available data
• You can now 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 you have measured it professionally) you can tap “Add data” in the upper right corner to add measurements manually
• You can read more about why cardio is important and how to increase it in the Health app, but the simplest and most important factors are increasing the intensity and frequency of your aerobic exercise

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