A new Apple Watch alert tells you how fit (or unfit) you are. Here's how to get it
How to find your cardio fitness score on the Apple Watch -- and what it means for your health.
The Apple Watch is about to give you an honest review of your fitness levels. At a time when a lot of us are working from home or don't have access to gyms, fitness trackers like the Apple Watch have been helping us keep tabs on how much (or how little) exercise we've been doing on a daily basis. Now it's translating that data into a rating. Updating the watch's software to WatchOS 7.2, available now, brings a new cardio fitness score that uses your VO2 max (or maximum oxygen consumption during exercise) to gauge your cardiorespiratory health, or aerobic endurance.
Read more: Apple Fitness Plus is a workout routine that fits you
Cardio fitness explained
VO2 max is considered to be the gold standard for determining cardiorespiratory fitness and can be a good gauge of your overall health. Elite athletes use this metric for training purposes to gauge endurance, but its effects go beyond exercise. People with low cardio fitness levels are at greater risk of chronic health issues like heart disease, type 2 diabetes, colon and lung cancers, and early death, according to the American Heart Association. There are a number of different factors that can affect VO2 max like age, weight and even pregnancy, but as a general rule of thumb, the higher the number, the fitter you are.
An EKG machine shown at the Human Performance Center at UCSF.
The Apple Watch has been quietly keeping tabs on the estimated VO2 max of its users for a few years now, but you had to do a little digging to get to it. First you could find it in the Health app on the iPhone and more recently under the Trends tab in the Fitness app. But even if you did happen upon this number, Apple provided little context about what it meant for you, plus it required you to complete a certain number of outdoor runs or brisk walks to populate.
A high cardio fitness score on the Health App.
With the latest iOS 14.3 update, the Fitness app will now categorize that VO2 max number in reference to your fitness level: high, above average, below average or low. This is similar to what other trackers like Fitbit and Garmin offer on some of their devices, but the Apple Watch will also give you the option to receive a notification on your watch if your cardio fitness score dips into the low range.
You won't even have to break a sweat to get your cardio fitness score. VO2 max on the Apple Watch can be calculated as you're moving normally about your day and not necessarily during a strenuous exercise, as long as it gets your heart pumping. It's also backwards compatible, meaning you'll be able to see your score immediately after updating the watch if you've already had VO2 max information on the app.
The low cardio fitness alert on the Apple Watch.
Apple anticipates that measuring and rating VO2 max may help motivate you to improve your fitness, in the same way that seeing daily steps or calorie burn on your watch can encourage you to move more.
"The ability to measure something for some people can be really motivating, to see how it changes," says Dr. Sumbul Desai, Apple's vice president of health. "In that way, cardio fitness can be a really useful measure for everyone, not necessarily only someone who runs marathons."
The more you know, the more you can improve
Measuring your VO2 Max used to require a lab test. Patients were put on a treadmill or stationary bike while hooked up to a heart rate monitor and a mask measured oxygen exchange. Having this metric readily available on your wrist or phone without having to step foot in a doctor's office can help users set measurable fitness goals over time.
"The really special thing about VO2 max is that you can actually do something about it. And the key to that is in exercising more and in increasing your intensity, you'll actually see an improvement," says Dr. Desai.
Adding a couple of extra steps a day isn't going to move the needle when it comes to your cardio fitness or VO2 max. Improving your cardio fitness rating will require pushing yourself during exercise over a longer period of time, whatever that means to you. If you're on the fitter side, this may be through high-intensity interval training (aka HIIT), but if you're just getting started it could be anything that gets your heart rate up, like going for a brisk walk.
Capturing VO2 max data on your wrist may be valuable to help understand your fitness levels, but as with any wearable, there are caveats. "It seems unlikely that accelerometers and PPG sensors alone [in the Apple Watch] can capture all of the nuances of medical tests and therefore should not be seen as replacements," says Dr. Geoff Tison, a cardiologist and assistant professor of cardiology at University of California in San Francisco. "But if it is well validated and with low enough error, the ability to passively monitor these metrics in large numbers of people without complex equipment could be valuable."
CNET hasn't tested the VO2 max on the Apple Watch against the lab equivalent for accuracy and this metric should not be used for diagnostic purposes. As always, please consult with a physician or other qualified health provider about any health-related issues or health objectives before starting an exercise program.
