What does your VO2 max number mean? A guide to fitness and healthy aging

There are plenty of numbers we use to keep tabs on our health. Blood pressure. Cholesterol. Resting heart rate. Daily steps.

Lately, another number has been getting more attention: VO2 max.

Unless you’re already familiar with the term, seeing a VO2 max of 28, 37, or 52 probably leaves you with more questions than answers.

“Your VO2 max is a representation of your engine,” says Tiffany Gust, MS, NBC-HWC, an exercise physiologist with Intermountain Sports Performance who developed its high-performance aging program.

Gust knows the athlete side of VO2 max well. She has completed more than 175 triathlons, including 24 Ironman races. But in her work, VO2 max isn’t only about helping athletes go faster or farther. It’s also about helping people maintain the fitness they need to stay active throughout life.

Whether that means competing in a race, hiking with friends, keeping up with your grandkids, or simply climbing a flight of stairs comfortably, your “engine” has a lot to do with what your body can keep doing as you age.

What is VO2 max?

VO2 max measures your body’s ability to take in oxygen, transport it through your body, and use it for energy during exercise.

Your lungs bring oxygen in. Your heart and blood vessels move it where it needs to go. Your muscles use it to keep you moving. VO2 max helps show how well that whole system works together.

If you’ve never seen a VO2 max number before, here’s a general sense of the range. Results are measured in milliliters of oxygen per kilogram of body weight per minute, or mL/kg/min.

As a broad frame of reference:

• 20s: Common among less-active adults and many older adults
• 30s and 40s: Common among many generally active adults
• 50s and 60s: A sign of high aerobic fitness for many adults
• 60s, 70s and above: Often seen in highly trained endurance athletes

These aren’t grades or universal targets. Age, sex, activity level, health, and other factors all affect VO2 max. That’s why a result is usually compared with reference values for people of a similar age and sex – and with your own results over time.

“VO2 max can be a test that can be really utilized for anyone,” Gust says.

For someone who is less active, testing can provide a starting point. For a recreational exerciser, it can help track changes in fitness. And as we age, cardiorespiratory fitness – the health and function of your heart, lungs, and blood vessels during activity – becomes an important part of staying healthy and active.

Why does VO2 max matter as you age?

Some loss of cardiovascular capacity happens naturally with age. Gust explains that VO2 max can decline significantly over the decades, especially in people who are sedentary.

Regular cardio can help your heart, lungs, blood vessels, and muscles keep working efficiently. Strength training matters, too, because we also tend to lose muscle as we age, a process known as sarcopenia.

Together, cardio and strength training can help preserve the fitness you use in everyday life – whether you’re climbing stairs, walking through an airport with your luggage, working in the yard, traveling, or playing with your grandkids.

Can your smartwatch really measure VO2 max?

Many fitness watches now provide an estimated VO2 max, but there’s an important word in that sentence: estimated.

A smartwatch doesn’t measure VO2 max the same way a laboratory does. Different devices can even give the same person different results. Gust sees this herself because she regularly wears devices from two different brands.

What wearables can do well is help you notice patterns.

Instead of worrying about whether your VO2 max score changed by a point, look at what has been happening over weeks or months. Is your estimated fitness gradually improving? Has it dropped unexpectedly even though your activity hasn’t changed?

Gust has seen how those trends can sometimes prompt an important conversation with a healthcare provider.

She also experienced it herself. While training indoors for an Ironman, she noticed her heart rate had climbed above 200 beats per minute – far outside what was normal for her. When another monitor showed the same thing, she contacted her physician and shared the data from her Garmin. Further evaluation revealed atrial fibrillation, or AFib, an irregular heart rhythm.

A watch can’t diagnose a heart condition. But a persistent change that doesn’t make sense may be worth discussing with your healthcare provider, especially if you also notice symptoms or changes in how you feel.

How is VO2 max actually tested?

A clinical or laboratory test provides a more accurate VO2 max measurement. During the test, you exercise while wearing a mask that measures the gases you breathe in and out as the exercise becomes progressively harder.

Testing can be matched to your activity. A runner or walker may use a treadmill, while a cyclist may use a stationary bike. Sports performance centers and some medical or university fitness programs offer testing.

For most people, however, you don’t need a VO2 max test before you can start improving your fitness.

How can you improve your VO2 max?

Start with something decidedly less high-tech: consistency.

Being active regularly does more for cardiovascular fitness than an occasional hard workout followed by long stretches of inactivity.

From there, Gust recommends gradually challenging your cardiovascular system.

If you usually walk for 30 minutes, for example, you might slowly add another five or 10 minutes as your fitness improves. You can also include periods when you pick up the pace, followed by easier recovery.

High-intensity interval training (HIIT) uses this harder-effort, recovery pattern. But “high intensity” is personal. Someone beginning an exercise program may work harder for only 20 or 30 seconds before taking a longer recovery.

If you have a medical condition, concerning symptoms, or questions about what level of exercise is safe for you, talk with your healthcare provider before significantly increasing your activity.

Do you need a high VO2 max to be healthy?

There’s no need to turn VO2 max into another number you have to perfect. What matters is building cardiovascular fitness from your own starting point and paying attention to changes over time.

Numbers can provide useful information, but so can everyday life. Notice how you feel during activity, how well you recover, and whether activities that used to feel easy suddenly become difficult.

You don’t need to be training for an Ironman to invest in your fitness. At Intermountain Health, sports performance and healthcare experts can help you understand your cardiovascular fitness and build an approach that fits your health and goals.

For more information about fitness testing, training, and programs designed to help you stay active at every age, visit the Intermountain Health Performance Health and Sports Training page.