If you’re part of the online running community, you’ve probably seen runners flexing their VO2 max numbers. If you wear a running watch, you’ve probably also aware of your own VO2 max—maybe you’ve been proud (some devices equate a higher VO2 max with a lower fitness age!) or maybe you’ve just been confused as to what this number even means.
VO2 max has long been considered one of the gold standards for measuring cardio fitness. That said, getting a real measurement has been inaccessible to a lot of runners for just as long, because it usually involves going to some kind of sports performance lab for a test that isn’t cheap. But here’s the good news: You don’t need a lab to estimate your VO2 max. You can get a pretty good sense of where your fitness stands without any fancy tech, right at home. Here’s what to know.
What Your VO2 Max Number Means
This biometric has become a fitness buzzword in recent years. It measures, in milliliters of oxygen consumed per kilogram of bodyweight per minute, how much oxygen your body can use during exercise.
What does that really mean? “It’s a measurement of the capacity of your cardiovascular and respiratory system while you carry out strenuous exercise,” explains Carson Gantzer, C.S.C.S., a performance physiologist at Human Powered Health in Scottsdale, Arizona. “The more oxygen you’re able to intake, the better all of your systems are functioning and operating.”
A higher VO2 max is associated not just with better fitness, but also improved overall health. In 2016, the American Heart Association issued a statement saying that VO2 max should be considered a vital sign, and a meta-analysis published in the International Journal of Exercise Science that same year called it “the strongest predictor of cardiovascular and all-cause mortality.”
“Essentially, the higher your VO2 max is, the better your healthspan and longer your lifespan,” says Gantzer.
For runners, VO2 max is a big indicator of your aerobic fitness, which plays a huge role in how fast, how long, and how hard you can run. “I like to think about it as the size of your aerobic engine,” says Jonah Rosner, a sports scientist focusing on runners. The more efficiently your body can deliver oxygen to your muscles so they can produce energy, the easier it will be to sustain a certain pace.
How to Determine VO2 Max
Traditional VO2 max tests are done on a treadmill in performance labs, physical therapy facilities, medical centers, or even some gyms. The test is a graded one, in that it starts at a low-intensity effort and increases by a fixed amount—by upping the speed of the treadmill or increasing the incline—at regular time intervals until exhaustion, usually within eight to twelve minutes, says Rosner. (You’ll do a separate warmup before the test.)
During the test, you wear a mask that’s connected to something called a metabolic cart, a device that “measures the amount of oxygen you’re consuming and carbon dioxide you’re producing to indirectly calculate energy expenditure—this process is called indirect calorimetry,” explains Rosner. As your exercise intensity increases, so does your body’s demand for oxygen. “You reach your VO2 max when the amount of oxygen that you’re using stabilizes, even if you’ve increased the speed or intensity of the exercise,” he says.
This kind of test is known as the direct method of determining VO2 max, explains Gantzer, but it’s not always convenient or affordable for runners. That doesn’t mean you can’t get a good estimate of this fitness metric, though.
There are indirect methods for estimating VO2 max that you can DIY without a mask or a technician or even a treadmill. “These are considered ‘indirect’ because there is no direct measurement of any oxygen or gases,” says Gantzer. “Instead, you’re looking at metrics like distance covered or time trial performance.”
Many fitness watches estimate your VO2 max based on heart rate data and exercise data, like pace.
3 Ways to Test Your VO2 Max at Home
1. The Cooper Test
The Cooper Test dates back to the late 1960s, and was proven to closely correlate with laboratory-determined oxygen-consumption data.
It’s a super simple field test; all you really need is a stopwatch and, ideally, a 400-meter track (though you can do it anywhere, as long as you’ll be able to easily calculate your total distance).
After a short warmup, run or walk as fast as you can in 12 minutes. Then, you’ll calculate your VO2 max using the formula below. “Essentially, the more distance an individual can cover, the higher your predicted VO2 max will be,” says Rosner.
Formula: VO2 max = (35.97 x your distance in miles) – 11.29
2. The Rockport Walk Test
Another straightforward field test—but with a few more steps and a little more math—the Rockport Walking Test was shown to be a valid predictor of VO2 max compared to a running test in a 2011 study published in Military Medicine.
Similar to the Cooper Test, you’ll do a short warmup at an easy walking pace. Then, you’ll walk as fast as you can (no jogging!) for one mile. At the end, record your time in decimals (i.e. 14.5 minutes for 14:30) and record your heart rate immediately (you can count your heartbeat for 15 seconds and multiply by 4) or check your smartwatch. You’ll also need to know your weight in pounds.
Formula: VO2 max = 132.853 – (0.0769 x your weight in pounds) – (0.3877 x your age) + (6.315 x 1 if you are male or 0 if you are female) – (3.2649 x your walking time) – (0.1565 x your heart rate at the end of the test)
3. Heart Rate Ratio Method
There’s a very simple equation you can use to calculate your VO2 max, according to research published in the early 2000s. But first you’ll need to calculate your resting heart rate and your heart rate max.
You should calculate your resting heart rate right after you wake up, by placing your index and middle fingers on your carotid (neck) or radial (wrist) pulse and counting the number of times your heart beats in one minute (you can also count for 30 seconds and multiply that number by two, or 15 seconds and multiply by four).
There are several options for calculating max heart rate, the most simple of which is to subtract your age from 220 (it’s not always accurate, but gives an estimation). Then, you’ll use the below equation to estimate VO2 max.
Formula: VO2 max = 15 x (max heart rate/resting heart rate)
What to Do With Your VO2 Max Stats
Like most trackable biometrics, one of the best reasons for measuring your VO2 max is to monitor your fitness progression. “As you become more aerobically fit, this number will continue to increase, and you’ll see your big block of zone 2 running or your Norwegian 4x4s are actually helping you to become a healthier and faster runner!” says Gantzer.
Measuring your VO2 max can also help with determining your training zones, says Rosney, including your heart rate zones and anaerobic threshold. A wearable can estimate those, but because it uses data that may or may not be accurate (like your heart rate), your zones and recommended paces may be slightly off, which could negatively affect your training—i.e. you’re running your easy efforts too hard, or you’re not pushing the pace enough in your intervals.
That said, there are some caveats with indirect testing, during which you’ll get an estimate of your VO2 max. “If you choose to measure your VO2 max outside of a lab, at a gym, or on a track, you should take your results with a grain of salt,” says Gantzer. “While indirect methods can be more affordable and completed on demand, they present numerous opportunities for skewed results because of poor pacing, lack of applicability of a certain test protocol to a certain population, inconsistent heart rate monitoring equipment reliability and validity, and lack of control of testing conditions and environment.”
Same goes for the estimated VO2 max on your watch. “While wearables and their algorithms are becoming better at estimating VO2 max values, they still have limitations due to their hardware,” says Gantzer. These devices aren’t always 100 percent accurate, and “if you’re feeding inaccurate information into an algorithm, you’re going to get an inaccurate result,” he adds.
Bottom line: “I would argue that most runners don’t need lab-based VO2 max testing,” says Rosner. It can be a valuable tool, but the trend is more important than a singular number. So keep an eye on your stats over time, and retest with the same method. “If you do a workout and then train for a few weeks and do the same workout, but it feels easier and you’re going faster, that’s just as valuable information as a specific number.”
Instead of fixating on any one data point, focus on what matters most: consistent, smart training.
Ashley Mateo is a writer, editor, and UESCA- and RRCA-certified running coach who has contributed to Runner’s World, Bicycling, Women’s Health, Health, Shape, Self, and more. She’ll go anywhere in the world once—even if it’s just for a good story. Also into: good pizza, good beer, and good photos.
