Trackers, Treadmills, & Masks: Measuring VO2 Max - Part 2 of the VO2 Max Series

Trackers, Treadmills, & Masks: Measuring VO2 Max - Part 2 of the VO2 Max Series

Hillary Lin, MD

By 

Hillary Lin, MD

Published 

Mar 29, 2024

We last discussed why VO2 max is all the rage for people who care about health and longevity. For those of you who didn't read the already very concise last post, the tldr is that VO2 max is a metric of your cardiovascular fitness that can be measured over time. Cardiovascular fitness (heart health) is the part of our longevity equation we can most control and, according to many studies with gigantic groups of subjects, is inversely correlated to all causes of mortality.

Yes I put a cute animal gif here that is only vaguely related to the topic (heart fitness) to draw in your attention and focus.

But the obvious question now is…

How do I know what my VO2 max is?

Obvious follow-up question is how to test your cardiovascular fitness. Luckily, there are about a dozen ways to do this. However, every single test has flaws.

I just completed three cardiovascular fitness tests in the last two weeks. While I am a dedicated writer, it was not actually because of some investigative journalist itch that I did this. I scheduled the first VO2 max test because I wanted to check my Apple Watch's estimate against the gold standard. The second was actually an ECG stress test ordered by my cardiologist (I'm undergoing a cardiac workup given a genetically high cholesterol level). The final VO2 max test was done because my friends are starting a testing company in NYC and I thought, why not? More data, more better.

Note: This is a long but skimmable post, meant to be a practical reference/guide. You can skip to the type of testing you're most interested in and read in greater detail, or skim through to get a general idea of what might be feasible for you!

In this post:
• The most accurate way to test your VO2 max.
• The freest way to test your VO2 max.
• How to test your VO2 max if you’re a couch potato.
• Using your wearables to test your VO2 max.

Laboratory Testing - Direct Measurement (Gold Standard)

More accurate, less convenient, kinda expensive

This type of testing is how my VO2 max testing was conducted. It involves a trained professional fitting you with a mask to detect your oxygen intake (directly measuring your VO2 max) as you exercise at higher and higher intensity. Typically, this is done on a treadmill or stationary bike, although variations exist for other types of exercise like rowing or even outdoor running (where a team follows you with machinery on a golf cart!).

The name direct measurement comes from a sensor in your facial mask that directly measures your VO2 max throughout the test.

This is what a typical VO2 max direct measurement setup looks like. Lots of tubing going on, plus a kind of uncomfortable facial mask.

Luckily, we now have bluetooth-connected masks so we don’t need quite as large of a set up in most cases, although you may still find the tubed set-ups in most testing facilities.

The price of a test, for those of you curious, is anywhere from $75-300 depending on where you live, and whether you go to a research center or a fitness setup. Or you could buy an analyzer for about $6000 and just test yourself repeatedly at your gym. 😂

Field Testing - Indirect Measurement

Less accurate, self-test possible

There are a number of ways to estimate VO2 max that are free to self-conduct! The caveat is, these are more estimates given a lower general accuracy.

The Cooper Test:

This test is the easiest to do on your own. The steps involved are:

  1. Setup: Prepare a timing device (like a stopwatch) to accurately measure a duration of 12 minutes. Choose a level and measurable course for the test, such as a standard 400-meter track, or opt for a treadmill if preferred. Make sure you’re wearing running attire and shoes.
  2. Warm-Up: Engage in a comprehensive warm-up session approximately 10 minutes before starting the test. This should include dynamic stretching and a some light jogging to prepare your body.
  3. Test Execution: Aim to run at a consistent and sustainable pace throughout the 12-minute period, avoiding starting too rapidly to prevent premature fatigue.
  4. Distance Measurement and Cool Down: Upon completion of the 12 minutes, record the total distance covered. Follow up the test with a cool-down phase, consisting of a gentle walk or jog for about 5 minutes to facilitate recovery.
  5. VO2 Max Calculation: Utilize the distance you achieved during the test to estimate your VO2 max with the provided formulas, depending on the measurement unit of the distance covered:

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VO2 max = (22.351 × kilometers) − 11.288

OR (for miles)

VO2 max = (35.97 × miles) - 11.29

There are various formulas for estimating VO2 max from the Cooper Test, and the one provided is a common example. The exact formula may vary based on the source.

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The Beep Test (or Bleep Test):

This is also known as the Multi-Stage Fitness Test, PACER Test (Progressive Aerobic Cardiovascular Endurance Run), or 20m Shuttle Run Test. It involves running back and forth between two lines, 20 meters apart, at an increasing speed dictated by beeps from a recording. The beeps will get closer together in timing as the test goes on. The level reached before failing to keep up with the beeps can be converted into a VO2 max estimate.

This is a beep test audio file (made by Australians, so the beeps may have an Australian accent 🤔).

The steps to conduct the Beep Test are as follows (note that warm up and cool down as described above is recommended for all VO2 max testing):

  1. Setup: Locate or create a flat, straight course that measures 20 meters in length. Place visible markers at each end to clearly indicate the start and end points. Position yourself at one end of the 20-meter track.
  2. Test Execution: Initiate the Beep Test audio track. The initial signal will typically consist of a unique series of beeps (often a triple beep) to signify the start. Upon hearing the starting signal, start running towards the marker at the opposite end.
  3. Marker Touch: Upon reaching the far marker, lightly touch it with either your hand or foot. If the audio cue for the next interval has yet to sound, remain at the marker. Proceed to run back to the starting marker only upon hearing the next beep.
  4. Pace Increase: The test is structured in levels, with the pace (interval between beeps) incrementally increasing at each subsequent level. The goal is to reach the opposite marker before the sounding of the next beep.
  5. Test Conclusion: The test is considered complete when you fail to reach the marker before the beep on two consecutive attempts.
  6. VO2 Max Estimation: To estimate your VO2 max, apply the level reached in the test to the following formula:

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VO2 max = 5.857 × level + 29.4

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There are also some tables that can help you determine a VO2 max from the level at a glance, such as the one above.

The 1.5 Mile (2.4 km) Run Test:

This test just requires you to run 1.5 miles as fast as possible, with VO2 max estimated based on the completion time (see calculator here and table/equation below).

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VO2 max = 88.02 − (0.1656 × body weight in kg) − (2.76 × time in minutes) + (3.716 × gender index)

Gender index = 1 for males, and 0 for females.

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Helpful note: A standard track is 400 meters per lap, so 1.5 miles is approximately 6 laps plus an additional 9 meters. If you’re an urbanite like me though, just stick to a treadmill.

There are numerous similar tests for swimming, ellipticals, etc. that work similarly to estimate your cardiorespiratory fitness. This is a website with (supposedly) all the fitness tests.

Submaximal Exercise Tests

For those with lower baseline fitness or conditions preventing high exertion

These are similar types of tests adapted for people who are starting from a deconditioned state due to age, disease, injury, or simply lack of exercise (very normal in the United States!). There are many variations of submaximal exercise tests, all essentially accommodating the individual’s specific needs to lower testing intensity. One example is the following:

The Bruce Submaximal Treatment Test

Note: For any individual with any medical concerns or conditions, it is especially important to have medical supervision to ensure testing is done safely.

  1. Start the Test: Begin the test with the treadmill set to the initial speed and incline of the Bruce Protocol (1.7 mph at a 10% incline).
  2. Progression: Every three minutes, increase the speed and incline according to the Bruce Protocol stages. The submaximal version of the test typically progresses through these stages at a more conservative pace or stops when a submaximal level of exertion is reached. For example, the progression may go as follows:
    1. Stage 1: 1.7 mph at a 10% incline
    2. Stage 2: 2.5 mph at a 12% incline
    3. Stage 3: 3.4 mph at a 14% incline, and so on.
  3. Monitoring: Continuously monitor your heart rate and subjective level of exertion using a scale like the Borg Rating of Perceived Exertion (RPE).
  4. Termination Criteria: The test is stopped when you reach a predetermined predetermined submaximal heart rate (e.g., 70-85% of the estimated maximum heart rate), or show signs of fatigue, or simply want to stop. Unlike the maximal test, the submaximal version does not require you to reach volitional exhaustion.
  5. VO2 max Estimation: The estimate of VO2 max will be pretty approximate given the submaximal nature of this test, but a simple formula is the following:

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VO2 max = (HR exercise / HR max​) × VO2 at test workload

HR max (theoretical maximum heart rate) is commonly estimated by 220 minus age for men, or 226 minus age for women (although there are many debates on the best formula).

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Fun Fact: Bruce and colleagues developed the cardiac stress test that I (and many others) completed for my cardiac workup! The main purpose of a stress test is to evaluate electric activity and thus heart function while completing progressively harder physical workloads. This is different from a VO2 max test which is really looking at maximum capability of your cardiorespiratory system.

Fitness Trackers and Smartphone Apps

Most convenient, pretty inaccurate, but good enough

If you’re like me, you might already be wearing an Apple Watch or similar health and fitness tracker all the time. Turns out, they have VO2 max algorithms in most fitness wearables. But how accurate are they?

There aren’t many studies comparing everyday wearables against gold standard direct measurement tests for VO2 max (plus, new versions come out each year), but this somewhat outdated 2021 study showed that “wearables using resting condition information in their algorithms significantly overestimated VO2max, while devices using exercise-based information in their algorithms showed a lower systematic and random error.”

This kind of translates to, “Wearables are kind of inaccurate but the ones using exercise (versus resting) data are better.” Apple itself notes that its measurements are best calibrated for outdoor runs, which never happen for indoor exercise fanatics like myself (I don't really like sun and wind, what can I say?).

Apple's own study (for the watchOS 7) in 2021 showed a rough correlation between the Apple Watch VO2 Max and validated direct measurement. Still, you can see how individuals' measurements were all over the place, with some differing by over 10 ml/kg/min.

First, you have to turn it on!

This article provides step-by-step instructions for turning on VO2 max measurement capabilities on the Apple Watch, Garmin, and Fitbit. To trigger the measurement on any wearable, you'll need to exercise for some length of time (such as running for 10 minutes). Some might gather measurements with more passive movement, but as the study above states, such results will be less accurate.

As machine learning methods have improved the wearables’ algorithms, I think watches are an acceptable and easy way to track cardiorespiratory fitness progress over time. My practice is to use my watch as my regular VO2 max measurement device, with an annual check via direct measurement.

Next up - How do I improve my VO2 max?

The next post will involve how you can work on improving your cardiovascular/cardiorespiratory fitness, or your VO2 max.

What I’ll aim to cover are strategies that a person can use no matter your starting point. Even if you literally spend 90% of your life lying or sitting down, there are ways to improve your VO2 max. In fact, from a relative standpoint, it’ll be a lot easier to improve your VO2 max the more sedentary you are. 😂

My challenge to you now is to put on your calendar a time and date when you will test your VO2 max. As you can see from all the methods described above, this can be done by yourself for $0 cost!

This is one of the foundational stepping stones to determining the rest of your health/life, with little exaggeration. You only need a watch, sneakers, a place to run (or bike), and 12 minutes. The best part - no one has to know your result except you if you want!

Until next time…Cheers to your health,

Hillary Lin, MD

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