How to Evaluate Your VO₂ Max - An Important Longevity Marker - Part 2
Practical guide to assessing your VO2 max
This is Part 2 of a three-part series on VO2 max. Last time I wrote about the definition of this marker and its significance for our health and longevity (Link to the article). Today, I intend to describe the available methods for estimating your VO2 max. In the third one, I will discuss training methods likely to improve your aerobic fitness and, in turn, your VO2 max.
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If I had to pick one fitness number that best predicts not just how long you’ll live, but how well and independently, it would be your VO₂ max. Recent research shows that cardiorespiratory fitness, usually measured as VO₂ max, is one of the strongest predictors of overall mortality and heart problems, even more so than traditional risk factors like smoking, diabetes, or high blood pressure.
In this article, I’ll explain how VO₂ max is measured, the different ways you can estimate it, starting from high-tech labs to simple questionnaires and watches, and how accurate each method is.
My goal is to give you a general idea so you can choose the best approach for your needs and avoid being misled by numbers that seem precise but are not.
However, remember that safety should be your number one priority. Not everybody is fit enough to run at a high heart rate for 12 minutes or for an hour. For some of you, just knowing how far you can walk in 10 minutes without running out of breath, or how many flights of stairs you can climb without a rest, may be the best and safest assessment.
Before conducting any intense tests without supervision, you should consult your doctor to determine if it is advisable for you.
What VO₂ Max Actually Measures
VO₂ max is the highest rate at which your body can take in, move, and use oxygen during intense exercise. It shows how well your heart, lungs, blood vessels, and muscles work together when you are working hard. VO₂ max is measured in millilitres of oxygen per kilogram of body weight per minute (mL/kg/min) or, sometimes, in METs. One MET equals 3.5 mL/kg/min.
The Gold Standard: Lab VO₂ Max Test (CPET)
If you want the most accurate number, there is only one proper gold standard: a maximal cardiopulmonary exercise test (CPET) with gas analysis.
What it looks like
You exercise on a treadmill or cycle ergometer.
You wear a mask connected to a device that measures how much oxygen you inhale and how much carbon dioxide you exhale, breath by breath.
The workload increases gradually until you reach voluntary exhaustion (or clear physiological/clinical stopping criteria).
Accuracy and pros/cons
Accuracy: test–retest variation is about 3–5%, with measurement error around ±2–3 mL/kg/min.
Pros:
Most accurate reflection of cardiorespiratory fitness.
Provides rich data: heart rate and ventilatory thresholds, blood pressure response, rhythm, and sometimes oxygen saturation.
Critical for risk stratification in heart disease and for fine‑tuning training in serious athletes.
Cons:
Expensive equipment and trained staff are required.
Maximal effort is demanding and not suitable for everyone.
Typically, only available in sports labs, hospital systems, or specialized clinics.
Who should consider it?
If you’re over 50 with cardiovascular risk factors, known heart disease, or you want precise, physician‑supervised data to guide your training and risk assessment, a formal CPET is worth considering. For most others, reasonable estimates described below are usually sufficient.
Sub-maximal Tests: Safer, Simpler, “Good Enough” for Most People
Because maximal testing requires significant resources, several submaximal tests have been developed. These tests stop before you reach exhaustion and estimate VO₂ max based on your heart rate and performance.
These tests are invaluable for people over 50, since safety and practicality are essential.
1. Åstrand - Ryhming Cycle Test
This is a classic 6-minute cycling test at a steady workload that raises your heart rate into a target zone, typically 125-170 bpm. Once your heart rate is constant, your VO₂ max is estimated using a chart that factors in your age-predicted maximum heart rate. In terms of accuracy, this test shows correlations with lab-measured VO₂ max of 0.76-0.90, with a standard error of about 5.7-6.7 mL/kg/min.
Pros: Short, relatively comfortable, widely used in labs and rehab; safer than maximal testing.
Cons: Needs a properly calibrated cycle ergometer.
2. Rockport 1‑Mile Walk Test
You walk one mile as fast as you can, ideally on a track, and record your time and your heart rate at the end. An equation that uses your age, sex, body weight, time, and heart rate estimates your VO₂ max.
Accuracy: Original validation showed a correlation of 0.88 with VO₂ max and a standard error of about 5.0 mL/kg/min.
Pros: Minimal equipment (a watch and heart rate monitor), reasonably safe for older or sedentary individuals, easily repeated.
Cons: Weather, terrain, and how you pace yourself can affect the results. You also need to walk as fast as you can for the most accurate number.
3. Cooper Run Tests or 1.5-mile test
These involve either running as far as possible in 12 minutes or completing 1.5 miles as fast as possible
Accuracy:
1.5‑mile/12‑minute tests correlate around 0.90 with lab VO₂ max in reasonably fit populations.
Pros: Simple, no equipment beyond a track, watch
Cons: These tests require you to give your maximum effort, not just a moderate one. They are not the best choice for many people over 50, especially if you are out of shape or have joint or heart problems.
Non‑Exercise Prediction: Surprisingly Good (When Done Right)
One interesting development in the past 20 years is that VO₂ max can now be estimated quite accurately without any exercise. These methods use information like your age, body type, resting heart rate, and your own reports of your physical ability and activity.
The Bradshaw Model: A High‑Accuracy Questionnaire
The Bradshaw non‑exercise regression model uses:
Age, Sex, BMI
A Perceived Functional Ability (PFA) questionnaire (how fast you think you could cover 1 mile and 3 miles
A Physical Activity Rating (PA‑R) for the past 6 months.
In validation, this model correlated 0.93 with lab VO₂ max and had a standard error of around 3.45 mL/kg/min, comparable to many maximal exercise protocols.
In other words, a well-designed questionnaire and some basic body measurements can estimate your actual VO₂ max within about 8 to 10%, as long as you answer honestly and understand the questions.
AI Models for Older Adults and Machine Learning
More recent work in adults aged 50–96 has used machine‑learned models incorporating age, gait speed, 400 m walk performance, grip strength, and other functional measures. These models yield standard errors of 2.8–4.2 mL/kg/min and correlations of ~0.90 with measured VO₂ max.
The downside is that these models are more complex, require more data, and are harder to understand. Still, they are promising tools for extensive studies and could help with clinical decisions in the future.
How this helps you: As a reader, you can use trusted online tools based on these equations to quickly estimate your VO₂ max. If you are a clinician, these models are helpful for assessing risk in older adults when exercise testing is impractical.
Smartwatch VO₂ Max: How Much Can You Trust It?
Many people now have a Garmin, Apple Watch, Polar, or Fitbit that shows a VO₂ max number. These devices use their own algorithms that look at your heart rate and pace (or power) during runs, walks, or rides, along with your age, sex, and weight.
Garmin and Polar
Garmin and Polar have been studied more than most. Validation work has shown mean errors of 5–7%, with many users’ estimates within about 3.5 mL/kg/min of the lab‑measured VO₂ max when the device has good data and a correct maximal heart rate setting. Correlations with true VO₂ max can reach ~0.90 in active individuals.
In practice, this is quite good and comparable to reliable field tests, as long as you regularly record high-quality workouts and your watch accurately reflects your maximum heart rate.
Apple Watch
More recent studies on Apple Watch VO₂ max estimation suggest larger errors:
Mean absolute error around 6–7 mL/kg/min.
Mean percentage error in the range of 13–16%.
Tends to underestimate VO₂ max on average, with fairly wide individual variability.
So while changes over time, whether up or down, can be helpful, I would not treat an Apple Watch VO₂ max as a precise clinical measurement.
Fitbit and Others
Fitbit and some other consumer devices usually do not perform as well. They often overestimate VO₂ max and have larger error margins in studies.
How to use numbers from wearable devices wisely?
Use these numbers to spot trends, not as exact measurements.
Be especially careful if you have irregular heart rhythms, take medications that control your heart rate, or mostly do short or low-intensity workouts. These situations can make the numbers less accurate.
If your Garmin or Polar estimate is close to a lab test or a good field test, you can use it to track your cardiorespiratory fitness over time and see whether it is improving, staying the same, or declining.
Which Method Should You Choose?
For people over 50, the best method depends on your health, your goals, and how much testing you are comfortable with.
If you have a significant heart risk or known heart disease, I recommend supervised testing first. A CPET in a clinic or sports cardiology setting gives you your VO₂ max, ventilatory thresholds, and a safety check all in one visit. This is the most informative choice when your risk is higher. If this is not available or needed, a submaximal Åstrand cycle test in a monitored setting is a safer alternative that still gives a good estimate.
If you are generally healthy and just want a reliable, practical number, a Rockport 1-mile walk test or a well-run treadmill test is usually enough.
If you would rather not test at all, or cannot because of joint or access issues, a good non-exercise calculator based on the Bradshaw or similar model is still very helpful. It usually gets within about 8 to 10% of your true VO₂ max if you answer honestly.
If you already use a device, I treat Garmin and Polar numbers as reasonable estimates and focus on how they change over time. Apple Watch and Fitbit numbers are more useful for spotting trends but are not accurate enough for detailed training or clinical decisions on their own.
Summary
VO₂ max is one of the most potent and changeable predictors of how long you’ll live and how well you will be. In my opinion, knowing your VO2 max is essential for people over 50. It should be as important as knowing your blood pressure, cholesterol and hemoglobin A1C.
The gold standard is a lab-based cardiopulmonary exercise test with gas analysis. Still, sub-maximal cycle, walk and run tests, well-validated non-exercise equations, and high-quality wearables can all provide helpful information.
If you are a health-conscious reader, the best approach is to pick the method that fits your risk, resources, and comfort, and then track your VO₂ max or its estimate over time. What matters most is whether your number goes up, stays the same, or goes down. Even a slight improvement can lower your long-term risk, and just keeping your level steady as you age is a win.
If you want to focus on one number for your longevity and wellness, VO₂ max is a great choice.
Next week, in Part 3, I will discuss training methods known to improve your aerobic fitness and VO2 max.