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VO₂MaxUnderstand, measure and improve your cardiorespiratory fitness

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How to measure VO₂Max

VO₂Max can be measured directly through respiratory gas analysis or estimated from exercise, heart rate, and other information. Here are the methods described by Japan’s Ministry of Health, Labour and Welfare (MHLW), and the features of each.

Visual guide

Direct measurements and estimates take different paths

Healthcare and research institutions

Measure through respiratory gas analysis

  1. Exercise with an increasing workload

    Use a cycle ergometer or treadmill.

  2. Analyze exhaled air

    Use respiratory gas analysis equipment.

  3. Measure oxygen uptake

The inputs depend on the method

Estimate from exercise or heart rate

  1. Collect exercise or heart rate information

    Workload, test results, speed, heart rate, and other inputs.

  2. Calculate using a formula or device

    Submaximal tests, field tests, or a smartwatch.

  3. Obtain an estimated VO₂Max

The VO₂Max calculator based on resting heart rate on this site also produces an estimate. Check the study population and limitations

This diagram compares methods. Direct measurement requires equipment and trained staff. Estimates have errors and are not diagnoses.

1. Direct measurement: exercise testing with respiratory gas analysis

Exercise on a cycle ergometer or treadmill with a gradually increasing workload until exhaustion. Exhaled air is analyzed to measure oxygen uptake.

This measures oxygen uptake directly. It requires expensive equipment and trained staff, so it is not a readily available self-test.

Where: Healthcare and research institutions

2. Submaximal exercise testing

Exercise at two or three workloads below exhaustion. VO₂Max is estimated from the relationship between workload and heart rate, together with maximum heart rate.

Used in settings such as fitness clubs.

Where: Fitness clubs and similar facilities

3. Field tests

VO₂Max is estimated from results such as a 20 m shuttle run or a six-minute walk.

These methods are used in the Japan Sports Agency’s physical fitness surveys.

Where: Schools and fitness testing venues

4. Wearable devices

Methods vary by device and feature. Some use outdoor exercise GPS, speed and heart rate; others use resting heart rate and other information.

An increasingly common method. The value is an estimate, and individual errors can be substantial.

Where: A smartwatch and its app

Japan’s standard questionnaire for specific health checkups also asks about walking speed as a simple assessment of cardiorespiratory fitness (MHLW, 2023).

What you can do on this site

  • Use a smartwatch value to support exercise: Our smartwatch guide takes you from finding the value to recording conditions, choosing exercise, staying consistent, and reviewing your routine.
  • Find your smartwatch’s value: See how to view VO₂Max on a smartwatch and phone for where to look and the conditions needed on Apple Watch, Fitbit and Pixel Watch, Galaxy Watch, and Garmin.
  • Estimate from resting heart rate: If you do not have a smartwatch, our tool uses the ratio of maximum to resting heart rate (Uth et al., 2004). The original study involved 46 well-trained men. With age-predicted maximum heart rate, the standard error of estimate was about 4.7 mL/kg/min; this does not guarantee that an individual’s error will fall within that range. The authors called for further validation in women and people with different training backgrounds. Open the estimation tool
  • Compare with age-based values: Compare a smartwatch value or another estimate with the Japanese age-group averages and reference values presented by MHLW. Open the comparison tool
  • Understand a low cardio fitness notification: Distinguish the criteria described in Apple’s 2021 technical paper from current official guidance, and learn about estimation errors and differences from the MHLW tables. Read about notifications
  • Explore a falling or unchanged value: Separate estimation conditions—hills, indoor exercise, maximum heart rate settings, and device differences—from factors such as heat, sleep, illness, weight, age, and medication. Explore possible reasons

Choosing a method

  • If you have health concerns or a medical condition, consult a healthcare professional instead of relying on an estimate alone. See starting exercise safely for checks before you begin.
  • To track changes, use the same method under similar conditions. Estimation errors remain even then, so small changes alone do not establish a change in fitness.
  • Every estimate is a guide, not a diagnosis.

Your next step

Start by finding your smartwatch’s value

If you use a smartwatch, follow the manufacturer’s instructions to find the value. You can start exercising without a smartwatch.

Find instructions for your device

Sources

  1. Japan's Ministry of Health, Labour and Welfare: Physical Activity and Exercise Guide for Health Promotion 2023, INFORMATION 6, Cardiorespiratory fitness (peak oxygen uptake). (in Japanese; title translated) https://www.mhlw.go.jp/content/001195874.pdf
  2. Uth N, Sørensen H, Overgaard K, Pedersen PK. Estimation of VO2max from the ratio between HRmax and HRrest – the Heart Rate Ratio Method. Eur J Appl Physiol. 2004;91(1):111-115. https://doi.org/10.1007/s00421-003-0988-y
  3. Molina-Garcia P, et al. Validity of Estimating the Maximal Oxygen Consumption by Consumer Wearables: A Systematic Review with Meta-analysis and Expert Statement of the INTERLIVE Network. Sports Med. 2022;52:1577-1597. https://doi.org/10.1007/s40279-021-01639-y
  4. Google Health Help: About VO₂Max. (in Japanese; title translated) https://support.google.com/googlehealth/answer/14237924?hl=ja
  5. Apple. "Using Apple Watch to Estimate Cardio Fitness with VO2 max" (May 2021). https://www.apple.com/healthcare/docs/site/Using_Apple_Watch_to_Estimate_Cardio_Fitness_with_VO2_max.pdf
  6. Apple Support: Track your cardio fitness levels (published 16 September 2026). (in Japanese; title translated) https://support.apple.com/ja-jp/108790

No specialist review; sources providedContent last checked: Editorial policy