What does a VO2 max test involve? How to prepare and what your results mean
A plain guide to VO2 max testing: what the number means, why it matters for your health, how the test runs at our Liverpool clinics, how to prepare and how to use your results.
VO2 max is one of the most talked about numbers in fitness. Running watches estimate it, but only a proper test measures it directly from the air you breathe.
If you are thinking about booking a VO2 max test, this guide explains what the test actually involves, how to prepare so your result is accurate, and what to do with the numbers afterwards.
What is VO2 max and why does it matter?
VO2 max is the most oxygen your body can take in and use during hard exercise. It is usually written in millilitres of oxygen per kilogram of body weight per minute (ml/kg/min).
It matters for more than race times. In 2016 the American Heart Association published a scientific statement arguing that cardiorespiratory fitness should be treated as a clinical vital sign, because low fitness is linked with a higher risk of heart disease and death, and adding it to traditional risk factors improves risk prediction (Ross et al., 2016).
Since then the evidence has grown. A Cleveland Clinic study of 122,007 adults who did a treadmill test, followed for a median of 8.4 years, found that the fitter people were, the lower their risk of dying during follow-up. The risk linked with low fitness was comparable to, or greater than, that of smoking or diabetes (Mandsager et al., 2018). An overview of meta-analyses covering more than 20.9 million observations found that people with high fitness had a 47% lower hazard of all-cause death than those with low fitness, and each one MET increase in fitness was linked with an 11 to 17% lower risk (Lang et al., 2024).
These are observational studies, so they show a strong link rather than proof of cause, and the certainty of evidence ranges from very low to moderate (Lang et al., 2024). Even so, the message is consistent.
Who is a VO2 max test for?
Most people who book with us are:
- Runners training for a 10k, half or full marathon who want training zones based on their own physiology rather than a formula.
- Cyclists and triathletes who want to know where their thresholds sit and track them across a season.
- Anyone tracking their fitness who wants a reliable starting point.
If you are preparing for a big race, the test fits naturally into our marathon preparation package or a wider athlete testing and movement analysis session.
How the test works at The Treatment Table
The test is a graded exercise test. You exercise on a treadmill or a bike, and the effort increases in steps until you reach your maximum. Throughout, you wear a VO2 Master portable analyser, a lightweight mask that measures the air you breathe in and out. A clinician watches your live metrics the whole time.
The hard part is short. Exercise physiologists usually aim for the increasing part of the test to last around 10 minutes, because early research found people reached their highest VO2 values when the test lasted roughly 8 to 17 minutes (Buchfuhrer et al., 1983). The same study found VO2 max was higher on a treadmill than on a bike, so it makes sense to test on the one that matches your sport, and to retest on the same one each time (Buchfuhrer et al., 1983).
Afterwards you receive a full written report. It includes:
- Your maximal metrics, including your VO2 max.
- Your ventilatory thresholds, the points where your breathing changes as the effort gets harder.
- Personalised training zones built from those thresholds.
- A comparison against population data for your age and sex.
How to prepare for a VO2 max test
Good preparation makes your result more accurate and repeatable. NHS leaflets for a similar maximal test give sensible guidance (Worcestershire Acute Hospitals NHS Trust, 2024; Cardiff and Vale University Health Board, n.d.):
- Rest beforehand. Avoid exercise for at least 24 hours before the test, so no hard sessions or long runs the day before.
- Eat lightly. Have a light meal at least two hours before.
- Skip the caffeine and alcohol before the test.
- Stay hydrated the day before and on the day.
- Wear your normal kit, comfortable clothing and the trainers or cycling shoes you train in.
- Keep taking your usual medication and bring a list of it with you.
If you plan to retest later, try to repeat the same routine each time so the comparison is fair.
Is a VO2 max test safe?
For most healthy people, yes. The American Heart Association describes exercise testing as generally safe, while noting that serious events are rare but possible, and that the risk depends largely on whether someone has underlying heart disease (Fletcher et al., 2013). Warning signs often come before a serious cardiac event (Riebe et al., 2015), which is why we ask screening questions before every test.
A maximal test is not suitable for everyone. Exercise testing should not be done in people with, for example, a recent heart attack, unstable angina, uncontrolled heart rhythm problems, symptomatic severe aortic valve narrowing, decompensated heart failure, a recent blood clot in the leg or lung, or acute inflammation of the heart (Fletcher et al., 2013). We also won't test you if you are acutely unwell, for example with a chest infection or fever. If screening raises a concern, we will point you towards a medical check first.
Feeling very breathless, hot and tired at the end of a maximal test is normal. If you feel unwell during the test, we stop.
When to get checked urgently
If you get chest pain, pressure or tightness, faint or nearly faint, or have breathlessness or palpitations during exercise that feel out of proportion to the effort, stop exercising and get medical advice. If symptoms are severe or don't settle, call 999. Get checked by a doctor before booking any maximal fitness test.
What your results mean
Your VO2 max is most useful compared with others of your age and sex, and with your own future results. The table below shows reference values from the US FRIEND registry, based on 7,783 maximal treadmill tests with measured gas analysis in adults without heart disease (Kaminsky, Arena and Myers, 2015). The middle range covers the 25th to 75th percentiles, so half of people fall inside it.
| Age | Men, median | Men, middle range | Women, median | Women, middle range |
|---|---|---|---|---|
| 20 to 29 | 48.0 | 40.1 to 55.2 | 37.6 | 30.5 to 44.7 |
| 30 to 39 | 42.4 | 35.9 to 49.2 | 30.2 | 25.3 to 36.1 |
| 40 to 49 | 37.8 | 31.9 to 45.0 | 26.7 | 22.1 to 32.4 |
| 50 to 59 | 32.6 | 27.1 to 39.7 | 23.4 | 19.9 to 27.6 |
| 60 to 69 | 28.2 | 23.7 to 34.5 | 20.0 | 17.2 to 23.8 |
| 70 to 79 | 24.4 | 20.4 to 30.4 | 18.3 | 15.6 to 20.8 |
All values are in ml/kg/min and come from treadmill tests. Bike results tend to be a little lower (Buchfuhrer et al., 1983), so compare like with like.
Using your training zones
For most people the training zones are the most useful part of the report. Because they are built from your own ventilatory thresholds, they tell you how easy your easy runs or rides should really be, and where your harder sessions should sit. Pairing zone based training with regular strength work for runners is a sensible way to build fitness while looking after your joints and tendons.
When to retest
Retesting after a block of training shows whether your fitness and thresholds have moved, and lets us update your zones.
Related tests
A VO2 max test costs £150. If you want more detail, a lactate threshold test (£250) uses small blood samples to track lactate as the effort rises, and a resting metabolic rate test (£100) measures how much energy you burn at rest. Our 360 metabolic profile (from £500) brings these together.
VO2 max testing at The Treatment Table
We run VO2 max tests at our clinics in Seaforth (Fitness Connection, 83 Seaforth Road, L21 3TY) and Speke (Business First Centre, Goodlass Road, L24 9HJ). You don't need a GP referral.
We are open Monday to Friday 7am to 8pm and Saturday 10am to 4pm. Book your VO2 max test, call 0151 559 1107 or email info@thetreatmenttable.com.
References
Buchfuhrer, M.J. et al. (1983) 'Optimizing the exercise protocol for cardiopulmonary assessment', Journal of Applied Physiology, 55(5), pp. 1558 to 1564. doi:10.1152/jappl.1983.55.5.1558.
Cardiff and Vale University Health Board (n.d.) Cardio pulmonary exercise testing (CPET). Available at: https://cavuhb.nhs.wales/files/lung-function-and-sleep-apnoea-department/cpetpdf/ (Accessed: 2 November 2026).
Fletcher, G.F. et al. (2013) 'Exercise standards for testing and training: a scientific statement from the American Heart Association', Circulation, 128(8), pp. 873 to 934. doi:10.1161/CIR.0b013e31829b5b44.
Kaminsky, L.A., Arena, R. and Myers, J. (2015) 'Reference standards for cardiorespiratory fitness measured with cardiopulmonary exercise testing: data from the Fitness Registry and the Importance of Exercise National Database', Mayo Clinic Proceedings, 90(11), pp. 1515 to 1523. doi:10.1016/j.mayocp.2015.07.026.
Lang, J.J. et al. (2024) 'Cardiorespiratory fitness is a strong and consistent predictor of morbidity and mortality among adults: an overview of meta-analyses representing over 20.9 million observations from 199 unique cohort studies', British Journal of Sports Medicine, 58(10), p. 556. doi:10.1136/bjsports-2023-107849.
Mandsager, K. et al. (2018) 'Association of cardiorespiratory fitness with long-term mortality among adults undergoing exercise treadmill testing', JAMA Network Open, 1, e183605. doi:10.1001/jamanetworkopen.2018.3605.
Riebe, D. et al. (2015) 'Updating ACSM's recommendations for exercise preparticipation health screening', Medicine and Science in Sports and Exercise, 47(11), pp. 2473 to 2479. doi:10.1249/MSS.0000000000000664.
Ross, R. et al. (2016) 'Importance of assessing cardiorespiratory fitness in clinical practice: a case for fitness as a clinical vital sign: a scientific statement from the American Heart Association', Circulation, 134, pp. e653 to e699. doi:10.1161/CIR.0000000000000461.
Worcestershire Acute Hospitals NHS Trust (2024) Patient information: cardiopulmonary exercise testing (CPET), WAHT-PI-0427. Available at: https://apps.worcsacute.nhs.uk/KeyDocumentPortal/Home/DownloadFile/4345 (Accessed: 2 November 2026).