VO2 max testing

What is a VO2 max test?

VO2 max is the maximum (max) rate (V) of oxygen (O2) your body can absorb and use during exercise. Finding out your VO2 max level can give us an insight into your aerobic health and overall cardiovascular fitness. VO2 max is measured as ml/kg/minute (millilitres of oxygen consumed per kilogram of body weight per minute of exercise).

When you breathe in, your lungs absorb oxygen and convert it into energy called adenosine triphosphate (ATP). ATP helps power your cells and release CO2, which is created as a by-product during the respiratory process. The more oxygen you can take in and absorb, the higher the amount of ATP produced and the greater your capacity for exercise.

When assessing your heart, a VO2 max test can show how well your heart pushes blood to your muscles and how efficiently your muscles can extract oxygen from your circulating blood.

Why do I need a VO2 max test?

This test measures your body’s maximum oxygen use during exercise, providing an accurate assessment of your aerobic fitness. It helps us see how well your heart, lungs, and muscles work together when you exercise.

It can help personalise exercise training, track your fitness progress, optimise athletic performance, and evaluate your general cardiovascular health. This test is valuable for athletes, fitness enthusiasts, and anyone looking to improve or monitor their overall health.

If you get tired easily or have trouble breathing, this test can show if your heart is the cause. Your cardiologist may recommend it to find out how strong your heart is, to help diagnose heart problems, and to decide the best treatment for you.

Procedure

Like an exercise ECG, we will ask you to do a short exercise activity on either a treadmill or an exercise bike, with the intensity increasing until you reach the maximum level. However, we will be looking at and monitoring your oxygen levels rather than your heart.

Before you start the test, we will fit you with a face mask connected to a recording device that will record your respiratory rate and volume as well as the levels of oxygen and carbon dioxide in the air you exhale and inhale. We will also attach a heart rate monitor. We will take readings at rest before starting the exercise to use as a basis to compare your results against.

With the face mask attached, we will ask you to participate in the exercise activity for 10 to 20 minutes. We will stop the test once your VO2 levels have reached their maximum. Your VO2 max is reached when your oxygen consumption steadies despite increased exercise.

Preparation

We recommend wearing light, easy-to-wear exercise clothing and shoes (preferably trainers) to feel as comfortable as possible while participating in the activity. 

You must not smoke, drink alcohol, or consume caffeine for at least 3 hours before the test. We also advise you not to exercise 24 hours before your appointment.

Certain medications can interfere with the test. We will discuss with you what you are currently taking and whether we need to adjust them in order to perform the test. 

Testing should be avoided if you have had a respiratory, gastrointestinal, or other illness within 2 weeks of the test, as this can affect your results.

Results and aftercare

After reaching your maximum VO2 level, we will ask you to stop exercising and recover from the activity. You may feel tired for a few hours after the test, especially if you don’t exercise regularly, but this is normal. However, if you feel fatigued for more than a day, contact us immediately for a follow-up.

Results will vary from person to person, depending on your age or the amount of exercise you do.

Average VO2 max levels for men, aged 18-45

Average VO2 max levels for women, aged 18-45

A sedentary (low) VO₂ max level can signal that you may be at a higher cardiovascular risk, including increased chances of high blood pressure, elevated cholesterol, obesity, and heart failure.

In contrast, an active (high) VO₂ max level indicates better cardiorespiratory fitness and is connected with a lower risk of cardiovascular disease. Research has shown that even modest improvements in VO₂ max resulting from increased physical activity can significantly reduce heart health risks and improve long-term health outcomes.

If your VO2 is lower than you’d like, we can help you improve your levels through a tailored exercise routine.

Partnered with Anthem Healthcare, we can guide your fitness journey with one of London’s leading personal trainers, who specialise in injury prevention and functional training. With guidance from our expert Cardiologist, Dr Ravi Assomull, we will put your heart health at the forefront of your treatment and exercise regimen.

Frequently asked questions

Is this test safe?

A VO2 test is generally considered safe, especially when performed under the supervision of trained professionals. However, as it does require physical exercise, it has some mild risks such as fatigue, dizziness, muscle strain, and, in rare cases, abnormal heart rhythms or other cardiovascular events, particularly for those with pre-existing health conditions. If you experience any medical concerns, we advise you to consult your doctor before taking part in this test and follow all safety protocols during testing.

How accurate is it compared to other heart tests?

A VO₂ max test is one of the most accurate and reliable ways to measure how well your heart, lungs, and muscles work together during exercise, providing a direct assessment of your fitness and exercise tolerance. While other cardiology tests like ECGs and echocardiograms are important for checking heart structure and rhythm, they don’t measure your body’s ability to use oxygen during activity as precisely as a VO₂ max test. This makes the test especially valuable for tracking your functional capacity and guiding your treatment plan.