Demystifying watch data: What is VO2 Max?

By Brad Spokes

Running smartwatches today are more sophisticated than ever before. They now come loaded with features that provide insight into numerous physiological measurements. The amount of information they provide for athletes can be overwhelming.

This article will demystify a classic endurance sport metric …. VO2 Max.

Brad Spokes
Brad Spokes is a physiotherapist and one of the founding partners of ZONE Sports Physiotherapy

What is VO2 Max?

VO2 Max is the defining measure of cardiorespiratory fitness and aerobic performance capacity. VO2 Max, or maximal oxygen consumption, measures the maximum amount of oxygen a person can utilize during intense exercise. It is often considered a key indicator of cardiovascular fitness and endurance capacity.

VO2 Max measures the maximum volume of oxygen an individual can utilize during intensive exercise, and it is measured in millilitres of oxygen (ml) that the body can use per kilogram of body weight (kg) every minute (min).

VO2 Max is commonly described as “the size of the engine,” referring to how much oxygen your body can effectively use to produce energy during exercise. The rate at which your muscles use oxygen is proportional to the energy or power produced aerobically. Hence, VO2 Max is a valid indicator and aerobic energy system performance biomarker.

How is VO2 Max measured?

The gold standard of VO2 Max measurement is typically conducted in a specialized exercise physiology laboratory or medical clinic. Using a metabolic cart or metabolic analyzer allows for the analysis of the respiratory variables. This process allows for a precise measurement of VO2 Max.

In smartwatch technology, analytic engines embedded in your watch estimate your VO2 Max by identifying, analyzing, and interpreting performance data from your running. Your running pace is placed into the context of how hard your body is working to produce your performance. The relationship between internal input and external output (intensity of effort versus the pace you are running) is primarily linear and stable. Your body needs to work harder to run faster.

Measured in terms of VO2 Max, your fitness level, and insight from your activity history provide valuable context for personalizing training effect feedback, estimating recovery time, defining the optimal range for your weekly training load and determining your current training status.

How accurate are smartwatches in measuring VO2 Max?

The accuracy of VO2 Max measurements on smart watches or any other fitness device can vary. VO2 Max estimation on fitness watches is a complex calculation that involves factors like heart rate, age, gender, weight, and fitness level. While Garmin and other companies aim to provide accurate estimations, it is essential to understand that these are estimates and not direct measurements from a lab.

Factors that can affect the accuracy of VO2 Max measurements include the quality of heart rate data, individual variations, and the algorithm used by the device. It is worth noting that the accuracy of these measurements may depend on individual differences and the specific conditions under which the device is used. Factors like wrist placement, skin tone, and exercise intensity can impact heart rate accuracy, affecting VO2 Max estimates. It is recommended to ensure that your smartwatch is positioned correctly on your wrist during exercise to enhance the accuracy of VO2 Max estimates. Additionally, regularly updating your personal information on the device, such as age, weight, and fitness level, can help improve the accuracy of the calculations.

What’s a good VO2 Max?

The normal ranges for VO2 Max can vary based on factors such as age, sex, and fitness level. A value greater than 50mL/kg/min is considered good for males. For females greater than 40mL/kg/min.

For context, the highest recorded VO2 Max in males was 97mL/kg/min and 78mL/kg/min in females.

What are the benefits of improving your VO2 Max?

An increase in VO2 Max will increase your ability to burn lactate. A higher VO2 Max corresponds with better aerobic metabolism, allowing for a greater capacity to use oxygen and fat as fuel during workouts. A higher VO2 Max also results in a higher concentration of mitochondria in the muscle (the powerhouses of muscles where nutrients are broken down and turned into energy) and an improved blood flow to your working muscles.

Although genetics may limit an individual’s VO2 Max’s upper ceiling, the common misconception is that it cannot be trained. That is not true; VO2 Max is highly trainable through exercise.

Why, as a runner, you should pay attention to your VO2 Max:

  • Cardiovascular Fitness Assessment: VO2 Max is a reliable measure of cardiovascular fitness. By monitoring changes in VO2 Max over time, runners can assess the effectiveness of their training programs and identify improvements or areas that need more focus.
  • Performance Prediction: Higher VO2 Max values can be associated with better endurance performance in specific endurance events. While it is not the sole determinant of running performance, a higher VO2 Max generally indicates a greater capacity for sustained aerobic effort. Runners can use this information to set realistic performance goals and track progress.
  • Training Intensity: Understanding your VO2 Max can help structure your training intensity. Workouts that target specific percentages of your VO2 Max can be designed to improve your aerobic capacity. Workouts can include interval training, tempo runs, and other workouts tailored to enhance your cardiovascular system. VO2 Max training can be complex and tailored to the adaptation you are looking to achieve. The duration, intensity and density of intervals should be individualized based on athletes’ strengths and weaknesses and the event they are preparing for. Working with a sports medicine specialist or coach in this area can be beneficial to ensure you are getting the appropriate Vo2 Max intervals for your needs.
  • Individualized Training Plans: VO2 Max is unique to each individual, and knowing your value allows you to tailor your training plan to your specific needs. Personalized training programs based on your fitness level can be more effective in achieving your running goals.
  • Health Monitoring: VO2 Max is a fitness indicator and can provide insights into overall health. Regular monitoring can help identify changes that may warrant further investigation, such as declines indicative of health issues.
  • Efficiency Improvement: Training to improve your VO2 Max involves increasing your body’s ability to transport and utilize oxygen during exercise, leading to more efficient energy utilization, allowing you to sustain higher speeds for longer durations and recover quickly between efforts.
  • Motivation: Tracking improvements in VO2 Max can serve as a motivational tool. Experiencing positive changes in your fitness level over time can inspire continued dedication to your training regimen.

It is important to remember that while VO2 Max is a valuable metric, it is just one aspect of running performance. Factors such as running economy, lactate threshold, and mental resilience often play more crucial roles in determining your success in racing. Therefore, runners should consider VO2 Max as part of a comprehensive training and performance monitoring approach. Additionally, it is advisable to consult with a coach or health-care provider for a more comprehensive assessment of overall health and fitness.

Brad Spokes is a physiotherapist and one of the founding partners of ZONE Sports Physiotherapy.