Fitness is more than a feeling. With the right tools, it can be easily measured, and with the right perspective, easily managed. When health professionals talk about fitness, they usually mean cardiorespiratory fitness, which is measured as VO2 max.
VO2 max is a metric that describes your cardiorespiratory fitness. It measures the maximum amount of oxygen your body can use in one minute during intense exercise. This information is important for understanding your ability to sustain physical activity using aerobic energy. In other words, the higher your VO2 max, the more oxygen you can take in, transport and use to aerobically convert the energy in nutrients into performance.
Thinking about your fitness in terms of VO2 max — a vital health metric estimated by your Garmin device — has several benefits. For example, you know when you are fit enough to enjoy good health and when a lack of regular physical activity may be harming your wellbeing.
If you want to improve your fitness, tracking your progress as your VO2 max increases can be a powerful motivator. It is proof that you are on the right track, that your hard work is paying off and that your fitness is measurably improving.
VO2 max and health
The value of VO2 max as a general health indicator is indisputable. In 2016, the American Heart Association (AHA) issued an official statement recommending the regular assessment of cardiorespiratory fitness, measured by VO2 max, and its use as a clinical vital sign. They cited a well-known and growing body of research documenting the relationship between cardiorespiratory fitness, health indicators and mortality1.
Regarding mortality, the AHA notes that cardiorespiratory fitness is an even stronger predictor than traditional risk factors such as high blood pressure, smoking, type 2 diabetes, high cholesterol and obesity.
Understand and improve your VO2 max
Research on how the body uses oxygen and its importance for fitness and performance has been carried out for almost 100 years. However, the role of VO2 max as a fitness indicator has largely been limited to physiology research and findings by sports scientists working with elite athletes. This is because measuring VO2 max directly requires exhausting treadmill testing, during which the air exhaled by the athlete is collected and analysed in a laboratory2.
In recent years, thanks to the combination of wearable technology and physiological analysis, indirect VO2 max estimates based on performance data have become a fairly reliable alternative. Fitness can now be measured with high quality during everyday walks and runs3. The easy availability of this data has also raised awareness of what cardiorespiratory fitness really means and how it affects health.
When it comes to VO2 max, a higher value is usually better. What counts as a good level for you depends on factors such as age and sex. This is due to typical differences in body composition (the ratio of fat to muscle, bone and organs) and the decline in oxygen uptake capacity with age.
The good news is that basically anyone can improve their VO2 max through regular physical activity of the right intensity and duration. But perhaps you have already been training intensely for years and are already in great shape.
How Garmin measures your VO2 max.
Some Garmin devices automatically measure your VO2 max every time you record a run or brisk walk with heart rate monitoring and GPS tracking enabled. During activity, the built-in Firstbeat Analytics examines the relationship between your speed and the physical effort required to maintain that pace.
Some Garmin devices without built-in GPS can measure your VO2 max using accelerometer data, location data from a paired smartphone or bike computer, and GPS and power data.
Smart analysis ensures that only the most relevant part of your performance data is used. This means you don't have to worry about speeding up, slowing down or taking a break. Just carry on as usual and your watch does all the work, recognising when your performance accurately reflects your fitness.
Although strict rules aren't necessary, you should run or walk for at least 10 minutes. This ensures your muscles warm up and your heart, lungs and circulation can reflect the energy demand of the effort. For best results, at least part of the activity should be done at a minimum of 70% of maximum effort.
Because the analysis is designed to learn your performance parameters and patterns over time, recording more walks and runs improves the reliability of your VO2 max reading.
1American Heart Association, "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, vol. 134, pp. 653-699, 2016.
2N. M. Beltz, A. L. Gibson, J. Janot, L. Kravitz and C. M. Mermier, "Graded Exercise Testing Protocols for the Determination of VO2max: Historical Perspectives, Progress, and Future Considerations," Journal of Sports Medicine, vol. EPub, 2016.
3Firstbeat Analytics, "Automated Fitness Level (VO2max) Estimation with Heart Rate and Speed Data," White Paper, Jyväskylä, Finland, 2014.
