One of the most important goals of any exercise regime should be to improve aerobic capacity. What is that? How can we measure it and how can we improve it?
The cells in our bodies have two ways of generating energy in the form of ATP (Adenosine triphosphate): The aerobic pathway and the anaerobic pathway.
The aerobic pathway which requires oxygen is the predominant pathway we use at rest. This is because it is extremely efficient in generating energy. The aerobic pathway generates 30 molecules of ATP per one glucose molecule compared to only two by the anaerobic pathway (which does not require oxygen). That’s 15 times more ATP.
This is why increasing our aerobic capacity is important. It allows us to get more bang for our buck (or more ATP for every glucose molecule) before we have to tap into the less efficient anaerobic pathway. One of the best predictors of this is ‘maximal aerobic capacity’ or VO2 max for short.
VO2 max is the maximum amount of oxygen your body can utilise during exercise
What is a good VO2 max?
Generally, the higher the better. It can vary between men and women and by age group. VO2 max typically declines with age therefore slowing the decline of VO2 max with age is probably a good indicator of slowing down the aging process of the heart and lungs. VO2 max has been shown to be an important predictor of cardiac health and disease.
Typical VO2max fitness scores for men by age group:
Typical VO2max fitness scores for women by age group:
How to measure VO2 max?
Actual VO2 max (most accurate)
Usually requires a fitness lab. Your heart and respiratory rate will be measured along with the concentration of exhaled and inhaled oxygen and carbon dioxide. This is done while exercising on a treadmill with varying intensities for 20 minutes usually.
Another way is to use commercially available wearables that can give you an estimate. Apple watch (not visible directly on the watch on Apple watch interface but can be found using the Health app on your iPhone in the Respiratory section) and Garmin are two examples.
How can you improve VO2 max?
Aerobic exercise in general can improve VO2 max, however, there have been many studies comparing different exercise routines and they are not all equal.
“Zone 2 training”
Zone 2 training refers to moderate intensity exercise that lasts for a sustained period of time (more than 30 minutes). It can be done by following heart rate zones (which are percentages of exercise heart rate to your maximum heart rate). This is done by exercising for a sustained period of time at a heart rate of 70-80% of your maximum heart rate (HR max). HR max can be estimated using this formula:
Estimated HR max = 220 - age
It can also be done by paying attention to your breathing rate. This is to estimate something called your first and second ventilatory thresholds (studies suggest that a ventilatory threshold method of training may be more effective than heart rate training for improving VO2 max). Hitting your first ventilatory threshold or VT1 is a good indicator that you’re in zone 2. This is the moment when your breathing rate changes and you no longer can recite the alphabet without taking a breath mid-way for example.
A good target to aim for would be to exercise in zone 2 for a total of more than 150 minutes a week in 3-4 daily sessions.
High intensity interval training or HIIT
High intensity training has been shown to be more effective than zone 2 training when it comes to improving VO2 max. However, in my experience it is a more advanced option that many people need to work up to. HIIT usually means exercising at more than 90% of our maximum heart rate or at our second ventilatory threshold (VT2) for short intervals (seconds to minutes) split by periods of moderate to low intensity exercise. You can tell you have reached VT2 when you can no longer speak except for single short words such as “yes” or “no”. A common regimes
A good target to aim for would be to do 4 cycles of 4 minutes in high intensity then 4 minutes of low to moderate intensity in between. Repeat this 2-3 times a week.
Effectiveness of High-Intensity Interval Training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials https://pubmed.ncbi.nlm.nih.gov/26243014/