An individual’s maximum capacity to extract, transport, and utilize oxygen is reflected by their VO₂ max. VO₂ max can be affected by the capacity of one’s organ systems (i.e. cardiac, pulmonary, etc.). Other factors that can affect a person’s VO₂ max are genetics, body type, age, gender, endurance, and athletic ability. VO₂ max is arguably the best way to assess one’s cardio-pulmonary endurance. This measure is typically used in high-level athletes to see how they can improve their oxygen utilization in sport. However, beginners to intermediate-level athletes may also inquire about VO₂ max testing in the clinical setting. This is because people with better endurance/physical activity levels usually have lower rates of disease, longer lifespan, and overall better health. Measuring gas exchange of oxygen and carbon dioxide using a metabolic cart, theoretically lets us measure one’s VO₂ max to assess their maximum aerobic endurance. Thus, potentially allowing us to assess one’s longevity and overall health in a clinical setting.
Assessment
There are multiple ways to assess one’s VO₂ max, including many different protocols, which I will briefly dive into in the next section. Ideally, we would assess VO₂ max using one of the many treadmill testing protocols. The first part of any VO₂ max test is setting up the equipment. Along with a treadmill, we need a computer that has capabilities to calculate gas exchange, a mask to both limit air that escapes and to attach to a tube. The tube will also be used to attach the mask to the computer. The participant will wear this fancy mask that attaches to the tube, which attaches to the computer all while they run. The downside to this is that the mask is usually tight and uncomfortable, which may reduce the patient’s performance slightly. However, this is the best tool to see how well the participant exchanges gas.
Like the treadmill test, there is also a bicycle test. It pretty much involves the same setup but instead uses a stationary bike. This form of testing also has its pros and cons. The pros include less movement while cycling, which is less likely to cause the mask or any other piece of equipment to fall off during testing. The cons include a possible, up to 10% reduction in measured VO₂ max. There are 2 reasons for this. The first reason is that most people are not used to cycling and are more used to running, therefore testing on a bicycle may not be as ergonomic for that participant. The second reason is that less muscle mass is engaged in cycling when compared to running. Running involves movement of the legs (obviously), but also swinging of the arms, which engages more muscle groups than cycling might. Again, these are all theoretical variables in measurement. On the contrary, cycling would be a better option for someone who mostly trains cycling as opposed to running.
Protocols
As mentioned earlier, there are several protocols used to test VO₂ max. Generally, testing will involve a warm-up phase and then a gradual increase in intensity of the workout. There are 2 ways to increase exercise intensity. One is to increase the incline, only if the patient is running on the treadmill. Another way is to increase resistance, only if the patient is cycling. The last way, which can be done in both scenarios, is to increase the speed at which the participant is running or cycling. Depending on the protocol, we can either adjust resistance, incline or speed OR; we can adjust all 3. The most common protocols that we use are the Astrand Protocol, Bruce Protocol, and Ellestad Protocol. However, there are several others that exist.
In our clinic, we typically use the stationary bike for testing as it is easier from a technical standpoint to complete. There is less chance of equipment failure and mispositioning. After the participant is fitted for the mask and hooked up to the computer, we have them begin their warmup phase for 2 minutes, then we will gradually increase the resistance at 2-minute intervals. Ideally, at the end of the test, the participants will be exerting themselves maximally until failure. The test typically takes anywhere between 10 and 15 minutes.
The Apple Watch and other smart watches do offer a VO₂ max “measurement,” however it usually just uses an algorithm based on your heart rate. Unfortunately, it is not an accurate measurement of VO₂ max. Hopefully in the future there will be better technology that we will be able to utilize for more accurate and easier VO₂ max testing.
How to Increase VO₂ Max
Before I get into the bread and butter of increasing VO₂ max, I need to talk about Rate of Perceived Exertion (RPE), Max Heart Rate (Max HR) and Lactate Kinetics. RPE, Max HR, and Lactate Kinetics often go hand in hand. RPE is simple. It is a scale of 1-10, and it involves the participant rating how intense their exercise is. 1 is a very low intensity exercise, while 10 is a maximally intense exercise. If someone wants to increase their VO₂ max; they need to exercise at an RPE of about 7 or higher.
Max HR is also a good way to measure exercise intensity. Thankfully, this measurement usually follows the same curve as RPE. Depending on age and fitness, max HR can vary. Typically, Max HR ranges from 150-200 beats per minute. To calculate your own max heart rate, take the number 220 and subtract your age. For example, a 45-year-old should have a max HR of 175 (220 – 45 = 175). To increase your VO₂ max, you should have your heart rate ranging from 65-85% of your max HR. For example, this would be about 115-150 beats per minute for a 45-year-old. Therefore, when you exercise, you can make sure you are hitting these heart rate targets, which can easily be done with an Apple Watch or another smart watch.
Finally: how to increase VO₂ max. While training at an RPE of 10 or at Max HR or Zone 5 in lactate kinetics would be ideal; it is impossible to maintain that level of exertion for a long period of time. So, how do we combat that? Well, the best way to do so is High Intensity Interval Training or HIIT. This involves training for about 2 minutes at an RPE of about 7 or higher, followed by a 3-minute period of an RPE of about 2-3. You can also adjust the intervals of time as well as the RPE. For example, if you are going to be training at an RPE of 10, I recommend only doing this for about 30 seconds followed by a 2-minute period of an RPE of 1-2. Again, the goal is to be working at an RPE of at least 7 and a HR at 65-85% of max. However, you want to exercise and break up those numbers depending entirely on what your goals are and what exercises you enjoy doing.
VO₂ Max and Longevity
Some of you may have read Peter Attia’s book, “Outlive” and if not, that’s ok too. I won’t go into as much detail as he does but will summarize key details. Higher VO₂ max is associated with longevity, decreased risk of disease, and increased lifespan. Typically, people who are not professional athletes do not measure their VO₂ max, but it may be a good idea to do so. Increasing your VO₂ max even slightly can reduce your mortality significantly. It reduces your risk of diabetes, heart disease, high blood pressure, and kidney disease. I’m not saying you need to start training like an Olympian, but even a small improvement in physical fitness may lead to a longer, happier life.