Setting a new personal max is a great way to chart your progress toward your fitness goals—so what’s the easiest way to do that? One useful step is to improve VO2 max, which is a measure of how much oxygen your body can take in and use during exercise. The more oxygen your body can put to use while you work out, the better your performance will be, whether you’re running a long-distance race or playing a sport like tennis or soccer.
How to measure your VO2 max
Your VO2 max is typically measured in a laboratory or medical setting, where they have you wear a mask that measures the amount of air you breathe in and out, as well as a heart rate monitor, while you work out, progressively increasing your exercise intensity. At some point, depending on your fitness levels, the amount of oxygen you are using will hit a plateau, at which point your body will switch from aerobic to anaerobic respiration. This is your VO2 max. Generally speaking, the higher the plateau, the better your fitness level.
Properly measuring your VO2 max requires a lot of specialized equipment, which means that it’s typically only done for specific purposes. There are other ways of estimating VO2 max which require less equipment, but aren’t quite as accurate, called submaximal exercise tests. These tests generally involve doing a structured exercise, such as running on a treadmill, with the results being used to calculate an estimated VO2 max. For example, the Cooper test has you run or walk as far as you can in 12 minutes, and then uses that distance to estimate your VO2 max. If your performance on the test improves, that’s a sign that your VO2 max has improved too.
The VO2 estimates provided by your activity tracker are calculated in different ways depending on the brand and model, but they usually involve comparing at running or walking speed with changes in your heart rate—but these measures are only rough estimates.
How to improve your VO2 max
There are two general strategies that are helpful for improving your VO2 Max. The first is to build up your aerobic base, which is achieved by doing a lot of lower-intensity aerobic work. In running, that would mean a lot of long, slow miles, with the goal of building up your mileage over time. Doing this increases your overall aerobic capacity, which in turn will help your body be more efficient at taking in and using oxygen.
As exercise physiologist and Ironman coach Alan Couzens noted in a blog post for SimpliFaster, in his experience working with athletes, the largest gains in VO2 max tend to come when their training plan includes a lot of lower-intensity aerobic work.
In addition to these long, slow miles, you’ll want to add to some more traditional “VO2 max” workouts, which feature short bursts of high-intensity work at 90-95% of your maximum heart rate. These short, intense bursts will help further push your body’s capabilities.
However, although it can be tempting (and feel good) to push yourself every time you exercise, high-intensity intervals should only comprise a small percentage of your overall workout routine—for example, if you are preparing for a race, you want to avoid overdoing them too soon. As Jason Fitzgerald wrote for Outside Magazine, you should avoid extended work at a VO2 max level, as it is tough on the body. Instead, he advises, “save most of these intense, specific workouts for the final phase of training when you’re sharpening for a race.”