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Your VO2 max, explained

Runner, triathlete and exercise physiology Ph.D. candidate Alexandra Coates explains what your VO2 max is, why it's important and what you can do to improve it

man sprinting

The VO2 max is considered the gold standard for assessing the aerobic or endurance fitness of an individual, and you’ve likely heard the term come up in conversation with your running friends more than once. But what is it, exactly, and is it really as important as we think it is? We spoke with Alexandra Coates, a runner, professional triathlete and exercise physiology Ph.D. candidate, who told us everything you need to know about your VO2 max.

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What is the VO2 max?

Coates explains that your VO2 max is the maximum amount of oxygen your body can use during dynamic exercise. Also referred to as your maximal aerobic power, it is a measure of your body’s ability to transport and use oxygen while doing aerobic exercise, like running. How big and strong your heart is, how much blood and red blood cells you have and how good your blood flow is to the working muscles, as well as how much oxygen your mitochondria (the powerhouses of your cells) consume, are all reflected in your VO2 max.

How can you determine your VO2 max?

To properly measure your VO2 max, Coates says you would need to go to an exercise physiology lab that has a metabolic cart. A metabolic cart measures the volume of oxygen that your body uses, and the volume of carbon dioxide that you produce during exercise through the gas concentrations and rates of your inspired and expired breaths. In the lab, you would take a VO2 max test, which is always going to be some version of an incremental (or ramp) exercise test, where you are either running, cycling, or even rowing while wearing a mask that is connected to the metabolic cart.

The beginning of the test would start off fairly easy, and should get gradually harder and harder so that by the time you’ve been running for around eight to 12 minutes, you are going as hard as you possibly can. An exercise physiologist can tell when you’ve reached your VO2 max because your oxygen consumption will plateau or perhaps even decrease, even though your exercise intensity is increasing.

Of course, very few of us will ever find ourselves in an exercise physiology lab, but that doesn’t mean you can’t at least get a rough idea of where your VO2 max is. There are equations and calculators that you can use to determine your VO2 max, simply by inputting recent race or workout results. If you’d like to determine roughly what your VO2 max is, Coates suggests using the Daniels Running Formula.

Vo2 max test.

How important is VO2 max, really?

“VO2 max certainly plays a big part in running performance for any endurance event,” says Coates, “as it represents the maximal work-rate that you can perform. VO2max is directly proportional to how fast you will end up running at the end of the ramp test, and how fast you can run a 5K, 10K, half-marathon or marathon.”

She adds, though, that VO2 max isn’t everything, and an individual can have a very high VO2 max genetically, but be relatively untrained and have poor running economy. She also notes that a high VO2 max doesn’t protect you from injuries. The other important piece of the puzzle is how close to your VO2 max you can work without hitting your anaerobic threshold, which is the highest exercise intensity you can sustain for a prolonged period of time without lactate building up in your blood.

“Being able to work at a very high percentage of your VO2 max seems to be what separates the good athletes from the best,” explains Coates, “not VO2 max itself.”

She gave us the following example: say you have two athletes, athlete A and athlete B, both with the same running economy. Athlete A’s VO2 max is 60 ml/kg/min, and athlete B’s VO2 max is 65 ml/kg/min. In a 5km race, athlete A is able to work at 95 per cent of their VO2 max for the duration of the race, meaning that they are consuming 57 ml/kg/min of oxygen throughout the race. Athlete B, on the other hand, can only work at 85 per cent of their VO2max for a 5K, resulting in a VO2 of 55 ml/kg/min during the race, which ultimately means they will not be able to sustain the same running velocity as Athlete A, even though they have a higher VO2 max.

Can you improve your VO2 max?

The good news is, you can — at least partly. Coates tells us most of the research has determined that 50 per cent of your VO2 max is genetic, and the other 50 per cent is trainable. Some people can improve their VO2 max dramatically simply from doing long endurance sessions, while others will require high-intensity intervals, tempo-threshold runs and 1K to 2K repeats. Interestingly enough, recent research has shown that people with higher VO2 maxes tend to live longer, so training your aerobic threshold will not only make you a better runner, it will make you a healthier person overall.

The bottom line

Your VO2 max is an important predictor of your running abilities, but it isn’t the only important performance metric. VO2max, running economy, and percentage of sustainable VO2max are the main factors that dictate performance, and to see significant improvements you need to work on all three of these areas. Luckily, Coates says running economy is largely improved simply by running more, so with time, your running economy will likely improve on its own. Finally, while we all love to get faster, the most important reason we run is to stay healthy, and training your VO2 max can help you do exactly that.

“Aerobic fitness is good for you,” Coates says, “so work with the 50 per cent VO2max trainability that you have to try to be fit across your lifespan.”

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