Why You Should Care About VO2 Max
By Nike Running
Improving this metric can make you a speedier, healthier runner.
Help your running and overall health by learning how to connect and improve your VO2 Max through pushing your comfort zone in training.
Running has a lot of important numbers: pace, goal time, heart rate, the effort you feel like you're giving (on a scale from 1 to 10, naturally). Your VO2 max, a benchmark for aerobic fitness, is one of those key stats.
To understand how improving this number can make you a better runner—and a healthier human in general—we've pulled in experts to break it down.
What Is VO2 Max?
The "V" stands for volume, "O2" stands for oxygen, and "max" refers to maximum. What it all equals is a measurement of the highest volume of oxygen your body can use during exercise. That number is important because it can indicate how fit you are overall.
Calculating VO2 max is heady stuff. The measurement is typically expressed as millilitres of oxygen consumed per kilogramme of body weight per minute (ml/kg/min). To precisely capture that, it's traditionally tested in a sports-science laboratory while an athlete runs at maximum effort on a treadmill, says Aaron Coutts, PhD, a distinguished professor in sport and exercise science at the University of Technology Sydney.
While activity trackers can estimate your VO2 max, there's no real way to measure it at home. However, it's pretty easy to tell when your VO2 max is increasing, especially for newer runners. "It's based upon fitness", says Ian Klein, a specialist in exercise physiology, cross-training and injury prevention at Ohio University. "The longer you can run without getting tired, the higher your VO2 max probably is".
How VO2 Max Connects to Your Run Speed
A higher VO2 max means your body can deliver more oxygen to your muscles as you run, which can give you the ability to go faster even as your workouts get harder, explains Klein. Commonly, if you have a high VO2 max you also have a high lactate threshold. That means you can work at a higher intensity for a longer period of time before your body begins to build up lactic acid, fatigue sets in and you're forced to pull back.
Most runners are familiar with that "oh no, gotta pump the breaks" feeling. That's called crossing the anaerobic threshold, and here's what's going on inside your body to cue it: Your muscles start to accumulate hydrogen ions and lactate faster than your body can clear them, says Klein. "Hydrogen ions are converted into CO2, and the more you're working a muscle anaerobically, the more CO2 you're going to have", he explains. "While CO2 is present, it prevents oxygen from being transported efficiently. If you can't get rid of CO2, you have no place for oxygen to bind to". And with no more oxygen, there's no more sprinting at an all-out pace.
"Once the oxygen is there, it's easy to turn into energy."
Exercise physiologist Ian Klein
The better your VO2 max, the more efficiently your body can remove that CO2, and the more oxygen your red blood cells can hold and deliver to your muscles to keep pumping. Specifically training your body to boost your VO2 max (more on how to do that below) also helps develop more capillaries in the muscles, says Klein, which, again, means you can get more oxygen to the muscles. "Once the oxygen is there, it's easy to turn into energy", he says—helping you run stronger and faster.
Why a Better VO2 Max Means Better Health
A higher VO2 max has a cascade of positive benefits: Your lungs can more efficiently take in and send oxygen to your muscles, including your heart. This means your heart is able to pump more blood with each heartbeat, which lowers your resting heart rate. And that efficiency means your entire cardiovascular system is under less stress.
To register the long-term health effects of this, look at the other end of the spectrum: Low levels of cardiorespiratory fitness—or a lower VO2 max—are associated with a high risk of cardiovascular disease, dying from any cause, and various cancers, according to the American Heart Association. In fact, the AHA says cardiorespiratory fitness is a stronger predictor of mortality risk than factors such as smoking and high blood pressure.
And that could explain why research shows that improving your VO2 max may reduce your risk of serious health conditions (as if besting your 5K PR wasn't enough).
How to Up Your Number
The bad news: Your potential for your highest VO2 max is influenced by genetics (another reason why most of us will never run like Eliud Kipchoge). The good news: You're likely a long way from operating at your uppermost threshold, and you can improve your number.
"Nobody said increasing your max would be easy, but you will be better for it."
Professor of sport and exercise science Aaron Coutts
To do that, you want to be comfortable running long, slow distances and doing faster, more challenging workouts. Once you've established a good base of fitness, you can focus on high-intensity interval training, or HIIT. These sessions alternate hard or all-out efforts with recovery bouts, and doing them is one of the most effective ways to increase your VO2 max and lactate threshold, says Coutts. "Yep, time to push past your comfort zone", he says. "Nobody said increasing your max would be easy, but you will be better for it."
Better how, exactly? Well, holding higher intensities for short intervals pushes your anaerobic system to its lactate threshold, Klein explains, which over time makes it more efficient at performing at those intensities for longer periods. He says the intensity you're shooting for falls somewhere between an 800-metre sprint and an all-out 2-mile pace. This kind of gnarly effort, Klein says, "provides the metabolic and physiological stress your body needs to adapt, grow stronger and increase your VO2 max".
Science agrees. HIIT is proven to help boost your VO2 max, according to research in the journal Medicine & Science in Sports & Exercise. And a review of several studies shows that HIIT routines lead to greater gains in VO2 max compared to endurance training.
Let that be fuel to take it to the max in your next interval workout.
Check out guided Speed Runs on Nike Run Club.