RHR, HRmax, SpO2, HRV, VO2 max—can the cardiovascular alphabet soup get any thicker?! There are seemingly endless metrics to track and (helpful though they may be), all those acronyms and numbers can get confusing and overwhelming, too. 

One popular fitness metric is VO2 max, which, in simplest terms, is a measure of cardiovascular fitness (how efficiently your heart, lungs, and blood vessels work during exercise). To break down what that all means, I connected with clinical exercise physiologist and certified strength and conditioning specialist Alexander Rothstein. Here’s what you’ve got to know.

Key Takeaways

• VO2 max is an indicator of cardiorespiratory fitness. 
• It is a measure of oxygen consumption; specifically, the maximum amount of oxygen your body can intake and utilize during exercise.
• VO2 max can be used as a predictor of race/event performance for multiple types of athletes.
• It’s best measured in a lab, but there are ways you can estimate it at home, such as with the Cooper exercise test.
• It’s normal for VO2 max to decline with age, and it gets harder (but not impossible) to improve it as you get older. 
• Sex assigned at birth and corresponding hormone levels, as well as body size and composition, also play a role in VO2 max.
• Improving VO2 max value requires training at very high intensities, often reaching and surpassing your lactate threshold and getting close to your maximum heart rate.
• High VO2 max is not associated just with physical fitness, but also health: It is associated with a reduced risk of cardiovascular disease.

What Is VO2 Max?

VO2 max refers to maximal oxygen consumption, measured in volume. 

“VO2 max represents our body’s physiological capacity to intake oxygen, deliver it to working cells, and use it at the cellular level to produce adenosine triphosphate (ATP), the energy currency of the body,” Rothstein tells BarBend. 

“It is not a direct measure of respiratory function or cardiac function, but instead represents the interaction between many body systems in order to produce energy as rapidly and efficiently as possible when the body is in need (when performing large amounts of movement such as high-intensity exercise),” he explains.

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The volume of oxygen you can consume is represented in milliliters of oxygen consumed per kilogram of body weight per minute (mL/kg/min). 

In other words, it’s a good indicator of maximal aerobic capacity, and finding it gives you a picture of your baseline aerobic fitness. “We can use VO2max values as a representative of cardiovascular health and it can help identify potential cardiorespiratory concerns and limitations individuals may have,” Rothstein says. “For individuals who are either high-performance athletes, or train recreationally and want to maximize their workout program, a VO2 max test can help do that.”

With that said, Rothstein says that VO2 max is a nice-to-have metric and not required. Most individuals can use submaximal testing and some non-exercise equations to estimate their VO2max, he says, which would suffice for most recreational athletes and fitness enthusiasts.

VO2 Max Chart

Typical, healthy VO2 max scores vary with age, sex, body size, body composition, and training history. The following are average values by age and sex assigned at birth (we need more research on nonbinary and trans people) provided by the American College of Sports Medicine (ACSM). All values are reflective of mL/kg/min. (1)

VO2 Max Averages for Women

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Data was not collected as to whether trans women were included in these statistics. More data is also needed for nonbinary people.

VO2 Max Averages for Men

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Data was not collected as to whether trans men were included in these statistics. More data is also needed for nonbinary people.

“Many of the components that make up VO2max are impacted by body size, and because of this it is common that men will have higher values than women,” Rothstein says. However, that isn’t necessarily representative of higher performance, because a larger body will also require more ATP. 

“This is partially accounted for in that relative VO2max values include a measure of body mass,” Rothstein explains, “although they don’t adjust for lung and heart size or blood volume, which all tend to be smaller in women, lowering their VO2 values.”

VO2 Max by Age

It’s normal for VO2 max to decrease as we age, Rothstein says, and the normative data reflects that. “It is also harder to improve as we get older, but it is not impossible,” Rothstein points out, adding that “it is never too late to improve cardiorespiratory health and function.”

• According to some research, VO2 max drops off significantly around middle age when comparing 41–50 and 50+ age group data to after age 41 to 21–30 and 31–40 age groups. (2)
• VO2 max is generally said to decrease by 10 percent each decade, but newer research suggests that figure may be oversimplified. Nonetheless, it remains true that it’s more difficult to improve VO2 max later in life. (3)(4)

How To Measure VO2 Max

The gold standard is lab testing. 

VO2 max is measured using a metabolic cart that simultaneously measures heart rate (cardiac output) and inspired and expired air (how much oxygen you breathe in and how much carbon dioxide you breathe out). These tests are also called cardio-pulmonary exercise tests (CPET) and are the most accurate way to measure VO2 max, according to Rothstein.

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Alternatively, because lab testing isn’t readily available to everyone, you can do a field test. This method involves using a submaximal protocol, which can use workload and heart rate to estimate VO2 max. You’ll wear a heart rate monitor and use a stopwatch to do this. Some tests, like the INSCYD running protocol, also use GPS data for greater accuracy.

There are dozens of ways to do this, from outdoor run tests to treadmill tests to walking tests. You can even find sport-specific protocols. A cyclist, for example, would get more value from a bike VO2 max test than a run test on a track. One example for runners is the Bruce Protocol test. 

How To Improve VO2 Max

Improving VO2 max requires high-intensity efforts in training. It often looks like what you may know as high-intensity interval training (HIIT). 

“The most important consideration when trying to improve VO2max is that for any sex, age, or athlete, the training intensity needs to be high enough to stimulate the body to adapt,” Rothstein says. “If the training stimulus is not large enough to signal the need to use resources to improve oxygen-consuming capacity, then the body will not adapt and maximal oxygen uptake will not improve.”

Another important note, Rothstein says, is that beginners will experience an increase in VO2 max very quickly: sometimes as quickly as within a week, as their cardiovascular system rapidly becomes more efficient and their blood plasma increases. 

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For more elite athletes, however, adaptations can take years, and it requires consistent training of sufficient intensity to signal the body that there needs to be an improvement in oxygen delivery and utilization.

VO2 max workouts involve short bursts of high-effort exercise. An example for running looks like: 

• 1-mile easy dynamic warm-up 
• 8x400m at 90% of HRmax 
• 3-minute rest or walk interval between sets 
• 10-minute easy cool-down 

Other types of training work as well, Rothstein says, “but the key is that the individual is training at a high enough intensity to signal the need for improvement.”

Fully aerobic exercise, like low-intensity, long jogs will not necessarily help improve VO2 max because you are not signaling the body that you need more ATP quickly—just that you need the same amount of ATP for a long period of time. 

“When jogging, you are performing long, steady-state exercise, so once the body has sufficiently reached the level to do that, it will not necessarily improve further [without high-intensity efforts],” Rothstein says.

Frequently Asked Questions

References

1. ACSM’s Health-Related Physical Fitness Assessment Manual, 5th edition. 2019. 
2. Xiang L, Deng K, Mei Q, et al. Population and Age-Based Cardiorespiratory Fitness Level Investigation and Automatic Prediction. Front Cardiovasc Med. 2022;8:758589. 
3. Kim CH, Wheatley CM, Behnia M, Johnson BD. The Effect of Aging on Relationships between Lean Body Mass and VO2max in Rowers. PLoS One. 2016;11(8):e0160275
4. Letnes JM, Nes BM, Wisløff U. Age-related decline in peak oxygen uptake: Cross-sectional vs. longitudinal findings. A review. Int J Cardiol Cardiovasc Risk Prev. 2023;16:200171.

Featured Image: Jacob Lund / Shutterstock