If your smartwatch has ever flashed a “VO₂ max” score or you’ve heard runners comparing numbers and you have wondered what it really represents, you are in the right place.
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As one of the strongest predictors of cardiovascular health, endurance potential, and even life expectancy, knowing about this performance stat — and working to improve it — can have a huge impact on your fitness.
Let’s break down what is and what having a higher score could mean for your health.
What is VO₂ Max?
VO₂ max stands for maximal oxygen uptake, or the highest rate at which your body can take in and use oxygen during intense exercise.
In plain terms, VO₂ max reflects how efficiently your heart, lungs, blood, and muscles work together when you’re pushing hard. The higher your VO₂ max, the longer and harder you can go before fatigue sets in.
It’s usually reported as milliliters of oxygen per kilogram of body weight per minute (mL/kg/min). This “relative” number makes it easier to compare across different body sizes, while absolute values (liters per minute) are sometimes used in clinical or research settings.
How VO₂ Max Is Measured
The most accurate way to test VO₂ max is in a lab using cardiopulmonary exercise testing (CPET). You run or cycle while wearing a mask that measures oxygen intake and carbon dioxide output, with the workload gradually increasing until you can’t continue. Because this test pushes people to their limit, it should be medically supervised for anyone with heart risks.
The highest value you reach in a test is sometimes reported as VO₂ peak. That usually means the test stopped at your top effort without confirming the “plateau” that defines a true VO₂ max — when oxygen use starts to level off even though the workload is getting harder. This often happens in clinical settings, where safety comes first, or simply because of how you feel that day. For most healthy exercisers, the distinction isn’t important. Both reflect aerobic capacity. What really matters is how your number changes over time.
Outside the lab, most people rely on estimates. Fitness watches use pace and heart rate data to provide ballpark VO₂ max scores, and field tests like the Cooper 12-minute run can offer useful, though less precise, results.
VO₂ Max and Long-Term Health
VO₂ max is closely tied to endurance performance, but it’s arguably just as crucial for health.
Studies show it may predict longevity more strongly than cholesterol levels or blood pressure. One analysis found that every 3.5 mL/kg/min increase in VO₂ max was associated with about an 11% reduction in risk of death from any cause.
Another large review concluded that people with high aerobic fitness had roughly half the mortality risk compared to those with low fitness.
That’s why the American Heart Association has argued that aerobic fitness should be considered a “vital sign” in routine healthcare, right alongside blood pressure and resting heart rate.
What’s a “Good” VO₂ Max?
There isn’t one perfect number for everyone. VO₂ max changes with age, sex, and activity level.
According to treadmill testing data from The Fitness Registry and the Importance of Exercise National Database (FRIEND), average VO₂ max values are:
- Men
30–39 years: 42.8 mL/kg/min - Women
30–39 years: 33.0 mL/kg/min
VO₂ max naturally declines with age, dropping by about 5–10% per decade after your 20s, research shows.
Elite endurance athletes go far beyond population norms, with some men measured above 80 mL/kg/min.
For general health, maintaining at least 35–40 mL/kg/min for men and 27–31 mL/kg/min for women is associated with lower cardiovascular risk.
What Shapes VO₂ Max?
Several factors influence where your VO₂ max starts and how much it can change:
- Genes: Roughly half of your VO₂ max capacity comes down to the way your heart, lungs, and muscles are built based on your DNA.
- Age: VO₂ max typically peaks in your 20s and gradually declines with age, though regular exercise slows the drop.
- Training: Active people maintain higher VO₂ max scores longer than sedentary people. Endurance athletes often score two or three times higher than the average person.
Can You Improve VO₂ Max?
The good news is that VO₂ max isn’t fixed. Most people can raise their numbers by 5–15 percent with consistent training over 8–12 weeks.
High-intensity interval training (HIIT) is one of the most effective methods. Intervals lasting three to five minutes at close to maximum effort challenge the cardiovascular system to adapt, often more efficiently than steady cardio alone. That said, long endurance workouts build a strong aerobic foundation, and strength training helps muscles use oxygen more effectively.
Even older adults can see meaningful improvements. Research shows people in their 60s and 70s can raise VO₂ max by around 10 percent after just a couple of months of structured interval training.
A higher score means better endurance, greater energy in daily life, and a lower risk of disease and early death. Even modest improvements in your VO₂ max can carry meaningful benefits.
But you don’t need to chase the high numbers of elite athletes. Focus on training consistently, challenging yourself by adding faster or longer intervals, or pushing for an extra mile. Your VO₂ max should increase with the accomplishment you feel as you hit your goals and improve your health on your fitness journey.