What is VO2 max?
VO2 max measures the maximum amount of oxygen your body can use during intense exercise. It's expressed in milliliters of oxygen per kilogram of body weight per minute (mL/kg/min). The higher your VO2 max, the more efficiently your heart, lungs, and muscles work together to fuel movement.
Think of it as your body's engine size. A bigger engine can do more work before it runs out of power. For a deeper look at the science, check out our full VO2 Max guide.
Why it matters for longevity
Of all the biomarkers researchers have studied, VO2 max may be the single strongest predictor of how long you'll live. Dr. Peter Attia has called it the most powerful longevity marker we have — and the data backs this up. A landmark study found that people in the bottom 25% of cardiorespiratory fitness had roughly a 5x higher risk of dying compared to those in the top 25%. That's a bigger risk difference than smoking.
The good news: VO2 max is trainable at any age. Even if you're starting from a low baseline, consistent training can move you into a healthier category within months.
What the numbers mean
VO2 max ranges are age- and sex-dependent, so there's no single "normal" number. As a rough guide for women:
- Below average: under 30 mL/kg/min
- Average: 30–37 mL/kg/min
- Good: 37–44 mL/kg/min
- Excellent: above 44 mL/kg/min
For men, these ranges are roughly 5–8 mL/kg/min higher. Values naturally decline with age — about 1% per year after 30 — but regular training slows this decline dramatically. The goal for longevity is to stay in the top 25th percentile for your age group.
What affects it
- Training: Cardiorespiratory fitness is the primary driver. Both endurance training and high-intensity interval training (HIIT) improve VO2 max, but through different mechanisms.
- Genetics: Your baseline is partly genetic, but training can improve VO2 max by 15–30% regardless of starting point.
- Age: VO2 max naturally declines with age, but fit individuals in their 60s can match or exceed unfit people in their 30s.
- Body composition: Because VO2 max is measured per kilogram of body weight, higher body fat lowers your score even if your heart and lungs are strong.
- Iron status: Low ferritin can limit oxygen delivery to muscles, particularly in women. Make sure your iron stores are adequate.
How to get tested
The gold standard is a graded exercise test in a lab, wearing a mask that measures gas exchange. This costs $150–$300 and is available at sports medicine clinics and some gyms. You can also get a solid estimate using our VO2 Max Estimator, which uses your age, resting heart rate, and activity level. Many fitness watches also estimate VO2 max, though accuracy varies.
How to improve it
- Build a Zone 2 base. Spend 3–4 sessions per week doing easy, conversational-pace cardio for 30–60 minutes. This builds mitochondrial density and fat-burning capacity. Use our Heart Rate Zone Calculator to find your Zone 2 range.
- Add HIIT sessions. One to two high-intensity interval sessions per week (like 4x4-minute efforts at 90–95% max heart rate) can significantly boost VO2 max within 8–12 weeks.
- Stay consistent. VO2 max responds to consistent training over months, not one-off workouts. Regularity matters more than intensity.
- Strength train. Muscle mass supports cardiovascular output. Combining strength and cardio produces better results than either alone.
- Track your progress. Check your Fitness Age to see how your cardiovascular fitness compares to population averages and monitor improvements over time.