In 2018, a landmark study of 122,000 people published in JAMA Network Open found that cardiorespiratory fitness — measured by VO2 max — was a stronger predictor of mortality than smoking, hypertension, diabetes, or coronary artery disease. The researchers concluded that low fitness should be treated as a major clinical risk factor. Yet most people have never had their VO2 max measured.
What Is VO2 Max?
VO2 max (maximal oxygen uptake) is the maximum rate at which your body can consume oxygen during intense, sustained exercise. It measures the efficiency of your heart, lungs, blood, and muscles working together as a system. The higher your VO2 max, the more aerobic capacity you have — and the lower your risk of cardiovascular disease, metabolic disease, and early death.
VO2 Max and Fitness Age
Your fitness age is the age at which your VO2 max would be considered average. A 45-year-old with a VO2 max typical of a 30-year-old has a fitness age 15 years younger than their chronological age. Conversely, sedentary individuals often have a fitness age 10–20 years older than their calendar age. Research from the Norwegian University of Science and Technology has shown that people with high fitness ages live significantly longer and with fewer chronic diseases.
What's a Good VO2 Max?
VO2 max is measured in mL/kg/min. Benchmarks for men aged 30–39:
- Excellent: above 49
- Good: 43–49
- Average: 36–42
- Below average: below 36
Women's values are typically 10–15% lower due to differences in haemoglobin concentration and body composition.
The Fastest Way to Improve VO2 Max
High-intensity interval training (HIIT) produces the largest improvements. A simple protocol: 4 minutes at 85–95% of maximum heart rate, repeated 4–6 times, twice per week. Within 6–8 weeks, most people see meaningful improvements. Zone 2 aerobic training (conversational pace for 30–60+ minutes) provides the complementary base and has its own independent longevity benefits.
