Is Your VO₂max Truly a Good Performance Indicator?

Ever since our GPS watches started displaying VO₂max estimates, this number has become a bit of an obsession for many of us. A high VO₂max is associated with performance, cardiovascular health, and even longevity. But does this single metric truly tell the whole story? Spoiler alert: not quite.

What Exactly Is VO₂max?

VO₂max is the maximum amount of oxygen your body can utilize per minute per kilogram, expressed in ml/kg/min. Essentially, it represents the power of your aerobic engine. To measure it accurately, a lab test with gas analysis is required — otherwise, you're relying on your watch's estimates or field tests.

Typical values: 30-40 ml/kg/min for a sedentary adult, 70-85+ for elites. The relationship between VO₂max and MAS (Maximum Aerobic Speed) allows you to convert between the two and fine-tune your training.

Why It's a Good Indicator

For Groups of Runners

Across a large group of runners, VO₂max is an excellent predictor of performance. Runners with a VO₂max of 65 are almost always faster than those at 50. The correlation with 5K, 10K, and half marathon times is strong — typically in the range of r = 0.8 to 0.9.

As a Health Indicator

From a health perspective, VO₂max is arguably the best predictor of all-cause mortality we have. A high VO₂max for your age is associated with a significantly reduced cardiovascular risk. Even a modest gain (going from 35 to 40) has a substantial impact on longevity.

Why It's a Limited Indicator

The Elite Runner Paradox

Among elite runners, VO₂max alone no longer dictates performance differences. Two world-class marathoners might have the same VO₂max (80 ml/kg/min) but be separated by 5 minutes in a marathon. Why? Because beyond a certain level, other factors come into play:

• Running Economy — how much oxygen you consume at a given pace. Two runners with the same VO₂max but different running economies will yield different performances.
• Lactate Threshold — the percentage of your VO₂max you can sustain for the duration of a race. A runner who utilizes 85% of their VO₂max at their lactate threshold will be faster than another at 75%.
• Fatigue Resistance — your ability to maintain good running economy even as your muscles start to fatigue.

Watch Estimates Are Approximate

The VO₂max displayed by your watch is an estimate based on your heart rate and pace — not a direct measurement. It can vary by ±5 ml/kg/min compared to lab results. Heat, terrain, fatigue, caffeine, stress: all influence your heart rate and, consequently, the estimation. Tracking your VO₂max daily doesn't make much sense; however, the trend over several months is insightful.

What Complementary Indicators Are There?

Your MAS (Maximum Aerobic Speed) provides a practical translation of VO₂max into running speed. Race times estimated from your MAS are often more useful than a raw VO₂max number for planning your training. Estimating race times from recent performances is even better because it integrates all factors — not just VO₂max.

Personally, I find that the best data to track your progress remains your actual race performances: 5K, 10K, or half marathon times under comparable conditions. A 10K in 42 minutes in March and 40 minutes in October tells you more about your fitness than any VO₂max number.