VO2 Max: What It Is, Why It Matters, and How to Improve Yours

VO2 max is one of the most frequently cited metrics in endurance sport. Garmin watches estimate it, coaches reference it, and athletes compare values as a proxy for fitness. But what it actually represents, and what its limitations are, is less well understood than the number itself.

This post explains what VO2 max measures, how it relates to race performance, and how to structure training to develop it effectively.

What VO2 Max Actually Measures

VO2 max is the maximum volume of oxygen your body can consume and utilise per minute, expressed relative to body weight in millilitres per kilogram per minute (ml/kg/min). It is the upper ceiling of your aerobic energy system; the maximum rate at which your heart, lungs, and muscles can work together to produce energy aerobically.

A higher VO2 max means the body can sustain faster aerobic paces before reaching the oxygen consumption ceiling. Elite marathon runners typically have VO2 max values above 70 ml/kg/min. Recreational runners typically range from 35 to 55. Untrained adults typically sit below 35.

VO2 max is significantly influenced by genetics; some athletes are born with cardiovascular architecture that allows for very high maximal oxygen uptake. Training can improve VO2 max substantially, but the ceiling is partly predetermined by physiology.

Why VO2 Max Is Not the Whole Story

VO2 max is a ceiling, not a performance predictor. Two athletes with the same VO2 max can have very different race performances depending on what fraction of that ceiling they can sustain over a given distance (their lactate threshold) and how efficiently they use oxygen at any given pace (their running economy).

This is why elite marathon runners like Eliud Kipchoge do not necessarily have the highest VO2 max values in the sport. Their performance is enabled by an exceptional combination of high VO2 max, very high lactate threshold as a fraction of VO2 max, and outstanding running economy.

For most amateur athletes, the most impactful training focus is not maximising VO2 max but improving lactate threshold and running economy. VO2 max training is valuable, but it is most effective when placed on top of a developed aerobic base, not substituted for it.

How VO2 Max Intervals Work

Training at or near VO2 max pace, the pace you could sustain for approximately 6 to 10 minutes of maximal effort, forces the cardiovascular system to function at its upper limit. With consistent exposure to this stimulus over weeks and months, the system adapts: stroke volume increases, cardiac output improves, and the ceiling of maximal oxygen consumption rises.

The most effective VO2 max sessions use intervals long enough to fully stress the aerobic system, typically three to five minutes per repetition, with recovery periods that allow partial recovery but maintain the elevated cardiovascular demand. Common formats include 5 × 1,000m, 6 × 800m, or 4 × 1,200m, each at an effort equivalent to 5k race pace.

How Often Should You Train VO2 Max?

VO2 max intervals are highly demanding and require significant recovery. For most amateur athletes, one VO2 max session per week is appropriate during the specific preparation phase of a training block. Two sessions per week is appropriate only for athletes with a very solid base and adequate recovery resources.

VO2 max training should not begin until aerobic base fitness and lactate threshold have been developed. Starting VO2 max intervals on an underdeveloped base produces fitness that is brittle and injuries that are predictable. The sequence, base, threshold, VO2 max, matters.

What Your Watch's VO2 Max Estimate Actually Tells You

Garmin, Polar, Apple Watch, and most GPS devices now provide VO2 max estimates derived from heart rate and pace data during runs. These estimates are useful for tracking trends but are not accurate absolute values. They can be significantly inflated or deflated by measurement conditions, pacing, and the quality of heart rate data.

Use your device's VO2 max estimate as a directional indicator; is it trending up, staying stable, or declining? This beats comparing it to other athletes or treating it as a precise physiological measurement.

Key Takeaways

VO2 max is an important component of endurance performance, but it is one factor among several. Build your aerobic base, develop your lactate threshold, and introduce VO2 max training at the right point in your training cycle. A well-structured training programme will develop all three in the right sequence, and the results will be measurable not just in estimated scores but in actual race performances.

Steve Barbour is a UK-based online running and triathlon coach. Explore coaching at stevebarbour.com/coaching. Free calculators at endurancetoolkit.com.