VO2max for runners: what it is, how to estimate it and how to raise it

Your watch shows a VO2max number — what does it mean? How VO2max is estimated, what's a good score, the workouts that improve it, and why Bangkok's heat lowers your reading.

Updated · 6 min read

VO2max has gone from lab jargon to a number on every runner's watch. It's a useful measure of aerobic fitness — as long as you know what it can and can't tell you.

What VO2max means

VO2max is the most oxygen your body can use per minute during hard exercise, measured in millilitres per kilogram of body weight (ml/kg/min). A higher number means a bigger aerobic engine. It's one of three things that decide race performance, alongside running economy (how efficiently you move) and threshold (how much of your VO2max you can hold for a long time).

How to estimate yours

  • From a race: the most useful for runners. A recent all-out 5K or 10K gives your VDOT — a performance-based VO2max — plus matching training paces.
  • Cooper 12-minute test: run as far as you can in 12 minutes on a track.
  • Heart rate: a rough estimate from your resting and maximum heart rate.
  • Your watch: uses heart rate and pace on your runs. Handy for trends, but it can drift with heat, a loose strap or GPS errors.

What's a good VO2max?

It depends heavily on age and sex, and on genetics. Many recreational runners are in the 40s, well-trained club runners often in the 50s, and elite distance runners in the 70s or higher. It naturally declines with age, but training slows that a lot. The most useful comparison is with your own number a few months ago.

How to raise it

  • A big aerobic base. Plenty of easy running — see our Zone 2 guide — is the foundation.
  • VO2max intervals, once or twice a week: for example 5 × 3 minutes hard with 3 minutes easy jogging, or 6 × 800 m on a track. Hard, but controlled — you should finish the last rep as strong as the first.
  • Hill repeats: 6–10 × 60–90 seconds uphill. Bangkok is flat, but bridges and the ramps on the Green Mile work.
  • Consistency: most recreational runners see gains of around 5–10% in the first 2–3 months of structured training.

Why your VO2max drops in Bangkok

If your watch's VO2max dips after a few weeks in Bangkok, don't panic. Heat raises your heart rate at any pace, and most watches read that as lower fitness. Races run in the heat also give a lower VDOT than the same effort in cool weather. Use your best cool-season results, run your hard sessions early in the morning, and check the heat pace calculator to set realistic targets.