VO2 max: what's average, what's good, and how to increase it

VO2 max is the fitness number your watch loves to announce and almost nobody knows what to do with. It goes up, you feel smug. It goes down, you blame the watch. Both reactions are about half right.

Here's the useful version: what VO2 max actually measures, what average VO2 max looks like by age and sex, how much you can realistically increase VO2 max, and which training does it. Spoiler: there's no single magic workout. It's mostly a lot of easy running plus a small, regular dose of very hard running, placed so it doesn't collide with your squats. That placement is easier to get right by hand with the rules below, or with an app that plans your runs and your lifts.

What is VO2 max?

VO2 max is the highest rate at which your body can take in and use oxygen during hard exercise. It's usually written in milliliters of oxygen per kilogram of body weight per minute (mL/kg/min). That "per kilogram" matters: two people with identical hearts and lungs but different body weights get different numbers.

It's measured properly in a lab. You run on a treadmill wearing a mask while the speed or incline climbs until you can't continue, and a gas analyzer measures how much oxygen you're using. Everything else, including the number on your wrist, is an estimate.

In heart rate terms, the efforts that push you toward VO2 max live at the top of the five-zone model we use across this blog. If you want those bands in beats per minute for your own max heart rate, calculate your heart rate zones first.

VO2 max is the size of the engine, not the whole car. Two runners with the same VO2 max can race very differently, because how much of that ceiling you can hold for a long time (which comes down to your threshold pace) and how economically you run matter just as much.

Average VO2 max by age and sex

The cleanest US reference data comes from the FRIEND registry: 7,783 lab treadmill tests with measured oxygen uptake, in adults aged 20 to 79 without cardiovascular disease (Kaminsky, Arena and Myers, 2015). These are the 50th-percentile values, in mL/kg/min, from the paper's percentile table:

The authors put the decline at roughly 10% per decade in this cohort. A 2022 update from the same registry, with more labs and more tests, put its treadmill standards 1.5 to 4.6 mL/kg/min lower than the 2015 ones (Kaminsky et al., 2022). So "average" moves depending on who got tested. Read the medians above as a rough middle, not a pass mark.

How to read your number: above the median for your age and sex is above average. Well above it is good. In the FRIEND percentile table, the top 10% of men in their 20s were above about 62 mL/kg/min and the top 10% of women in their 20s above about 51.

Is your watch's VO2 max accurate?

As a trend, it's useful. As an absolute number, be skeptical. In a 2026 study of 40 healthy adults, Apple Watch Series 10 underestimated lab-measured VO2 max by about 6 mL/kg/min on average, with wide limits of agreement, and correctly classified the FRIEND fitness percentile of only 5 participants (14%) (Lambe et al., 2026). The authors concluded the estimates had poor individual-level agreement.

So: watch the direction of your watch's number over months, on the same device. Don't use it to decide whether you're "elite".

How much can you increase VO2 max?

More than you'd expect if you're starting from the couch. Less than the internet promises if you've been training for years.

• ›Training works for almost everyone. A meta-analysis of 28 controlled trials in healthy adults aged 18 to 45 found that endurance training raised VO2 max by about 4.9 mL/kg/min compared with not exercising, and high-intensity interval training by about 5.5 (Milanović, Sporiš and Weston, 2015). Gains were larger in people with lower starting fitness and in longer interventions.
• ›Intervals have a small edge. In the same meta-analysis, interval training beat continuous endurance training by a small margin, about 1.2 mL/kg/min.
• ›Your genes have opinions. In the HERITAGE Family Study, 481 sedentary adults did the same 20-week program. The average gain was about 400 mL/min, but some people gained little or nothing while others gained more than a liter per minute, and the response clustered strongly in families (Bouchard et al., 1999).
• ›Harder, longer intervals may reach the "non-responders". A meta-analysis of interval studies lasting 6 to 13 weeks found an average gain of about 0.5 L/min, and a subset using longer intervals showed bigger changes with a marked response in every subject (Bacon et al., 2013).

Translation: if you're new, almost any consistent running will raise your VO2 max for a while. If you're experienced, you'll need deliberate hard work on top of a big base, and progress gets slower.

How to increase VO2 max: what actually works

The recipe is boring and effective: mostly easy, a little very hard, consistently, for months. Knowing what each heart rate zone does makes the split easy to keep honest.

1. A small dose of very hard work

The most-cited trial here is Helgerud et al. (2007). Forty moderately trained men trained three times a week for eight weeks, with total work matched across groups. The groups doing intervals at 90–95% of max heart rate, including the now-famous 4 × 4 minutes, improved VO2 max significantly more than the groups running at lactate threshold (85% of max) or long and slow (70% of max).

That's zone 5 work. Common VO2 max sessions, all after a proper warm-up:

If structured intervals feel like too much, start with speed play. Tempo vs intervals vs fartlek is really a question of which hard run your week needs, and a fartlek with a few longer, harder surges is a gentle on-ramp to proper VO2 max work.

How much: one VO2 max session a week is enough for most recreational runners. Two is the ceiling for nearly everyone, and only in a block where running is the priority.

2. A lot of easy work underneath it

The hard sessions only work if the rest of the week lets you recover from them. Well-trained endurance athletes tend to do about 80% of their sessions at low intensity and about 20% hard (Seiler, 2010). That easy volume isn't filler: in the Milanović meta-analysis above, plain endurance training produced a large VO2 max gain on its own.

If you're wondering what "easy" means in practice, the zone 2 guide covers how to find the number and why it feels so slow. Short version: you can talk in full sentences.

3. Stop running everything in the middle

Most people who say their VO2 max is "stuck" run every session at the same moderately hard pace. That's too hard to recover from and too easy to push the ceiling. Make the easy days easier and the hard days genuinely hard, and the number usually starts moving again.

Does VO2 max matter for your race?

It matters more the shorter the race. A 5K is run close to your aerobic ceiling, so raising that ceiling tends to show up quickly there. If you want context for where your own times sit, average 5K times by age and sex are a more useful benchmark than a watch estimate.

For a half or full marathon, threshold and economy carry more weight, and VO2 max work becomes a supporting act. For Hyrox and other hybrid events, a bigger engine helps you recover between stations, but the strength work and the running base matter at least as much.

VO2 max training for people who lift

VO2 max sessions are hard days. Count them in the same fatigue budget as heavy squats and deadlifts.

• ›Don't run intervals the day after heavy lower-body work, or the day before.
• ›If you must double up, pair intervals with upper-body lifting.
• ›Low-impact options (bike, rower, ski erg) work for VO2 max intervals too, and they're kinder to legs that squatted yesterday.

Common VO2 max mistakes

• ›Chasing the watch number. A device estimate can move with your pace data, heat and sleep. Judge progress by race times and the paces you can hold in workouts.
• ›Racing every interval. If the last rep is a death march, you started too fast.
• ›Skipping the easy base. Intervals on top of nothing burn out fast.

How exrsz handles VO2 max training

exrsz builds a periodized plan from your goal, schedule, level and equipment, with VO2 max intervals placed in the phases where they matter and easy running underneath them. It balances those hard sessions against your lifting in one plan, adapts each week to how you actually trained, and reshuffles missed sessions so two hard days don't end up back to back.

FAQ

What is the average VO2 max?

In the US FRIEND lab data, the median was 48.0 mL/kg/min for men and 37.6 for women in their 20s, falling to 32.6 and 23.4 in their 50s (Kaminsky, Arena and Myers, 2015). It declines with age, roughly 10% per decade in that cohort.

What is a good VO2 max?

Anything above the median for your age and sex is above average. In the FRIEND data, the top 10% of men in their 20s were above about 62 mL/kg/min and the top 10% of women in their 20s above about 51 (Kaminsky, Arena and Myers, 2015).

How long does it take to increase VO2 max?

Most training studies show measurable gains within 6 to 13 weeks, with bigger gains for less-fit people and longer programs (Milanović, Sporiš and Weston, 2015). Plan to judge progress over a training block, not a fortnight.

Can you increase VO2 max with zone 2 training alone?

Yes, especially if you're starting out: continuous endurance training produced a large average gain versus no exercise in a meta-analysis of 28 trials, with intervals adding a small extra benefit (Milanović, Sporiš and Weston, 2015). Experienced runners usually need some zone 5 work to keep improving.

Is my watch's VO2 max accurate?

Not very, for an individual. One 2026 study found Apple Watch Series 10 underestimated lab VO2 max by about 6 mL/kg/min on average with wide error (Lambe et al., 2026), so use the trend, not the absolute number.