VO2 Max for Runners: What It Is, and How to Actually Improve It (From a 50-Something Who Swears He Doesn't Track It)
- Jul 31
- 9 min read
Updated: 4 days ago
The honest, science-backed guide to what VO2 max really tells you, how to raise it, and why the number on your watch isn't the number you think it is.
VO2 max is everywhere you look in running. Someone on my Instagram feed is banging on about it at least once a day. And, honestly? I'm not that bothered about it.
I don't look at the number in my Apple Health, especially not after a long hard run or a set of fast intervals. I don't obsess when it drops, as it did, dramatically, earlier this year when I was out the shoes for a couple of months after emergency surgery (not a running injury, thankfully). And I definitely don't punch the air when it ticks back up towards the 54, 55 it usually sits at.
Ok, you got me. I absolutely do track that metric.
Far closer than I'll ever admit. So let's talk about it properly. What it is, whether you can move it, how to measure it, and why your smartwatch might be quietly lying to you.
Quick answer
VO2 max is the maximum amount of oxygen your body can use during hard exercise, measured in ml/kg/min. Think of it as the size of your aerobic engine. A bigger engine gives you a higher ceiling to train against. Most recreational runners can improve theirs by around 5 to 20% over three to six months, mainly through interval training like 4 x 4-minute efforts. It's useful to know, but it isn't the whole story. Threshold and running economy matter just as much.
Contents
What is VO2 max?
VO2 max is the maximum amount of oxygen your body can take in and put to use when you're working flat out. It's measured in millilitres of oxygen per kilo of body weight per minute (ml/kg/min), which is a fancy way of letting you compare runners of all shapes and sizes fairly.
Think of it as the size of your aerobic engine. Oxygen goes in through the lungs, gets pumped round by the heart, and is delivered to the working muscles to release energy. Bigger engine, more oxygen per minute, more work you can do.
Common myth: that it's your lungs holding you back. For nearly all of us, it isn't. The real ceiling is how much oxygen-rich blood your heart can pump, your cardiac output. That's exactly why all those hard aerobic sessions, the ones that leave you gasping, are what nudge the number up. You're training the heart to be a bigger, stronger pump.
What's a good VO2 max, and what's mine?
For a bit of context, here's roughly where people land:
Untrained man: around 35 to 40 ml/kg/min
Untrained woman: around 27 to 31 ml/kg/min
Elite male distance runners: 70 to 85 (Kipchoge is reckoned to be around 78)
Elite female distance runners: roughly 60 to 75
VO2 max also declines with age, very roughly 1% a year, although consistent training slows that decline right down.
Now for my own confession. Over the past few years I've watched my number creep quietly upwards, settling somewhere around 53 to 55. For a 50-something bloke, that lands me in the "well fit" bracket, and I'll happily take it.
But here's the good bit. I once went for a proper, professional VO2 max test. That meant running at increasingly brutal paces on a treadmill, wearing a mask any fighter pilot would be proud of, trying to signal my RPE to the guys running the test, and holding out a finger for a drop of blood every few minutes. By the end I looked, and felt, absolutely wasted.
Then they told me they'd seen a 57 on the monitor. I perked up instantly and walked out of that building feeling like every superhero rolled into one. A long way off Kipchoge, but very tidy for a 50-something who likes a Krispy Kreme. (Hold onto that 57. It matters when we get to smartwatches.)
Why does VO2 max matter for runners?
A higher VO2 max means a higher ceiling to train against, more room to hold faster paces before you redline. As a baseline of your aerobic fitness, it's genuinely useful to know.
But here's the bit the hype merchants skip. VO2 max is not the whole story. Race performance actually comes down to three things working together:
VO2 max, your aerobic ceiling
Lactate threshold, the pace you can hold before your legs fill with concrete
Running economy, how much oxygen you burn at a given pace
Two runners with an identical VO2 max can finish a 10K minutes apart if one is more efficient. So the number tells you how big the engine is. It says nothing about how well you drive it. Plenty of runners get quicker for a whole season without their VO2 max shifting much at all. They've simply got more efficient and lifted their sustainable pace. Treat it as a signpost, not a scoreboard.
Can you actually improve your VO2 max?
Some, yes, but less than Instagram would have you believe, and it varies wildly from person to person.
Roughly half of your VO2 max is written into your genes. Give a room full of people the exact same training plan and some will improve loads while others barely budge. For a typical recreational runner training properly for the first time, a gain of somewhere around 5 to 20% over three to six months is realistic. The fitter you already are, the harder those gains are to come by, because you're closer to your own ceiling.
I've had a first-hand lesson in this. After emergency surgery earlier this year (not a running injury, thankfully) my number fell off a cliff, and I've spent months quietly rebuilding the engine with dialled-back long runs, easy miles, and Z2/Z3 climbs on the old rail trail. Watching it crawl back towards the 50s has been oddly satisfying. That's VO2 max doing exactly what it does: responding to consistent, structured training.
Are you working on your VO2 max?
Yes
No
How to improve your VO2 max: the best workouts
The single biggest driver is time spent at or near your max. You can't hold that intensity for long in one go, which is why intervals are the tool of choice. They let you rack up far more time at the top end across a session.
The gold-standard session is the classic 4 x 4: four reps of four minutes at around 90 to 95% of max heart rate (roughly 3K to 5K effort), with three minutes of easy jogging between. Study after study finds this style of longer, hard-but-controlled interval beats all-out sprints for lifting VO2 max. Shorter 30-seconds-hard / 30-seconds-easy sets work well too, and are a friendlier place to start.
A few ground rules:
Keep hard VO2 sessions to two, maybe three times a week, no more
Make sure the bulk of your weekly mileage stays genuinely easy
Build a base of consistent running before you pile on the speed
Add strength work and anything that sharpens your form and economy
My rolling 800s and interval mornings are exactly this stuff. The sessions where a certain cheeky coaching app keeps politely nagging me to slow down.
Following a structured plan with proper interval sessions will quietly improve your VO2max.
The easiest way to build your engine
It's no secret I love the Runna coaching app. Over the past couple of years I've handed thousands of runners an exclusive free trial, and you can grab one too.
As we've seen, improving your VO2 max is absolutely possible, but only if the runs are well structured. That's where Runna quietly shines. It gives me progressive long runs that push me at intervals throughout, and interval sessions, like last night's 800s, that have me working upper tempo and into threshold. Week by week it builds the engine so gradually you barely notice, until one day you glance at your VO2 max and, yes, punch the air.
Only a programme that watches you, monitors you, feeds back in the moment and adjusts as you move through it can pull that off. No printed-off ChatGPT plan is going to deliver any of that.
So if you fancy seeing what I keep raving about, use this link, https://web.runna.com/redeem?code=ANDY2, or download the app and pop in the code ANDY2. Then go and watch your own VO2 max climb.
How to measure your VO2 max
There are three realistic ways to get a number, from most to least accurate:
1. A lab test (the gold standard). The treadmill, the fighter-pilot mask, the finger-pricks, the whole wasted-at-the-end experience. It directly measures the oxygen you breathe in and the carbon dioxide you breathe out. Precise, but it costs you.
2. A field test. The Cooper test, run as far as you can in 12 minutes, lines up strongly with lab VO2 max, and you can do it on any track. Simple, free, and brutally honest.
3. A race-time estimate. Plug a recent, honest race time into a VDOT calculator and you'll get a practical fitness figure that already bakes in your running economy.
How accurate is VO2 max on a smartwatch (Apple Watch, Garmin)?
Which brings me back to that wrist. Every Garmin, Apple, Coros and Samsung now serves up a VO2 max estimate, and it's tempting to treat it as gospel. Don't.
These numbers come from secret algorithms crunching your heart rate against pace and GPS data from a hard run. The watch has never actually measured a single molecule of your oxygen. Independent research puts the real-world error somewhere around 5 to 10%. And here's the kicker: watches tend to overestimate VO2 max in less fit runners and underestimate it in fitter ones.
Which is exactly my story. My Apple Watch Ultra 3 has me at 53 to 55. The lab, with its mask and its blood tests, said 57. The watch was underselling me, precisely the pattern the studies predict for a well-trained runner.
So use the trend, not the number. If your watch shows a steady climb across a training block, that's genuinely worth celebrating. If it tells you you're bang on 54, treat that as "roughly thereabouts." And if you want a figure you can truly trust, book a lab test or go and run a Cooper. Don't hand that job to your wrist.
None of which will stop me glancing at mine after every hard run, mind. I'm only human.
Lace up, enjoy your miles, and try not to obsess over the number. (Do as I say, not as I do.)
Frequently asked questions
What is a good VO2 max for my age?
It depends on age and sex, but as a rough guide: untrained men sit around 35 to 40 ml/kg/min and untrained women around 27 to 31. Trained club runners are well above that, and elite distance runners reach 70 to 85. For a runner over 50, anything in the low-to-mid 50s is excellent.
How long does it take to improve your VO2 max?
Most recreational runners see meaningful gains within about eight to twelve weeks of structured training, with a realistic improvement of 5 to 20% over three to six months. The fitter you already are, the slower and smaller the gains.
What's the best workout to increase VO2 max?
The best-evidenced session is 4 x 4 minutes at around 90 to 95% of max heart rate (roughly 3K to 5K effort) with three minutes of easy recovery between reps. Shorter 30/30 intervals also work well and are gentler to start with.
Can you improve VO2 max after 50?
Yes. VO2 max naturally drifts down with age by roughly 1% a year, but consistent aerobic training slows that decline and can still push the number up. I rebuilt mine back into the 50s after surgery in my own fifties.
Is the VO2 max on my Apple Watch or Garmin accurate?
It's a useful estimate, not a precise measurement, with typical real-world error of around 5 to 10%. Watches tend to overestimate lower fitness levels and underestimate higher ones, so trust the long-term trend rather than the exact figure.
Does VO2 max actually make you a faster runner?
It sets your aerobic ceiling, but it doesn't act alone. Your lactate threshold and running economy determine how much of that ceiling you can actually use, which is why two runners with the same VO2 max can race very different times.
About the author
Andy Hood is an ultra and endurance runner, cancer survivor and advocate based in Westward Ho!, North Devon. He writes honest, practical training guides, gear reviews and race reports at runningwestwardho.co.uk, and is the founder of Check Ya Balls, menswear that starts conversations and saves lives.
When he's not rebuilding his engine on the local rail trail, he's usually running to raise awareness and funds for those affected by cancer (and occasionally to a Krispy Kreme).
Article contains affiliate links/codes, I may receive a commission if you purchase products or services from the companies listed, at no cost to you. This goes toward running this blog, bringing you interesting articles and supporting my fundraising for cancer charities with over £27,000 raised to date.
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