How accurate are VO2 max estimates from sports watches?

Good enough for the trend, too imprecise for the absolute figure: watches estimate it from pace-to-heart-rate ratios and can be noticeably off compared with a lab measurement – but the direction over months is usually right. As with all wearable data, the practical approach is: watch your own trajectory, don't compare the single number against tables or other people. More on the reliability of these estimates in our wearables article.

Can I still improve my VO2 max at any age?

Yes – trainability remains intact for life, even though the starting value declines with age (roughly ten per cent per decade from 30 onwards in untrained people). Studies show clear gains even in people in their late sixties and beyond. That's exactly why building it up early pays off twice over: going into old age with a high baseline gives you reserve – starting late still delivers gains. (Have any pre-existing conditions checked by a doctor first.)

Can a low VO2 max value be dangerous?

A low value alone isn't a diagnosis, but it is a signal worth taking seriously – especially combined with breathlessness during everyday exertion, chest pain, or a sharp drop in performance compared with before. In these cases, a medical check-up belongs before the training plan, not after. This article is not a substitute for medical advice.

How quickly does VO2 max improve with training?

For most untrained people, the first measurable improvements show up after four to eight weeks of consistent training, with noticeable jumps often after eight to twelve weeks. The speed depends heavily on your starting point: someone starting from zero improves faster initially than someone already trained – the room for improvement shrinks as fitness level rises.

Is VO2 max more important than strength training for life expectancy?

It's not an either-or: both are among the best-evidenced longevity levers, but they act on different risks – VO2 max mainly on cardiovascular mortality, strength training additionally on muscle mass, bone density and fall risk in old age (more in our strength training article). Anyone forced to pick just one would be giving up part of the benefit.

Travel & Lifestyle · Longevity

VO2 Max: The Most Important Number You Don't Know

VO2 max predicts life expectancy better than cholesterol or blood pressure. How to estimate it without a lab, what it means, and the training that raises it.

By Boaz Lichtenstein

Article image: VO2 Max: The Most Important Number You Don't Know

Imagine a lab value that predicts your odds of living through the next few decades better than cholesterol, blood pressure or blood sugar – and that nobody measures at a check-up anyway. That value exists: VO2 max, the maximum amount of oxygen your body can take up and use per minute. In large cohort studies, it’s one of the strongest known predictors of all-cause mortality – the gap between low and high fitness outstrips the effect of most classic risk factors.

Key takeaways

VO2 max measures how much oxygen your body can maximally take up and use – a whole-system test for lungs, heart and muscles in a single number.
The value is one of the strongest known predictors of life expectancy, stronger than many classic risk factors.
Without a lab, you can roughly estimate it using a sports watch, the Cooper test, or simple everyday questions.
The most effective training combination: a broad aerobic base (Zone 2) plus weekly high-intensity intervals.
Improvements remain possible for life – even starting late, training still pays off substantially.

Why this particular number matters

VO2 max is a whole-system test packed into one figure: lungs, heart, blood, blood vessels and muscles all have to work together to get oxygen from a breath into a mitochondrion. That’s why the value captures the overall state of the cardiovascular system like no single parameter can – and why a higher VO2 max doesn’t just mean statistical years of life, it means concrete reserve: the staircase that becomes a hurdle at 80 for one person is just an ordinary day for another, and pushes them to their limit.

Ageing relentlessly lowers the value – anyone who starts high and slows the decline stays above the threshold where independence starts to slip for longer. That’s exactly where the real lever lies: it’s less about your athletic best at 30 and more about still being able to climb stairs, go shopping and travel independently at 70.

The comparison with other check-up values makes the difference tangible: blood pressure and cholesterol say something about individual risk factors, while VO2 max says something about the actual functional capacity of the whole system under load. Two people with identical blood values can differ hugely in VO2 max – and that gap explains a substantial part of the difference in how fit both actually feel day to day, and how much they can actually handle.

Roughly placing your VO2 max value

Absolute values depend heavily on age, sex and training status – as a rough guide, four categories can be distinguished, without needing to match a single number against an online table.

Category	Rough placement	Typical trait
Low	bottom fitness fifth of the age group	everyday exertion is already tiring
Average	middle of the age group	normal everyday resilience
Good	top third of the age group	reserve for more intense exertion
Very good/trained	top fifth, usually with regular endurance training	clear reserve, slower age-related decline

More important than the exact category is the direction: a value that stays stable or rises over years beats any single snapshot – and you can track your own progress well without a lab, just from trends on a sports watch, the Cooper test, or how you feel day to day.

A notable pattern in the research: the jump from “low” to “average” usually brings the biggest gain in life expectancy – anyone climbing out of the bottom fitness fifth gains more, statistically, than someone moving from “good” to “very good”. That’s good news for beginners: the biggest lever isn’t at the top of the scale, it’s right at the start of the journey.

Measuring and placing it – without a lab

The gold standard is cardiopulmonary exercise testing (a mask test with a sports physician, worth it for anyone who wants to know precisely). For everyday purposes, approximations are enough: sports watches estimate the value continuously – useful as a trend, not as an absolute figure. The Cooper test (maximum distance covered running for twelve minutes) offers a proven rough formula. And the simplest self-assessment is functional: how many flights of stairs can you climb briskly without stopping?

What matters is less the precision than the direction – the value should rise or hold over years, not get measured obsessively every day. If you repeat the Cooper test regularly, do it under comparable conditions (same route, similar weather, well-rested), otherwise external factors will dilute the result more than actual fitness progress does.

From experience: a simple everyday test with no equipment at all is the stair test – climb four flights briskly but under control. If you’re noticeably out of breath or need a break, you’re likely on the lower end; if you could still hold a conversation, you’re likely on the higher end. No substitute for an actual measurement, but a free first data point you can repeat every few months.

The training that raises it

The recipe is well documented and unspectacular: a broad aerobic base – Zone 2 training from our sport chapter, two to four hours a week – plus targeted high-intensity stimuli that push the system to its ceiling: once a week, intervals, classically around four times four minutes hard with active recovery in between.

The base widens the foundation, the intervals raise the ceiling; each component works on its own, but the combination works best. It’s the same pattern as everywhere else in longevity evidence: no secret, no product – just a value that responds to consistent, patient training, paid in the most reliable currency there is: healthy years.

For getting started, a simple weekly plan is enough: two to three easy Zone 2 sessions of 30 to 60 minutes each, plus once a week four intervals of four minutes hard with three to four minutes of active recovery in between. If you’re completely untrained, start with shorter, less intense intervals and build up volume and intensity over several weeks – the body needs time to adapt to the new load before the full dose makes sense.

The most common mistakes in VO2 max training

Training at only one intensity: running at the same medium pace all the time (neither easy nor hard) wastes both effects – the aerobic base barely grows, and neither does the ceiling.
Too many intense sessions: more than one or two hard interval sessions a week tend to raise injury and overtraining risk rather than lift VO2 max faster.
Impatience: giving up after two weeks with no visible difference means stopping right before the point where the first effects typically appear.
Skipping strength training entirely: muscle mass indirectly supports oxygen utilisation – training endurance alone leaves some of the potential on the table (see strength training after 40).
Ignoring pre-existing conditions: anyone who hasn’t trained in a while or carries risk factors should get medical clearance before intense intervals.

The bottom line

VO2 max is the rare case of a health value you can improve directly, demonstrably and within a manageable timeframe – no supplement, no expensive gadget, just consistent repetition. If you’ve never measured where you stand, the easiest start is the Cooper test, the stair test or a sports watch, followed by eight to twelve weeks of training in the Zone 2-plus-intervals pattern. The next measurement then shows, in black and white, what’s changed – usually more than most people think possible at the start. And even if you never measure a single value, you still benefit from exactly the training that drives the number up: the real goal was never the number itself, but the stairs, suitcases and trips it still makes possible in old age.