Here's the direct answer: VO2 max for women is the most useful fitness number you're probably not tracking — and it may matter more for your longevity than most of the labs on your annual panel. VO2 max is the maximum amount of oxygen your body can use during intense exercise. It's the gold-standard measure of cardiorespiratory fitness, and cardiorespiratory fitness is one of the strongest predictors we have of how long you'll live.
Heart disease is the leading cause of death in women — about 1 in 5 female deaths. Yet in routine women's preventive care, we measure cholesterol, blood pressure, and blood sugar, and almost never measure fitness itself. I find that strange, and the research backs me up.
What does VO2 max for women actually measure?
Think of oxygen as a delivery chain. Your lungs take it in, your heart pumps it out, your blood carries it, and your muscles spend it. VO2 max measures how well that entire chain performs at maximum effort — which means it reflects your heart, your lungs, your circulation, and your muscle all at once.
That's why it predicts so much. A single cholesterol value tells you about one pathway. VO2 max tells you about the integrated capacity of the systems that keep you alive. When it declines, it's rarely one thing failing — it's the whole system quietly losing capacity, often years before symptoms show up.
What does the research say about fitness and longevity?
This is one of the most consistent findings in all of preventive medicine.
In a large clinical cohort study of roughly 122,000 patients who underwent exercise testing, low cardiorespiratory fitness carried a mortality risk comparable to — or greater than — smoking, diabetes, or existing heart disease. Read that again. Being unfit was as dangerous as the conditions we organize entire screening programs around. The same study found no upper limit to the benefit: the fittest patients kept doing better, with no ceiling where extra fitness stopped helping.
A meta-analysis of the fitness literature put a number on the dose: each 1-MET higher level of fitness was associated with about 13% lower risk of dying from any cause. A MET is simply a unit of energy expenditure — one MET is what you burn at rest. You don't need to become an athlete to gain a MET. For many women, going from sedentary to consistently active is enough to move that needle, and 13% is a bigger effect than many medications deliver.
This is why the American Heart Association has argued that cardiorespiratory fitness should be treated as a clinical vital sign — measured like blood pressure, not guessed at once a decade.
Why does women's heart risk accelerate after menopause?
Estrogen does quiet protective work on the cardiovascular system for decades — supporting blood vessel function and a friendlier lipid pattern. As estrogen declines through the menopause transition, that protection fades: lipids shift in the wrong direction, and cardiovascular risk climbs.
Here's the part I emphasize with patients: the risk doesn't start at menopause. It becomes visible then. The women who weather the transition best are the ones who built cardiovascular capacity before and during it — not the ones who start from zero at 55 with worse lipids and a decade of lost fitness behind them. Building that capacity in your 30s and 40s is precisely what female longevity medicine is designed around: measure the systems that age fastest in a woman's body, early, while they're most trainable.
How is VO2 max actually measured — and can your watch do it?
The true measurement is a cardiopulmonary exercise test, or CPET: you exercise at increasing intensity in a lab, wearing a mask that measures the oxygen you consume and the carbon dioxide you produce. That's the gold standard, and it's the number researchers use.
Your Apple Watch or Garmin gives you an estimate. These devices infer VO2 max from your heart rate and pace during outdoor workouts. That's genuinely useful — for trends. If your estimate is climbing over six months, your fitness is improving. If it's sliding, that's an early warning worth paying attention to. But an estimate is not a measurement, and it shouldn't be treated as a diagnosis. I've written before about what wearables actually measure, and the same principle applies here: wearables are excellent pattern-spotters and poor lab instruments. Use the watch to track direction; use real testing when a number is going to drive a decision.
How do you improve your VO2 max?
Fitness is trainable at any age, and the recipe is simpler than the fitness industry makes it sound. Two ingredients do most of the work:
1. A base of moderate-intensity work ("Zone 2"). This is steady effort at an intensity where you can still speak in short sentences — brisk incline walking, cycling, easy jogging. It builds the aerobic engine: the mitochondrial capacity that everything else rests on.
2. Short high-intensity intervals. The classic format is 4 × 4: four minutes of hard effort (you should not be able to chat), followed by a few minutes of easy recovery, repeated four times. This is the stimulus that pushes the top end of your capacity up.
Put together, two to three structured sessions a week — some Zone 2, one interval session — alongside resistance training covers it. The strength work matters too: muscle is where much of that oxygen gets used, and protecting muscle is its own longevity project for women.
And remember the dose-response from the research: modest gains matter. You are not training for a podium. Moving up one MET is associated with a meaningful drop in mortality risk, and that is an achievable goal for almost every woman I work with.
What's the bottom line?
If you track one fitness number for longevity, track this one. It sits at the top of the list of longevity markers I review with patients, because it captures something no blood test can: how your whole system performs under demand.
Just hold it the way a clinician should: trend it, don't worship a single reading. One test on one day is a snapshot. The direction over months and years — especially heading into the menopause transition — is the information that actually changes decisions.
Frequently asked questions
What is a good VO2 max for women?
There's no single magic number — values vary with age and naturally decline over time, so your result is best read against women your age, not against athletes. What the research shows is that higher is consistently better, with no ceiling where more fitness stopped helping, and each 1-MET improvement is associated with about 13% lower all-cause mortality risk. Improving your own number matters more than hitting someone else's.
Can my Apple Watch or Garmin measure my VO2 max accurately?
These devices estimate VO2 max from heart-rate and pace data — they don't measure oxygen consumption directly. The estimate is useful for tracking your trend over time, but it isn't a diagnosis. A cardiopulmonary exercise test (CPET) in a lab is the true measurement.
I'm not an athlete. Does VO2 max still matter for me?
Yes — arguably it matters most for you. The large cohort data linking fitness to survival came from everyday patients referred for exercise testing, not athletes, and low fitness carried risk comparable to smoking or diabetes. Fitness is trainable at any age, and modest gains deliver meaningful benefit.
How often should I check my VO2 max?
Think in trends, not snapshots. A wearable estimate reviewed every few months, or a formal test after a dedicated training block, tells you far more than obsessing over a single reading. Direction over time — especially through your 40s and the menopause transition — is what should guide decisions.
Does strength training improve VO2 max?
Interval work and Zone 2 training are the direct drivers of VO2 max, but resistance training belongs in the same program. Muscle is where oxygen gets used, and preserving muscle mass is independently important for women's metabolic health and longevity. The strongest plan trains both.
If you want help building a fitness and testing plan around your hormones, your labs, and your actual life, book a free 10-minute discovery call. I see patients across California by telehealth, and we'll map out where your numbers stand and what to do first.
— Dr. Rubaina Dang, ND
This article is general information only and is not medical advice. Talk with your own clinician before starting a new exercise program or acting on any test result.