For a woman aged 40 to 49, a VO2 max of 36.3 ml/kg/min or more puts you in the top 40% of your age group in the Cooper Institute norms, and 45.3 or more puts you in the top 5%. Most women never learn their number, yet in a Cleveland Clinic analysis of 122,007 people, low fitness carried a mortality risk comparable to or higher than smoking or diabetes. Below you get the full chart by age, a walk test you can do this week with a watch and a flat path, and an 8-week plan to move up a band.
Key takeaways
- VO2 max is how much oxygen your body can use per minute per kilo of body weight. Women are scored on their own scale, roughly 6 points lower than men’s at the same age and fitness band.
- In the Cooper Institute norms, “Good” for women is 37.8 in your 30s, 36.3 in your 40s, 33.0 in your 50s and 30.0 in your 60s.
- The gap between decades widens after 50, which is exactly when consistent training pays off most.
- You can estimate your number at home with the Rockport 1-mile (1.6 km) walk test. Your watch is useful for trends but can be off by several points.
- Two easy aerobic sessions, one interval session and two short strength sessions a week is a realistic structure. Retest at week 8 and judge the trend, not one reading.
What VO2 max means for a woman over 35
VO2 max is the maximum amount of oxygen your body can take in, deliver and use during hard exercise. It is measured in millilitres of oxygen per kilogram of body weight per minute (ml/kg/min), and it is the single best lab measure of aerobic fitness.
Think of it as the size of your engine. A bigger engine means climbing stairs, chasing a toddler or talking on a hill feels easier, because you are working at a smaller fraction of your maximum.
Women’s values run lower than men’s at every age, which is why you should never judge your number on a men’s chart. Women carry a higher percentage of body fat on average and less haemoglobin in each litre of blood, so the oxygen delivered per kilo is lower even when fitness is identical. In the Cooper Institute norms below, “Good” at 40 to 49 is 36.3 for women and 42.4 for men.
If you want the broader background, including how the number is measured in a lab, read our guide to VO2 max after 35 and how to raise it. This article focuses on what the women’s chart says and what to do with it.
VO2 max for women by age: the chart
The table below is the women’s VO2 max classification published by The Cooper Institute, the Dallas research centre whose fitness norms are used by sports watches and many exercise physiology labs. Values are in ml/kg/min. Find your age row, then see which band your number falls into.
| Age | Poor | Fair (40th percentile) | Good (60th) | Excellent (80th) | Superior (95th) |
|---|---|---|---|---|---|
| 20–29 | Under 36.1 | 36.1 | 39.5 | 43.9 | 49.6 |
| 30–39 | Under 34.4 | 34.4 | 37.8 | 42.4 | 47.4 |
| 40–49 | Under 33.0 | 33.0 | 36.3 | 39.7 | 45.3 |
| 50–59 | Under 30.1 | 30.1 | 33.0 | 36.7 | 41.1 |
| 60–69 | Under 27.5 | 27.5 | 30.0 | 33.0 | 37.8 |
| 70–79 | Under 25.9 | 25.9 | 28.1 | 30.9 | 36.7 |
Source: The Cooper Institute women’s norms, as reprinted in Garmin’s VO2 max standard ratings (see Sources). The Cooper bands are one set of norms; the US FRIEND registry, built from 7,783 maximal treadmill tests at eight laboratories, is another. Use whichever your watch or lab uses, but do not mix them.
How to read your number
Each column is the value at that percentile. So a 44-year-old woman with a VO2 max of 38 sits above the 60th percentile (“Good”) but below the 80th (“Excellent”): fitter than roughly six in ten women her age.
A 52-year-old with 31 is in the “Fair” band, just above the 40th percentile. A 38-year-old with 43 is “Excellent”.
These bands are comparisons with other women, not health thresholds. A woman in the “Fair” band who trains consistently is doing far better for her future self than the label suggests, and the trend over months matters more than any single reading.
What the chart says about ageing
Look down the “Good” column: 37.8 in your 30s, 36.3 in your 40s, 33.0 in your 50s, 30.0 in your 60s. The step from the 30s to the 40s is only 1.5 points. The steps from the 40s to the 50s and from the 50s to the 60s are 3.3 and 3.0 points.
In other words, the population average drifts down slowly through your 40s and faster after 50. Those norms describe what typically happens to women, most of whom train very little. They do not describe what has to happen to you.
If you are in perimenopause and your usual pace suddenly feels harder, that is common and not a reason to stop; keep the easy sessions easy, and talk to your doctor if hot flushes or poor sleep are getting in the way of training.
Why your VO2 max matters more than your weight
In 2018, Cleveland Clinic researchers published an analysis in JAMA Network Open of 122,007 patients who had done a treadmill test between 1991 and 2014. Higher fitness was linked to lower long-term mortality at every level, with no upper limit to the benefit.
Two findings stand out for women over 35. First, low fitness carried a risk comparable to or higher than established risk factors such as diabetes and smoking. Second, the fittest group (the top 2.5% for their age and sex) had an 80% lower mortality risk than the least fit group.
This was an observational study, so it shows association rather than proof of cause. But the direction is consistent across decades of research: a higher VO2 max is one of the strongest things you can have on your side, and unlike your age it is something you can change.
How to estimate your VO2 max without a lab
A lab test with a mask is the gold standard, but you do not need one to get a useful estimate. Here are the two realistic options.
The Rockport 1-mile walk test (about 20 minutes)
This test was designed for ordinary adults, not athletes, and it only needs a flat, measured 1-mile (1.6 km) route, a watch and a heart rate reading. A 400 m running track is ideal: four laps plus 9 m. A GPS watch or a mapped path also works.
- Warm up with 5 to 10 minutes of gentle walking.
- Walk 1 mile (1.6 km) as fast as you can at an even pace. You must walk, not jog, or the formula no longer applies.
- Stop your timer at the finish and note your time in minutes and seconds.
- Immediately note your heart rate from your watch or chest strap, or count your pulse for 15 seconds and multiply by four.
Then put your numbers into the standard equation (weight in pounds: kg × 2.2; time in decimal minutes, so 15:30 is 15.5):
VO2 max = 132.853 − (0.0769 × weight in lb) − (0.3877 × age) + (6.315 × sex) − (3.2649 × time) − (0.1565 × heart rate), where sex = 0 for women and 1 for men.
Worked example: a 42-year-old woman weighing 68 kg (150 lb) walks the mile in 15:00 with a finishing heart rate of 140. Her estimate is 132.853 − 11.5 − 16.3 + 0 − 49.0 − 21.9 = about 34.2 ml/kg/min. On the chart, that is the “Fair” band for 40 to 49, a little above the 40th percentile and about 2 points short of “Good”.
Repeat the test on the same route, at the same time of day, every 8 weeks. The absolute number has a margin of error, but the change between tests is meaningful if conditions match.
What your watch is really telling you
Garmin, Apple, Polar and Fitbit watches estimate VO2 max from your pace and heart rate during runs or walks, then score you against the same Cooper Institute bands. That is convenient, and it is good for spotting a trend over months.
The absolute number deserves some scepticism. In a 2024 validation study published in JMIR Biomedical Engineering, the Apple Watch Series 7 underestimated lab-measured VO2 max by 4.5 ml/kg/min on average in 19 adults, with a mean error of about 16%. For the fittest participants the gap was 12 points, while the least fit were slightly overestimated. Garmin studies cited in the same paper reported errors under 10%.
The study was small, with only seven women, so treat it as a caution rather than a verdict. Practical rule: use your watch for direction, and give it several outdoor sessions with a steady heart rate signal before trusting the figure. If it says 33 and your walk test says 36, the truth is probably somewhere between, and both will move together if you train.
Where the walk test falls short
The Rockport equation was built on adults of mixed ages, and it loses accuracy at the edges. A 2009 Brazilian study of active women aged 70 to 79 found the test highly repeatable, but it underestimated measured VO2 max by about 9.5 ml/kg/min. For women in their late 30s to 50s it is a reasonable ballpark; for your mother, it is better used for tracking change than for placing her on the chart.
If you already run comfortably, the walk test will also understate you, because walking cannot push your heart rate high enough. Lean on your watch or a running-based estimate instead, and if you are new to running start with our guide to running after 35 for women.
How to improve your VO2 max: an 8-week plan
VO2 max responds to two kinds of work: lots of easy aerobic minutes, which build the capillaries and mitochondria in your muscles, and short hard efforts, which train your heart to pump more blood per beat. You need both, and after 35 you also need strength work so the extra cardio does not come at the expense of muscle and bone.
This plan fits in about three hours a week. “Easy” means you could speak in full sentences and mostly breathe through your nose; if you want to set it by heart rate, our zone 2 cardio guide for women explains how. “Hard” means you can say a few words but could not hold a conversation.
| Weeks | Easy cardio (2 sessions) | Interval session (1) | Strength (2 sessions) |
|---|---|---|---|
| 1–2 | 30 min brisk walk, cycle or swim | 6 × 1 min hard / 2 min easy, plus 10 min warm-up and cool-down | 25–30 min full body |
| 3–4 | 35 min | 6 × 2 min hard / 2 min easy | 25–30 min full body |
| 5–6 | 40 min | 5 × 3 min hard / 2 min easy | 25–30 min full body |
| 7–8 | 40–45 min | 4 × 4 min hard / 3 min easy; repeat your walk test at the end of week 8 | 25–30 min full body |
Making it work in real life
- Any mode counts for intervals: hills on a walk, a spin bike, a rowing machine, swimming lengths or running. Choose what your knees and your schedule allow.
- Put the interval session on the day you feel freshest, and never do two hard days back to back.
- Keep the easy days genuinely easy. The most common mistake is doing every session at a medium effort, which is too hard to recover from and too easy to drive adaptation.
- Strength does not need a gym. Two short sessions built on squats, hinges, pushes, pulls and carries are enough; our 3-day strength plan for women over 35 shows how to set them up.
- If you are always tired and your numbers stall despite training, low iron is a common and fixable cause in women, because iron is what carries oxygen in your blood. Ask your doctor for a check and read our piece on iron for women.
- After week 8, keep the same structure and lengthen the hard intervals or add a fifth easy session. Retest every 8 to 12 weeks, not every week.
Safety note: The walk test is submaximal, but the interval sessions are not. If you have a heart condition, high blood pressure, chest pain or dizziness with exertion, or you have not exercised in years, talk to your doctor before starting intervals. Stop any session if you feel chest pain, light-headed or unusually breathless, and build up over the eight weeks rather than jumping to week 7 on day one.
FAQ
What is a good VO2 max for a 40-year-old woman?
In the Cooper Institute norms, 36.3 ml/kg/min is “Good” (60th percentile) for women aged 40 to 49, 39.7 is “Excellent” and 45.3 is “Superior”. Below 33.0 is classed as “Poor”. A result in the mid-30s means you are around the middle of your age group with plenty of room to climb.
Is a VO2 max of 35 good for a woman?
It depends on your age. At 35 ml/kg/min you are just above “Fair” in your 30s, between “Fair” and “Good” in your 40s, between “Good” and “Excellent” in your 50s, and between “Excellent” and “Superior” in your 60s. The same number means something different in every decade, which is why the chart is by age.
How accurate is the VO2 max on my Apple Watch or Garmin?
Good enough for trends, not for a diagnosis. In a 2024 study the Apple Watch Series 7 read 4.5 ml/kg/min low on average, with bigger gaps for very fit people, and studies of Garmin devices cited in that paper reported errors under 10%. Treat the number as a moving estimate and compare it with a walk test every couple of months.
How fast can a woman over 40 improve her VO2 max?
Nobody can promise a number, because your starting point, consistency and sleep all matter. What the evidence does support is the method: easy aerobic volume plus one interval session a week, kept up for at least eight weeks before you judge the result. Retest on the same route and compare like with like.
Why is VO2 max lower in women than in men?
The number is expressed per kilogram of body weight, and women carry a higher proportion of body fat and less haemoglobin per litre of blood on average, so less oxygen is delivered per kilo. That is why women have their own chart. Compared with other women your age, your result means exactly what it says.
Free tool: Work out your easy-day heart rate range with our Zone 2 Heart Rate Calculator, and get a quick picture of where you stand overall with the Fitness Test.
Sources
- The Cooper Institute, reprinted by Garmin. VO2 Max Standard Ratings (women and men by age). Garmin Owner’s Manual.
- Cleveland Clinic. Better cardiorespiratory fitness correlates to a longer life (Mandsager K et al., JAMA Network Open). EurekAlert, 2018.
- Caserman P et al. Assessing the Accuracy of Smartwatch-Based Estimation of Maximum Oxygen Uptake Using the Apple Watch Series 7: Validation Study. JMIR Biomedical Engineering, 2024.
- Kaminsky LA, Arena R, Myers J. Reference Standards for Cardiorespiratory Fitness Measured With Cardiopulmonary Exercise Testing (FRIEND registry). Mayo Clinic Proceedings, 2015; summary at COSMED.
- Marques P. Validity and reliability of the one-mile walk test (Rockport Fitness Walk Test) among 70-to-79 year old women. Revista Brasileira de Cineantropometria e Desempenho Humano, 2009.
- RunBundle. Rockport Walk Test: protocol and VO2 max equation. RunBundle, accessed 2026.
This article is for general education and is not medical advice. Check with your doctor before starting a new training or nutrition plan, especially if you have a health condition.
