What VO2max is
VO2max is the highest rate at which your body can take up and use oxygen during exercise, expressed in millilitres per kilogram of body weight per minute. It is the ceiling of your aerobic engine: lungs, heart, blood, capillaries and mitochondria all contribute, which is why a single number summarises so much. A sedentary 50-year-old man might measure 30; a trained one 45; an elite endurance athlete 70 or more. It declines roughly 10% per decade from the thirties if nothing is done — and considerably less if something is.
One MET (metabolic equivalent) is 3.5 mL/kg/min, the oxygen cost of sitting still. Cardiology papers often report fitness in METs; a VO2max of 35 is 10 METs.
The evidence
The study most people cite is Mandsager et al. 2018 in JAMA Network Open: 122,007 patients at the Cleveland Clinic who had a treadmill test between 1991 and 2014, followed for a median of 8.4 years. Fitness was grouped by age- and sex-adjusted percentile: low (below 25th), below average, above average, high (75th–97.6th) and elite (above 97.7th). The findings:
- Mortality fell with every step up in fitness, with no plateau — the elite group did better than the high group, which is unusual for a risk factor.
- Low fitness versus elite: an adjusted hazard ratio of about 5. Being in the bottom quartile carried a higher risk than smoking, diabetes or coronary disease in the same model.
- Moving from low to below-average fitness — the smallest possible step — was associated with roughly a halving of mortality risk. The biggest gains go to the least fit.
That is one study, but it is consistent with everything before it. Myers et al. 2002 (NEJM, 6,213 men) found each extra MET of capacity was associated with a 12% lower mortality, in men with and without heart disease. Kokkinos has reported the same gradient in veterans, Blair in the Aerobics Center Longitudinal Study, and a 2022 analysis of 750,000 US veterans found the gradient held at every age up to the nineties. Cardiorespiratory fitness is, by a wide margin, the strongest single predictor of all-cause mortality we have.
The honest caveat is that these are cohorts: fit people differ from unfit people in many ways, and no trial has randomised people to high fitness for thirty years. The closest is Generation 100 (Stensvold 2020, BMJ): 1,567 Norwegians aged 70–77 randomised to five years of high-intensity intervals, moderate continuous training or general advice. Mortality was low in all three arms and not statistically different, though the interval group had the fewest deaths and the best fitness. Five years in healthy seventy-year-olds was too short to settle it; the direction was as expected.
How to test it
| Method | Accuracy | Cost and effort | Best for |
|---|---|---|---|
| Laboratory CPET (gas analysis, treadmill or bike to exhaustion) | Gold standard | Sports-medicine clinic or university; 30 minutes; the most expensive option | A true baseline and a yearly repeat; also gives your lactate and ventilatory thresholds for zone setting. |
| Cooper 12-minute run | Good, within ~5% in trained people | A track and a watch | Runners. Distance in metres: VO2max ≈ (distance − 505) / 45. |
| Rockport 1-mile walk | Fair | Flat course, heart-rate monitor | Older or less fit adults; uses time and finishing heart rate. |
| Watch estimate (Garmin, Apple, Polar) | Within about 10% once calibrated with outdoor runs or rides | Free with the device | Tracking the trend month to month. Do not compare brands. |
| Beep test / 20 m shuttle | Good | A hall and the audio | Team-sport people. |
Whichever test you choose, keep using it. A watch trend over a year tells you more than one laboratory number that is never repeated.
How to raise it
The Norwegian 4x4
The protocol with the best evidence for raising VO2max quickly is the one studied by Helgerud and colleagues at NTNU in Trondheim (2007, Medicine & Science in Sports & Exercise): four intervals of four minutes at 85–95% of maximum heart rate, separated by three minutes of easy movement, three times a week. In eight weeks it raised VO2max by about 7% in trained young men, versus roughly 5% for shorter 15-second intervals and almost nothing for long, slow distance at the same total work. The same group used the protocol in the Generation 100 trial.
It is hard. Four minutes at 90% of maximum feels like a sustained climb you are not sure you can hold; the last minute of the fourth interval is the point. Once a week is enough for most people once a base is built; twice is plenty.
Zone 2
Zone 2 is steady aerobic work at a pace you could hold a conversation at, roughly 60–70% of maximum heart rate or just below the first lactate threshold. It does not raise VO2max as fast as intervals, but it builds the mitochondrial density, capillaries and fat oxidation that intervals sit on, it can be done often, and it is where most of the training volume of every endurance athlete lives. The usual recommendation for a healthy adult is 150–180 minutes a week in three or four sessions, on a bike, a rower, a brisk incline walk or an easy run.
The week that works
| Level | Zone 2 | Intervals | Expected 12-week gain |
|---|---|---|---|
| Sedentary, any age | 3 × 30–40 min | None for the first 4–6 weeks, then 1 × 4x4 at 85% | 10–20%. The least fit gain the most, and the mortality curve is steepest here. |
| Recreationally active | 3 × 45 min | 1 × 4x4 | 5–10%. |
| Trained | 4 × 60 min or more | 1–2 × 4x4 or 30/30s | 2–5%; gains slow near the ceiling. |
| Over 65 | 3–4 × 30–45 min, incline walking counts | 1 × 4x4 at 80–85% once cleared by a physician | 8–15%; Generation 100 showed it is safe and effective at this age. |
Realistic gains in a year: a sedentary 50-year-old starting at 30 can reach 36–38 with consistent work — two fitness bands up in the Cleveland Clinic model, which is where most of the risk reduction lives. Beyond that the gains are slower and the point becomes holding the number against the decade.
What to measure
- VO2max once a year by the same method, plus the watch trend.
- Resting heart rate and heart-rate variability from a wearable: both improve with aerobic base and are an early sign of over-reaching when they go the wrong way.
- Pace or power at a fixed heart rate in zone 2 — the most practical month-to-month marker. Same route, same heart rate, faster is fitter.
- Ferritin and haemoglobin, because low iron caps VO2max and is common in endurance training, in women especially.
- Blood pressure and HbA1c, which usually improve alongside and confirm the work is real.
Where peptides and therapies fit
Nothing in the research library raises VO2max. What some of the compounds are studied for is making the training possible: sleep and recovery, which is why the sleep goal page is the one most endurance people need first, and tissue repair when a tendon or a joint is the thing keeping someone off the bike — the Wolverine combination is the page for that. MOTS-c is interesting here because it raised exercise capacity in mice, but there is no human trial of it for fitness, and the article on mitochondria says why exercise remains the lever. Among therapies, sauna has small trials showing plasma volume and endurance gains in trained people; it is a complement, not a substitute.
Common mistakes
- All intervals, no base. Three 4x4 sessions a week without zone 2 stalls within months and breaks down tendons.
- All base, no intervals. Zone 2 alone raises VO2max slowly in people who are already active; one hard session a week is the missing piece.
- Zone 2 too hard. If you cannot talk, it is zone 3, which is tiring and not what the base is built from. Use a heart-rate cap, not feel, for the first months.
- Testing on a different device each time and worrying about the difference.
- Ignoring iron. A ferritin under 30 will cap any programme, and endurance training drives it down.
- Starting intervals at 60 without clearance. The trials screened people; a treadmill test with a physician is the sensible way in.
Frequently asked questions
What is a good VO2max for my age?
Roughly: top 25% for your age and sex is the sensible target, which for a 50-year-old man is above about 40 mL/kg/min and for a 50-year-old woman above about 32. The Cleveland Clinic data show benefit at every step up, with no ceiling, so "good" is always "a little higher than now".
How much does VO2max really affect lifespan?
In 122,007 patients followed for over eight years, the least fit quartile had about five times the mortality of the fittest group, a bigger difference than smoking or diabetes. Each extra MET of fitness is associated with roughly 12% lower mortality in several cohorts.
What is the Norwegian 4x4?
Four intervals of four minutes at 85–95% of maximum heart rate with three minutes of easy recovery between them, studied by Helgerud at NTNU. It raised VO2max about 7% in eight weeks and was the protocol used in the five-year Generation 100 trial in 70-year-olds.
Is zone 2 enough on its own?
For a sedentary person, yes for the first months — any steady aerobic work raises fitness quickly from a low base. For someone already active, zone 2 alone plateaus; adding one interval session a week is what moves the number again.
Can I measure VO2max without a laboratory?
Yes. The Cooper 12-minute run and the Rockport walk are validated field tests, and a sports watch estimates it within about 10% once calibrated. Use the same method each time and follow the trend; book a laboratory test for a true baseline if you can.
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