How long does it take to improve VO2 max?
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About 6 to 13 weeks of three sessions a week, the length of most training trials, for a change you can measure. Watches lag behind, so retest the same way after 8 to 12 weeks and ignore the week-to-week wobble.
People start a new plan, check their watch after two weeks, see nothing, and decide it isn’t working. Even when the body is changing, a two-week gain is smaller than the error of any watch or field test. Fitness builds like interest in a savings account, slowly and steadily, and you can drain it a lot faster than you fill it.
We’d plan in blocks of 8 to 12 weeks, with a test on day one and another at the end, and nothing in between.
What the trials found
| Study | Who | How long | Gain |
|---|---|---|---|
| Norwegian 4x4 trial, 2007 | 40 fit young men, three sessions a week | 8 weeks | 7.2 percent, 55.5 to 60.4 |
| Review of 37 interval studies, 2013 | Inactive or lightly active adults under 45 | 6 to 13 weeks | 0.51 liters a minute on average, 0.8 to 0.9 with longer intervals |
| HERITAGE, 1999 | 481 inactive adults | 20 weeks | About 0.4 liters a minute on average, from almost nothing to over 1 liter |
| Dallas men at 50, 2001 | 5 men | 6 months | 14 percent, 2.9 to 3.3 liters a minute |
A review of 28 trials found longer programs gave bigger gains, about 2 points more for steady training and 3 more for intervals.
Why your watch is slower still
A watch estimate needs qualifying workouts to update. Garmin’s manual says it needs a few runs to learn, and Apple Watch only learns from outdoor walks, runs and hikes. A 2022 review of 14 wearable studies put a meaningful change at 1.75 to 3.5 points, and a single watch can be off by more than that. That’s why a block of 8 to 12 weeks, retested the same way, gives a clearer answer than daily checks.
How far is your next group?
The tool below shows how many points you are from the next group for your age and sex, and how long that took the 4x4 group at their pace of about 0.9 percent a week. Here are a few examples from the US chart.
- A woman in her 30s at 28 is 0.3 points below the middle, about 2 weeks at that pace.
- A man in his 40s at 42 is 1 point below the top quarter, about 3 weeks.
- A man in his 50s at 33 is 3.3 points below the top quarter, about 12 weeks.
People respond very differently, so treat those as a guide. If you’ve had no change after 12 weeks, make the hard sessions longer or more frequent.
Losing it is faster
When trained people stopped completely, VO2 max fell 7 percent in three weeks and 16 percent by eight. Keep some training going through busy weeks, since the steepest loss comes in the first three weeks of doing nothing. More in how fast do you lose VO2 max?
What your result means, and what to do next
- Low or below average. Most of the health gap sits in the first step up, so this is where training pays the most.
- Above average or high. Hold it as the years pass. Holding steady after 40 already counts as climbing.
- The next group up is a target for one training block, but people respond very differently, from almost nothing to a lot.
- Make sure the number is real. A watch can be several points off. Get your true VO2 max
- Start the two layers. Cardio most days at a pace where you can still talk, and one or two hard sessions a week. How to raise it
- Retest the same way in 8 to 12 weeks. Same test, same route or same watch. Believe a change of more than 2 to 4 points.
8 sources
- Bacon AP and others, VO2max trainability and high intensity interval training in humans: a meta-analysis, PLOS ONE, 2013pmc.ncbi.nlm.nih.gov
- Helgerud J and others, Aerobic high-intensity intervals improve VO2max more than moderate training, Medicine and Science in Sports and Exercise, 2007europepmc.org
- Milanović Z, Sporiš G and Weston M, Effectiveness of high-intensity interval training (HIT) and continuous endurance training for VO2max improvements: a systematic review and meta-analysis of controlled trials, Sports Medicine, 2015europepmc.org
- Bouchard C and others, Familial aggregation of VO2max response to exercise training: results from the HERITAGE Family Study, Journal of Applied Physiology, 1999europepmc.org
- McGuire DK and others, A 30-year follow-up of the Dallas Bedrest and Training Study: II. Effect of age on cardiovascular adaptation to exercise training, Circulation, 2001europepmc.org
- Molina-Garcia P and others, Validity of estimating the maximal oxygen consumption by consumer wearables: a systematic review with meta-analysis and expert statement of the INTERLIVE network, Sports Medicine, 2022pmc.ncbi.nlm.nih.gov
- Coyle EF and others, Time course of loss of adaptations after stopping prolonged intense endurance training, Journal of Applied Physiology, 1984europepmc.org
- Kaminsky LA and others, Updated reference standards for cardiorespiratory fitness measured with cardiopulmonary exercise testing (FRIEND), Mayo Clinic Proceedings, 2022mayoclinicproceedings.org
