Key takeaways
In the HERITAGE study of 481 adults, about 47% of the variation in VO2max response was linked to family resemblance
On one 20-week plan, VO2max rose 15 to 20% on average, but gains ranged from almost nothing to over 1 L/min
In a 2017 study, every non-responder improved after adding two extra sessions a week
Two friends start the same running plan. After five months one has improved her VO2max by 20%, the other by 3%. Bad luck? Bad training? Research has a fairly clear answer: both genes and dose.
The HERITAGE Family Study
In the 1990s, researchers trained 481 sedentary adults from 98 families on supervised stationary bikes, three times a week for 20 weeks, with intensity increasing over time. Everyone did the same programme.
- On average, VO2max rose substantially, by around 15–20%.
- But individual changes ranged from almost nothing to more than a litre per minute of extra oxygen uptake.
- Responses clustered in families: about half (≈47%) of the variation in response was attributed to family resemblance — an estimate of heritability.
Later work identified many gene variants each contributing a small amount; there is no single "endurance gene".
Non-responders respond to more
In 2017, Montero and Lundby trained 78 healthy adults for six weeks with one to five sessions per week. In the lowest-dose groups, many people showed no meaningful VO2max gain. Those "non-responders" then completed another six weeks with two extra sessions per week — and every one of them improved.
The lesson: low response to a fixed programme is common; true non-response to enough training is rare.
Other factors you control
- Starting point: the less fit you are, the more you gain. Trained athletes improve slowly.
- Intensity: intervals near maximum (like the 4×4) tend to raise VO2max more than moderate continuous training alone, in the same time.
- Consistency: weeks and months of training matter more than any single session.
- Recovery: sleep, food and stress decide whether you adapt. See resting heart rate, HRV and recovery.
- Body weight: changes relative VO2max directly. See VO2max and body weight.
What to do if you're stuck
- Check the trend over 8–12 weeks, not 2.
- Add volume or a session per week before blaming genes.
- Make the hard days hard and the easy days easy (80/20).
- Remember VO2max isn't everything: threshold and economy can keep improving after VO2max plateaus. See what limits VO2max.
Frequently asked questions
Why is my VO2max not improving?
Low response to a fixed programme is common, and genes explain part of it. Check your trend over 8 to 12 weeks, then add volume or a session per week before blaming genes; in one study every non-responder improved with two extra weekly sessions.
Is VO2max genetic?
Partly. In the HERITAGE Family Study, about half of the variation in how much people improved was attributed to family resemblance, but many gene variants each contribute a small amount and there is no single endurance gene.
Are there non-responders to exercise?
Low response to a fixed programme is common, but true non-response to enough training is rare. When non-responders added two sessions a week for six weeks, every one of them improved.
Sources
- Bouchard C, et al. Familial aggregation of VO2max response to exercise training: results from the HERITAGE Family Study. J Appl Physiol, 1999.
- Montero D, Lundby C. Refuting the myth of non-response to exercise training: "non-responders" do respond to higher dose of training. J Physiol, 2017.