VO2 max trainability varies widely
VO2max responds to training but the size of the response varies substantially between individuals and is constrained by genetics, baseline fitness, and training history.
In plain English
New and recreational runners often raise their VO2 max (the most oxygen the body can use) by 5 to 20 percent. Well-trained runners gain less, usually 1 to 5 percent. A few people barely respond, even when they train hard and stay consistent.
Why it works
Improvements come from increased stroke volume, higher blood volume, and more peripheral oxidative capacity. The ceiling and rate of adaptation are genetically influenced.
What it means in practice
Avoid promising fixed VO2max gains. Frame training as setting up the conditions for adaptation rather than guaranteeing a specific improvement. When a runner is not seeing expected progress, do not assume they are doing something wrong; some variability is biological.
The evidence
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The concept of fixed inter-individual differences in trainability has been overstated. Studies using more intense or progressive training (interval training, longer programs) show VO2max increases in essentially all participants, contradicting earlier reports of a substantial 'non-responder' fraction at modest training doses. The authors argue that what looks like genetic non-responsiveness is largely a training-stimulus issue: under-dosed protocols produce small mean responses with high apparent variability, but adequate stimulus produces near-universal improvement. They propose new twin-study designs to separate true genetic limits from training-stimulus inadequacy.
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Distance running performance can be modeled as the product of three physiological factors: VO2max sets the upper ceiling on aerobic energy availability; lactate threshold determines the fraction of VO2max sustainable for the race duration; running economy determines the oxygen cost of producing a given speed. Combined optimally, these factors predicted a theoretical marathon time of approximately 1:57:58, which was approximately 8 minutes faster than the world record at the time of publication. The model framed the research agenda for the next several decades of endurance physiology and informed the Nike Breaking2 and INEOS 1:59 projects.
Why we call confidence high
Joyner's 2018 review consolidates decades of training studies showing that VO2max is trainable but with a wide range of individual responses, including a notable fraction of low responders. The HERITAGE family studies showed substantial genetic component to trainability.
Where it applies
Adult runners across training levels. Beginners and detrained adults see the largest gains.
Does not apply to: children, where growth-related changes confound training adaptation; elite athletes near their physiological ceiling.
Last reviewed 2026-05-01. See how we score.