Genetic and environmental influences on VO2max heritability: twin studies review

The researchers reviewed studies comparing twins to estimate what shapes VO2max, the maximum amount of oxygen the body can use during hard exercise. Identical twins share nearly all their genes, while non-identical twins share about half, so differences between them can suggest genetic effects. The studies found that genes play a meaningful role in VO2max, but exercise habits and other environmental factors also matter. The size of the genetic contribution varied widely between studies and people.

What this means for you: Your genes may affect how easily your fitness improves, but they do not set a fixed limit. Regular exercise can still improve VO2max, and this review does not identify a specific product or training plan as best.