The Nation : Genes, Athletics Linked

Heart muscles adapt to endurance training in ways that depend at least partly on a person’s genes, according to researchers who studied 10 sets of identical twins in a rigorous 20-week exercise regimen. Researchers found also that 20 sedentary persons who had never trained before and who underwent the same regimen showed significant increases in the size of their heart muscles and their capacity to exercise. The study, published in the Journal of the American Medical Assn., is the first of its type to indicate that athletes with the capacity to be champions are determined by heredity and not merely by training.