Maximal oxygen uptake, lung volume and ventilatory response to carbon dioxide and hypoxia in a pair of identical twin athletes.

1. Maximal oxygen uptake (VO2 max), lung volumes, and ventilatory responses to carbon dioxide and hypoxia have been measured in identical twin athletes, who were trained to a similar high degree. 2. The results confirm previous findings for VO2 max. and lung volumes in identical twins, and are in keeping with the suggestion that genetic factors play a major part in determining the ventilatory response to carbon dioxide and hypoxia.