title: Genetic and environmental determinants of the cardio-respiratory response to submaximal exercise--a six-year follow-up study of twins.
abstract: The fat-free mass and the ventilatory and cardiac frequency responses to submaximal exercise have been assessed longitudinally over six years in a total of 65 identical and non-identical boy and girl twin pairs. Exercise ventilation at rates of work below the anaerobic threshold was independent of the genetic and environmental factors which were investigated. The anaerobic threshold increased with age. The fat-free mass and the exercise cardiac frequency were subject to both genetic and environmental control with the genetic component predominating initially. The subsequent environmental component was larger for non-identical than for identical twin pairs and for boys than for girls. It is concluded that in identical twin boys by the time they reach adolescence the performance during submaximal exercise has a material environmental component. There appears to be interaction between the genetic and environmental components.
mesh_terms: D000293:Adolescent; D002648:Child; D004777:Environment; D005080:Exercise Test; D005260:Female; D005826:Genetics, Medical; D006321:Heart / Q000502:physiology*; D006801:Humans; D008297:Male; D005082:Physical Exertion; D011247:Pregnancy; D012143:Respiratory Physiological Phenomena; D014427:Twins; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic