Cardiorespiratory function in competitive endurance runners aged 12-16 years compared with ordinary boys.

Thirty-four male elite endurance runners aged 12-16 years and 56 ordinary boys of the same age were studied in cross-sectional age groups. At the age of 12-14 years, there were only a few differences between the runners and the controls: the runners weighted less, were leaner and had higher VO2 max/kg body weight. The runners' good competitive performance could not be explained by a superior aerobic power at that age. In the age group of 16-year-olds, additional major differences were found: significantly higher VO2 max (4.05 1/min, 66 ml/min/kg), W170 (214 W, 3.5 W/kg), vital capacity (5.31 l), maximal expiratory volume (153 1/min), lower resting heart rate (62 beats/min) and larger heart volume (792 ml and 453 ml/m2 BSA) in the runners. In this respect our runners resembled adult endurance athletes. No differences could be observed in any age group as to height, hemoglobin concentration, blood pressure and maximal heart rate. The differences at the age of 16 years are either training effects or due to a selection of certain "endurance runner types".