Cardiovascular responses to treadmill and cycle ergometer exercise in children and adults

Turley, Kenneth R., and Jack H. Wilmore. Cardiovascularresponses to treadmill and cycle ergometer exercise in children andadults. J. Appl. Physiol. 83(3):948-957, 1997.This study was conducted to determine whethersubmaximal cardiovascular responses at a given rate of work aredifferent in children and adults, and, if different, what mechanismsare involved and whether the differences are exercise-modalitydependent. A total of 24 children, 7 to 9 yr old, and 24 adults, 18 to26 yr old (12 males and 12 females in each group), participated in bothsubmaximal and maximal exercise tests on both the treadmill and cycleergometer. With the use of regression analysis, it was determined thatcardiac output () was significantly lower(P  0.05) at a givenO₂ consumption level(O₂, l/min) in boys vs. menand in girls vs. women on both the treadmill and cycle ergometer. Thelower in the children was compensated for by asignificantly higher (P  0.05)arterial-mixed venous O₂difference to achieve the same or similarO₂. Furthermore, heart rateand total peripheral resistance were higher and stroke volume was lowerin the children vs. in the adult groups on both exercise modalities.Stroke volume at a given rate of work was closely related to leftventricular mass, with correlation coefficients ranging fromr = 0.89-0.92 andr = 0.88-0.93 in the males and females, respectively. It was concluded that submaximal cardiovascular responses are different in children and adults and that these differences are related to smaller hearts and a smaller absolute amountof muscle doing a given rate of work in the children. The differenceswere not exercise-modality dependent.