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

Abstract

This study was conducted to determine whether submaximal cardiovascular responses at a given rate of work are different in children and adults, and, if different, what mechanisms are involved and whether the differences are exercise-modality dependent. A total of 24 children, 7 to 9 yr old, and 24 adults, 18 to 26 yr old (12 males and 12 females in each group), participated in both submaximal and maximal exercise tests on both the treadmill and cycle ergometer. With the use of regression analysis, it was determined that cardiac output (Q) was significantly lower (P </= 0.05) at a given O2 consumption level (VO2, l/min) in boys vs. men and in girls vs. women on both the treadmill and cycle ergometer. The lower Q in the children was compensated for by a significantly higher (P </= 0.05) arterial-mixed venous O2 difference to achieve the same or similar VO2. Furthermore, heart rate and total peripheral resistance were higher and stroke volume was lower in the children vs. in the adult groups on both exercise modalities. Stroke volume at a given rate of work was closely related to left ventricular mass, with correlation coefficients ranging from r = 0.89-0.92 and r = 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 amount of muscle doing a given rate of work in the children. The differences were not exercise-modality dependent.

Valores de consumo máximo de oxigênio determinados pelo teste cardiopulmonar em adolescentes: uma proposta de classificação

“…15 This is because, instead of a reduced capacity to increase maximum cardiac output, in conjunction with lower systolic volume, adolescents exhibit increased maximum chronotropic capacity and greater efficiency in the use of the oxidative, rather than the glycolytic, ATP resynthesis. 12,22 Nevertheless, the capacity of these youngest subjects to perform work is greatly reduced as due to structural limitations to the cardiorespiratory system resulting from the smaller size of these organs and from biochemical limitations to anaerobic ATP production. 9,22,23 Another significant difference between adults and adolescents is the difficulty involved in achieving a VO 2 plateau, in order to identify maximum aerobic fitness.…”

“…12,22 Nevertheless, the capacity of these youngest subjects to perform work is greatly reduced as due to structural limitations to the cardiorespiratory system resulting from the smaller size of these organs and from biochemical limitations to anaerobic ATP production. 9,22,23 Another significant difference between adults and adolescents is the difficulty involved in achieving a VO 2 plateau, in order to identify maximum aerobic fitness. 9,20,24 Studies 23,25,26 suggest that peak VO 2 is a good indicator of aerobic fitness in children, even when a VO 2 plateau is not attained.…”

Cardiopulmonary exercise testing in congenital heart disease: (contra)indications and interpretation

“…1 For normal children, RER values at VO 2peak reported during cycle ergometry generally range from 1.0 to 1.10. 48 …”

Comparação das variáveis cardiorrespiratórias de adolescentes obesos e não obesos em esteira e bicicleta ergométrica

“…Alguns trabalhos relataram valores similares na esteira e bicicleta ergométrica (6,20) ; contudo, outros encontraram maiores valores na esteira (21) . Neste estudo, quando comparada a FC max obtida nos ergômetros, os testes na esteira ergométrica apresentaram maiores valores do que na bicicleta.…”