Cardiac responses to progressive exercise in normal children: a synthesis

Abstract

The observations in these two studies also suggest 1) peripheral vasodilatation plays an important role in the early rise in stroke volume, 2) increasing heart rate acts to maintain a stable stroke volume and left ventricular diastolic dimension at high workloads, and 3) improvements in contractility serve to maintain stroke volume as the systolic ejection period shortens.

Measurement of exercise cardiac output by thoracic impedance in healthy children

“…More recently, Rowland et al (1997Rowland et al ( , 2000Rowland et al ( , 2001 affirmed this notion and corroborated findings previously described in adults, i.e. the initial rise in stroke volume generally terminated in a plateau at mild to moderate work intensity.…”

“…Cardiac output in healthy children during exercise has been measured by several different techniques: CO 2 rebreathing (Bar-Or et al 1971;Gadhoke and Jones 1971;Godfrey et al 1971;Miyamura and Honda 1973;Turley and Wilmore 1997); inert gas uptake (Seely et al 1974); Doppler echocardiography (Rowland et al 1997(Rowland et al , 2000; or invasive techniques (Cumming 1977;Eriksson et al 1971). Godfrey et al (1971) provided reference values for stroke volume during upright exercise in a relatively large sample of children spanning the testable pediatric age range using the indirect Fick [CO 2 ] method.…”

Effects of Exercise and Respiration on Blood Flow in Total Cavopulmonary Connection

“…2 This is in accordance with exercise studies in healthy children. 13 The respiratory pump had a pronounced effect on IVC flow at rest, with an inspiratory flow fraction of 1.9. Wexler et al 14 found that the velocity of IVC flow in healthy adult men increased in inspiration and that this respiratory pump effect was more pronounced with supine lower-leg exercise.…”

Comportamento das variáveis cardiovasculares, ventilatórias e metabólicas durante o exercício: diferenças entre crianças e adultos

“…The stroke volume, i.e., the quantity of blood ejected from the left ventricle during a systole, shows curvilinear kinetics in children during progressive physical exercise 3,9,17,18 , which is the same behavior seen in adults 19,20 . In an important study using Doppler and bidimensional echocardiography, Rowland et al 17 , attributed this curvilinear profile (plateau) to several mechanisms.…”

“…In an important study using Doppler and bidimensional echocardiography, Rowland et al 17 , attributed this curvilinear profile (plateau) to several mechanisms. These mechanisms are 1) peripheral vasodilatation playing an important role in the initial SV rise (smaller after load); 2) increased heart rate with greater workloads, maintaining a stable SV (plateau) and left ventricular diastolic dimension and 3) a greater responsiveness in contractility (inotropism) helping to maintain the SV relative to the greater work loads.…”