Ventilatory response of prepubertal boys and adults to carbon dioxide at rest and during exercise

Abstract

The aim of this study was to determine whether the greater ventilation in children at rest and during exercise is related to a greater CO2 ventilatory response. The CO2 ventilatory response was measured in nine prepubertal boys [10.3 years (SD 0.1)] and in 10 adults [24.9 years (SD 0.8)] at rest and during moderate exercise (VCO2 = 20 ml.kg-1.min-1) using the CO2-rebreathing method. Three criteria were measured in all subjects to assess the ventilatory response to CO2: the CO2 sensitivity threshold (Th), which was defined as the value of end tidal PCO2 (PETCO2) where the ventilation increased above its steady-state level; the reactivity slope expressed per unit of body mass (SBM), which was the slope of the linear relation between minute ventilation (VE) and PETCO2 above Th; and the slope of the relationship between the quotient of tidal volume (VT) and inspiration time (tI) and PETCO2 (VT.tI-1.PETCO2(-1)) values above Th. The VE, VT, breathing frequency (fR), oxygen uptake (VO2), and CO2 production (VCO2) were also measured before the CO2-rebreathing test. The following results were obtained. First, children had greater ventilation per unit body weight than adults at rest (P < 0.001) and during exercise (P < 0.01). Second, at rest, only VT.tI-1.PETCO2(-1) was greater in children than in adults (P < 0.001). Third, during exercise, children had a higher SBM (P < 0.02) and VT.tI-1.PETCO2(-1) (P < 0.001) while Th was lower (P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

High-intensity intermittent running training improves pulmonary function and alters exercise breathing pattern in children

“…The increase in _ V E resulted from an improvement in V T at peak exercise in TrG, while f b remained constant. Such adaptation in V T could result in deeper ventilation at peak exercise improving the renewal of alveolar air (Gratas-Delamarche et al 1993). Hence, the changes observed in breathing pattern at peak exercise allowed higher _ V E to respond to the increase in oxygen demand of the muscular tissues after training.…”

Effects of Gas Exchange on Acid‐Base Balance

“…(a) have a greater CO 2 production per unit body mass at rest (12,96) and during exercise (12) (b) have a lower arterial PCO 2 at rest (c) have a greater VE per kg body mass during exercise (96) (d) at rest, and during steady-state submaximal exercise, have a greater sensitivity of the respiratory centers to CO 2 (96) such that they have an exaggerated and more rapid (47) ventilatory response to exercise and to hypercapnia (increased VE/VCO 2 slope), and this responsiveness diminishes as age increases (47,96,214,235) (e) VCO 2 measured at the mouth increases substantially faster at the onset of exercise and returns to preexercise levels more quickly.…”

Exercise Oscillatory Ventilation in Patients With Fontan Physiology

“…This may be because of ongoing maturation of ventilatory regulation through adolescence. [31][32][33] Although the small number of events precludes definitive analysis, the available data suggest that the clinical relevance of EOV is unaffected by this unexpected association: EOV remained a significant predictor of the secondary outcome after adjustment for age.…”