Ventilatory control during exercise in normal children.
We investigated the relation between age and respiratory control during exercise in 80 children aged 6.4-17.6 y (42 male, age, 11.6 +/- 3.3 y; body weight, 41.3 +/- 14.7 kg; and 38 female, age, 12.6 +/- 2.7 y; body weight, 42.5 +/- 9.3 kg). Exercise tests were performed on a treadmill after a standard symptom-limited Bruce protocol. Data were analyzed separately for boys and girls. At rest and at peak exercise, the ratio of minute ventilation to carbon dioxide production (VE/VCO2), the ratio of effective alveolar ventilation to carbon dioxide production (VA/VCO2), the ratio of pulmonary dead space to tidal volume (Vd/Vt), and arterial PCO2 (PaCO2) were not correlated with age. At the exercise intensity of ventilatory anaerobic threshold, the PaCO2 increased, and the VA/VCO2 decreased, significantly with age, whereas the Vd/Vt was not related to age. Linear regression analysis demonstrated that the slope of the relationship between VE and VCO2 (deltaVE/deltaVCO2) and the slope of the relationship between VA and VCO2 (deltaVA/deltaVCO2) decreased with age. There were no gender differences in the regression slopes and the intercepts of the relationships. Results show that younger children breathe more during exercise to eliminate a given amount of CO2 to keep PaCO2 set point slightly but significantly lower than older children. This age dependence must be considered in investigating ventilatory control during exercise in children.
Nagano
Y
Y
Department of Pediatrics, Nagoya University School of Medicine, Japan.
Baba
R
R
Kuraishi
K
K
Yasuda
T
T
Ikoma
M
M
Nishibata
K
K
Yokota
M
M
Nagashima
M
M
D000293:Adolescent; D000367:Age Factors; D002245:Carbon Dioxide / Q000097:blood; D002648:Child; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D010313:Partial Pressure; D005082:Physical Exertion / Q000502:physiology*; D011650:Pulmonary Alveoli / Q000502:physiology; D012016:Reference Values; D012044:Regression Analysis; D012119:Respiration / Q000502:physiology*; D012727:Sex Characteristics; D013990:Tidal Volume; D014692:Ventilation-Perfusion Ratio
D002245:Carbon Dioxide