Development of ventilatory responses to exercise in normal white children. A longitudinal study

Cross-sectional studies have indicated that the pattern of ventilatory responses to exercise evolves during the course of childhood. This 5-year study was designed to provide a longitudinal assessment of minute ventilation (VE), tidal volume (VT), and breathing frequency (fR) in 20 children (11 girls, nine boys) between the ages of 9 and 13 years. Subjects performed maximal and identical submaximal steady-state treadmill walking tests annually. No significant gender differences were observed in any of the three variables. At submaximal exercise, VT per kilogram remained stable, with a progressive fall in fR. As a result, submaximal VE per kilogram declined with age. A similar pattern was observed at maximal exercise, but the decrease in VE per kilogram was not statistically significant. Ventilatory equivalent for oxygen (VE/VO2) fell with age at submaximal exercise but declined only in the boys with maximal testing. VE/VO2 at maximal and submaximal exercise was greater in the girls at all ages. These findings support previous data derived from cross-sectional studies.