title: Maturation of ventilatory responses to 1-minute exercise.
abstract: To test the hypothesis that ventilatory responses to exercise mature during growth in healthy children, we examined CO2 production (VCO2) and minute ventilation (VE) before, during, and for 10 min after 1-min bursts of cycle ergometry exercise. Ten children (range: 7-11 y old) and 13 adults (26-42 y old) exercised at work rates corresponding to 50 and 80% of the anaerobic or lactate threshold, 50% of the difference between anaerobic threshold and maximum O2 consumption, 100% of maximum O2 consumption, and 125% of maximum O2 consumption (125% max). Gas exchange was measured breath by breath. Children recovered faster from high-intensity (above anaerobic threshold) exercise as judged by the time constant of single exponential curve-fits to postexercise VCO2 [55 +/- 10 s (1 SD) at 125%. max in children compared with 92 +/- 17 s at 125% max in adults; p less than 0.001] and VE (58 +/- 10 s at 125% max in children compared with 125 +/- 37 s in adults, p less than 0.001). Although we found no significant difference between VCO2 and VE recovery times in children, VE was significantly slower than VCO2 in adults for high-intensity exercise. Moreover, recovery times in adults increased with work intensity but were independent of them in children. Whereas the CO2 costs [calculated as total CO2 produced above baseline per unit work done (mL.J-1)] increased with work intensity in adults, no similar significant relationship was observed in children.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Pediatrics, Harbor-UCLA Medical Center, Torrance 90509.
authors.forename: Y
authors.initials: Y
authors.lastname: Armon
authors.forename: D M
authors.initials: DM
authors.lastname: Cooper
authors.forename: S
authors.initials: S
authors.lastname: Zanconato
mesh_terms: D000328:Adult; D000367:Age Factors; D002245:Carbon Dioxide; D002648:Child; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012119:Respiration / Q000502:physiology*; D012143:Respiratory Physiological Phenomena; D012137:Respiratory System / Q000254:growth & development
chemical_list: D002245:Carbon Dioxide