VO2 kinetics in asthmatic adolescents: A pilot study

In normal subjects, ventilatory rate and oxygen ventilation (VO2) increases during exercise from a resting state until maximal levels are attained, whereas it seems that in asthmatic patients this increase is higher. The aim of the study was to evaluate the kinetics of VO2 during a constant-load exercise in a group of 11-16 y.o. asthmatic patients. 17 adolescents with mild stable asthma were studied. On the first day a progressive workload was applied to calculate the presumable aerobic threshold, which was assumed to be 80% of the maximum load tolerated. On the next day the subjects were asked to pedal at this constant load and the VO2 kinetics were studied with a K4B2 and a Cosmed® cycloergometer. In 9 patients (53%) there was an increasing trend of VO2 consumption, whereas in 5 (29%) this trend was not highlighted. In 3 patients (18%) data was unobtainable because of incompletion of test or non-cooperation. In conclusion, it was not possible to outline a common pattern of VO2 consumption, but in more than a half of our patients the behaviour of VO2 consumption during constant load was similar to that of the normal population.