Abstract

The aim of this study was to determine whether asthmatic children have maximal aerobic power and if ventilatory threshold is lowered during maximal exercise. Thus 11 children with asthma and 11 normal children (aged 11-13 years) were studied during an incremental load exercise with a cycle ergometer (30 W/min). For each work load, we measured gas exchange and breathing pattern. In addition, this protocol allowed us to determine the ventilatory threshold. The asthmatic children had lower values of VO2max expressed in ml/kg/min (37.26 +/- 3.95 versus 45.22 +/- 6.55) and ml/kg LBM/min (43.01 +/- 4.22 versus 50.69 +/- 7.26) in spite of the fact they could attain the same maximal power. They overtook their VO2max before their maximal heart rate. The ventilatory threshold was the same in the two groups. At maximum level of exercise, the children with asthma had lower values of VE, f and an increase of Ti. Thus the ratio VT/Ti was lowered. In addition. we observed a lower VCO2 for identical values of FCCO2. At the ventilatory threshold the Ti increase was the only difference observed. In conclusion, this study shows that asthmatic children have an aerobic limitation influenced by the previous state of the airways only during the final phase of exercise, but that this is partly compensated for by a significant anaerobic participation. Thus the asthmatic child is able to attain comparable maximal power as the normal subject. The question now is to determine if this limitation can be reversed or not by physical training. Verf.-Referat