EXERCISE PERFORMANCE IN CHILDREN WITH ASTHMA - IS IT DIFFERENT FROM THAT OF HEALTHY CONTROLS

Exercise tolerance and possible limitation in work capacity of asthmat ic children is still a matter of debate. The aim of this study was to compare ventilation and gas exchange response to exercise of asthmatic children viith that of healthy control. Exercise performance was eval uated in 80 children with mild-to-moderate asthma, aged 1-15 yrs, and in 80 healthy controls matched for age, height, weight and habitual le vel of physical activity, The children performed a maximal exercise te st on a treadmill, during which oxygen uptake (V'O-2), carbon dioxide output (V'CO2) and minute ventilation (V'E) were measured continuously , No premedication was given to the asthmatic children. Forced expirat ory volume in one second (FEV1) at rest was 93+/-11% of predicted in a sthmatic children and 95+/-9% pred in controls, After the run, the mea n fall in FEV1 was 13.9% (range 0-57%) and 1.6% (0-9%), respectively ( p<0.001). The two groups achieved similar maximum oxygen uptake (V'O-2 ,max) ((mean+/-SD) 40.3+/- 8.4 and 42.6+/-9.6 mL.min(-1).kg(-1) in ast hmatics and controls, respectively; Ns) and maximum minute ventilation output (V'E,max) (42.9+/-14.5 and 45.7+/-14.9 L.min(-1) respectively; NS). The kinetics of V'O-2, V'CO2 and V'E during the test revealed no differences between the two populations, Moreover, anaerobic threshol d and oxygen pulse were the same in the two groups. Asthmatics showed a ventilatory pattern with lower respiratory frequencies and greater t idal volumes during the run. These results suggest that asthmatic chil dren can achieve a level of exercise performance similar to that of he althy children, provided that they have a comparable level of habitual physical activity. The only difference found concerned the ventilator y pattern of the asthmatic children, which was characterized by a redu ced respiratory frequency and greater tidal volume at the same minute ventilation, The level of physical conditioning was found to be the ma in determinant of exercise tolerance for children with controlled asth ma.