[Evolution of bronchial hyperreactivity during post-exercise asthma].

The occurrence of a late reaction following exercise induced asthma is questionable and its relationship with the non specific bronchial hyperreactivity is poorly known. In this study, nine patients (age 15-21 years) underwent an exercise challenge in order to (a) determine the incidence of immediate and late phase reaction and (b) analyse the modifications of non specific bronchial hyperreactivity. Study design was a follow; day-3: determination of bronchial responsiveness to metacholine; day 0: control day with FEV1 measurements every hour for 11 hours; day 1: exercise challenge followed by a careful observation of change in FEV1; day 2: new determination of bronchial responsiveness to metacholine. An immediate exercise induced bronchial obstruction was observed in 5 patients. A late phase reaction (6th hour) with a fall of FEV1 equal to or more than 20% has been demonstrated in two patients. For the former, the change in FEV1 did not differ from the value of the control day. For the second, the FEV1 changed spontaneously during the control day so that decreases of FEV1 during control and challenge days were parallel. Thus, no late phase reaction were observed (F = 0.46; ns). There was no modification of bronchial responsiveness to metacholine (pre-exercise: 1,784 +/- 1,970 [SD]; post-exercise 1,827 +/- 2,231 micrograms [SD]). The lack of true late phase reaction when the post-exercise change in FEV1 is compared to the one of a control day and the absence of modification of non specific bronchial hyperreactivity weaken the hypothesis of an inflammatory mechanism of exercise induced asthma.