Refractory period following induced asthma: Contributions of exercise and isocapnic hyperventilation

Issaschar Ben-Dov, Ilan Gur, Ephraim Bar-Yishay, Simon Godfrey

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


To compare the refractory period that follows exercise and isocapnic hyperventilation, 10 asthmatic children performed two pairs of challenge tests in random order at least six hours apart. In pair A a hyperventilation challenge was followed by an exercise challenge and in pair B the order was reversed. Both pairs of tests were done while the children were breathing cold dry air. Tests were matched in terms of work load, ventilation, and end tidal carbon dioxide tension (Pco2). The mean percentage fall in FEV1, (Δ FEV1) after the first challenge (hyperventilation) of pair A and the first challenge (exercise) of pair B were the same (30% (SEM 2%)) and 30% (4%) respectively). The mean Δ FEV1, of the exercise test following hyperventilation in pair A and of hyperventilation following exercise in pair B was 22% (4%) and 18% (4%) respectively. Both these latter results were significantly lower than the respective Δ FEV1, when the challenge was the first test of the pair. Although the mean refractoriness index (reduction in induced asthma in the second test of each pair compared with the first test) was greater when exercise was the first challenge, the difference was not significant.

Original languageEnglish
Pages (from-to)849-853
Number of pages5
Issue number11
StatePublished - 1 Jan 1983
Externally publishedYes

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine


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