2017 Volume 8 Issue 1 Pages 1-8
Objectives: Exercise-induced bronchoconstriction (EIB) is a transient acute airway narrowing that occurs as a result of exercise. Approximately 80% of individuals with asthma experience exercise-related symptoms (ERS). The prevalence of EIB in the general population without a known asthma diagnosis has been estimated to be approximately 5%–20%, but there is no consensus on this. There have been previous studies on asthma patients, infants and athletes, but few studies have investigated general students, particularly in Japan. The purpose of our study was to investigate the prevalence of EIB with screening questionnaires and laboratory exercise challenge tests in Japanese medical students.
Methods: This study included 233 potential participants. All participants completed an EIB screening questionnaire. The exercise protocol for the bicycle ergometer started at 25 W, and the participant remained in motion for 5 min in a multi-step load protocol that increased by 25 W per min. Spirometry was performed before and after all exercise challenge tests. The criterion for a positive test was a ≥10% decrease in forced expiratory volume in 1 s (FEV1) from the baseline measurement.
Results: Twenty-six of 217 students (12.0%) had a self-reported a history of ERS. However, only six students (2.8%) were EIB-positive on an objective test. Moreover, all six students had no history of asthma, ERS or EIB diagnosis.
Conclusions: Our data revealed EIB-positive participants in a generally healthy population. It is important that EIB diagnoses should not be made using only symptoms, a history of asthma, allergies or the baseline measurement of lung function. Objective tests should be used for the accurate diagnosis of EIB.
