Exercise-Induced Bronchoconstriction in Children with Controlled Asthma Without Prominent Exercise-Related Symptoms: Prevalence and Associated Factors

Background/Objectives: Exercise-induced bronchoconstriction (EIB) may persist despite apparently adequate asthma control and may remain unrecognized in children without prominent exercise-related symptoms. This study aimed to determine the prevalence of objectively confirmed EIB in children with controlled asthma who did not report prominent exercise-related respiratory symptoms and to identify factors associated with EIB. Methods: This cross-sectional study included 67 children with controlled asthma who underwent standardized exercise challenge testing with serial spirometry. Demographic, environmental, allergic, laboratory, aeroallergen sensitization, and baseline pulmonary function characteristics were evaluated. Children were classified as EIB-positive or EIB-negative according to their post-exercise FEV1 response. Factors associated with EIB were assessed using univariate analyses and multivariable logistic regression. Results: EIB was identified in 24 of 67 children (35.8%). Baseline pulmonary function was generally preserved and did not differ significantly between EIB-positive and EIB-negative children. A history of atopic eczema was more frequent in the EIB-positive group (37.5% vs. 14.0%; p = 0.035). Allergic rhinitis, food allergy, total IgE, eosinophil percentage, and aeroallergen sensitization were not significantly associated with EIB. In multivariable logistic regression, a history of atopic eczema remained associated with EIB (adjusted odds ratio, 3.95; 95% CI, 1.08–14.41; p = 0.038), although the wide confidence interval indicates substantial uncertainty in the effect estimate. Conclusions: EIB was objectively detected in more than one-third of children with controlled asthma without prominent exercise-related symptoms despite preserved baseline pulmonary function. A history of atopic eczema may help identify children with persistent susceptibility to exercise-induced airway narrowing who might otherwise remain unrecognized.