D1.52 - The Borg Fallacy in Olympic Athletes: Symptom Perception Fails to Identify Airway Hyperresponsiveness

Symptom-based assessment is commonly used in clinical practice and sports medicine to screen for airway disease. However, in elite athletes, constant exposure to high ventilatory demands and respiratory discomfort may modify symptom perception, potentially masking bronchoconstriction. We investigated the association between perceived dyspnea (Borg scale) and objective airway hyperresponsiveness (AHR) during methacholine challenge testing in Olympic athletes.

Portuguese Olympic athletes (n = 42; 66.7% male; median age 27 years, IQR 22.8–31.3) underwent standardized dose-based (dosimeter) methacholine bronchial challenge testing. Borg dyspnea scores (0–10) were recorded at baseline and after each methacholine dose step; peak Borg score and change from baseline (ΔBorg) were calculated. Airway hyperresponsiveness was defined as a ≥20% fall in FEV₁ at a cumulative methacholine dose (PD20), expressed in micromoles (µmol); 9 athletes (21.4%) met this criterion. Diagnostic performance of symptom-based screening was assessed using ROC analysis, with sensitivity, specificity and exact 95% confidence intervals calculated for a predefined ΔBorg threshold ≥2. Associations between ΔBorg and airway responsiveness were explored using Spearman correlation among athletes with measurable PD20.

Symptom-based screening showed limited ability to identify airway hyperresponsiveness. Using ΔBorg ≥2 as a screening threshold, sensitivity for detecting AHR was 55.6% and specificity 87.9%, resulting in nearly half of affected athletes remaining undetected. Overall discriminative performance was modest (AUC 0.684). Overall symptom perception during bronchial challenge was low, with a median peak Borg score of 1 (IQR 0–2) and a median ΔBorg of 0 (IQR 0–1). Among athletes with measurable PD20, the association between ΔBorg and airway responsiveness was weak and not significant. 

In Olympic athletes, symptom perception, as assessed by Borg scale, markedly underestimates objective airway hyperresponsiveness. Although transient symptoms may occur during bronchial challenge, symptom perception – whether assessed as peak intensity or change from baseline – does not reliably identify airway disease. These findings reinforce the need for objective testing of airway pathology in elite athletic populations.