LAUSR

Introduction: Tidal expiratory flow limitation (EFLT) occurs when the tidal breath reaches its maximal capacity to generate flow despite increased expiratory effort. It has been suggested there are gender differences; females tend to develop EFLT due to lower markers of ventilatory capacity, and the primary determinants of EFLT in males relate to higher oxygen demand. Aim/hypothesis: This study aimed to determine the prevalence and predictors of EFLT during peak exercise in healthy subjects aged 10-24 years. We hypothesised that the prevalence and predictors of EFLT would not differ between males and females. Method: Healthy, physically active subjects (n=122, 69M:53F) with normal spirometry and gas exchange completed a maximal cardiopulmonary exercise test. The presence and degree of EFLT during peak exercise was determined by the vector-based analysis technique described by Welch et al (2021). Student’s T-test compared continuous variables and predictors of EFLT were determined by two-way ANOVA for sex and the presence of EFLT. Results: EFLT was present in 70% of subjects, with no difference in the prevalence between males and females (74 vs. 66%). The degree of EFLT was significantly greater in the males compared to females (40 vs. 30% of tidal volume, p<0.05). Subjects demonstrating EFLT had relatively lower forced expired volume in the first second (FEV1), FEV1/forced vital capacity ratio, and mid expiratory flows. During peak exercise, male and female subjects demonstrating EFLT had higher relative peak oxygen consumption, ventilatory equivalents, breathing frequency, and minute ventilation relative to body weight. Conclusion: This study showed no gender difference in the prevalence of EFLT in healthy, physically active subjects. For both genders, lower markers of ventilatory capacity and higher markers of oxygen demand were predictors of EFLT. This research was supported by an award from The Green Lane Research and Education Fund Board. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.