Background: Exercise-induced bronchospasm (EIB) affects up to 35% of athletes and up to 90% of asthmatics. Asthma morbidity and mortality have increased over the past several decades among residents of Philadelphia, PA. It is possible that a simple free running test for EIB may serve as a tool to study the factors contributing to recent trends in asthma, and to screen for asthma in athletes in the urban setting.
Objectives: The purposes of this study were to (1) assess a free running test to screen for EIB, and (2) examine prevalence of and epidemiologic factors associated with EIB in high school athletes.
Design: Cross-sectional observational study on the incidence and risk factors for EIB. To validate our method and criteria for the diagnosis of EIB, a repeat test was performed on a portion of the athletes. In a randomized single-blinded fashion, 15 athletes who had demonstrated EIB initially received albuterol or placebo prior to a repeat exercise test.
Setting: Community high school athletic facilities.
Participants: We studied 238 male high school varsity football players.
Intervention: All athletes underwent an acquaintance session with a questionnaire, followed by a 1-mile outdoor run (6 to 8 mins).
Measurements: Peak expiratory flow (PEF) measurements were determined prior to and 5, 15, and 30 min after exercise. Heart rates (HRs) and dyspnea scores were measured. EIB was defined as a decrease of 15% in PEF at any time point after exercise. Associations of EIB with demographic factors were assessed by univariate and multivariate analyses.
Results: Two hundred thirty-eight athletes participated: 92 European-Americans (EA), 140 African-Americans (AA), 5 Hispanics, and 1 Native American. Mean age was 16 ± 1 years. Average HR postexercise was 156 ± 24 beats/min. Twenty-four (10%) reported a history of treated asthma. The prevalence of EIB among the remaining 214 athletes was 19 of 214 (9%). The rate of EIB among AA athletes was higher than among EA athletes: (17/126 [13%] AA vs 2/82 [2%] EA, p = 0.01). During the validation portion of the study, the placebo-treated group (n = 7) demonstrated a consistent drop in PEF after exercise on repeat testing, with a 16 ± 5% fall in PEF on initial testing and a 14 ± 13 drop with placebo. In contrast, the fall in airflow in the albuterol-treated athletes (n = 8) following exercise reversed with albuterol treatment, from a 15 ± 6% fall in PEF at initial testing to an increase in PEF of 6 ± 9% from baseline following albuterol administration. A history of wheezing (p < 0.001), residence in a poverty area (p < 0.0001), race (p = 0.01), remote history of asthma (p < 0.001), and absolute water content of the air on the day tested (p = 0.04) were significantly associated with EIB. By stepwise regression, EIB was most closely associated with a history of wheezing (p = 0.001) and poverty area residence (p = 0.003).
Conclusions: Our findings indicate a substantial rate of unrecognized EIB exists among urban varsity athletes, and suggest that active screening for EIB, especially for students residing in poverty areas, may be indicated to identify individuals at risk for EIB and asthma.