WILBER, R. L., K. W. RUNDELL, L. SZMEDRA, D. M. JENKINSON, J. IM, and S. D. DRAKE. Incidence of exercise-induced bronchospasm in Olympic winter sport athletes. Med. Sci. Sports Exerc., Vol. 32, No. 4, pp. 732–737, 2000.
Purpose: The purpose of this project was to determine the incidence of exercise-induced bronchospasm (EIB) among U.S. Olympic winter sport athletes.
Methods: Subjects included female and male members of the 1998 U.S. Winter Olympic Team from the following sports: biathlon, cross-country ski, figure skating, ice hockey, Nordic combined, long-track speedskating, and short-track speedskating. Assessment of EIB was conducted in conjunction with an “actual competition” (Olympic Trials, World Team Trials, World Cup Event, U.S. National Championships) or a “simulated competition” (time trial, game), which served as the exercise challenge. Standard spirometry tests were performed preexercise and at 5, 10, and 15 min postexercise. An athlete was considered EIB-positive based on a postexercise decrement in FEV1 ≥ 10%.
Results: For the seven sports evaluated on the 1998 U.S. Winter Olympic Team, the overall incidence of EIB across all sports and genders was 23%. The highest incidence of EIB was found in cross-country skiers, where 50% of the athletes (female = 57%; male = 43%) were diagnosed with EIB. Across the seven sports evaluated, the prevalence of EIB among the female and male athletes was 26% and 18%, respectively. Among those individuals found to be EIB-positive were athletes who won a team gold medal, one individual silver medal, and one individual bronze medal at the Nagano Winter Olympics.
Conclusions: These data suggest that: 1) EIB is prevalent in several Olympic winter sports and affects nearly one of every four elite winter sport athletes; 2) the winter sport with the highest incidence of EIB is cross-country skiing; 3) in general, EIB is more prevalent in female versus male elite winter sport athletes; and 4) athletes may compete successfully at the international level despite having EIB.
It is well established that a cold and dry ambient environment is an important factor contributing to the severity of exercise-induced bronchospasm (EIB) (2). Increased bronchial responsiveness resulting from the performance of exercise in cold and dry environmental conditions has been associated with two potential pathophysiological mechanisms (13,15). The first of these mechanisms is referred to as the hyperosmolarity theory. This theory contends that the exercise-induced hyperventilation of cold dry air leads to a loss of heat and water from the epithelium of the bronchial mucosa, a physiological response that is necessary to warm and humidify the inhaled air. The loss of heat and water from the bronchial mucosa results in an increase in the tissue’s osmolarity, which in turn triggers the release of histamine and other mediators to induce bronchoconstriction. The second proposed mechanism, the thermal expenditure theory, proposes that rapid rewarming of the airways after exercise causes bronchoconstriction. Specifically, it is believed that during intense exercise in a cold and dry environment, heat is lost to the exhaled air from the bronchiolar blood vessels of the pulmonary vascular bed. After exercise, these bronchiolar blood vessels are rewarmed, which results in vasodilation and hyperemia, thereby causing bronchoconstriction.
Despite the fact that a cold and dry ambient environment is a well known exacerbant of exercise-induced bronchospasm, there are minimal data on the incidence of EIB in winter sport athletes. Data are particularly scarce for winter sport athletes who are competitive at the World Championship and/or Olympic level. Larsson et al. (8) used a methacholine challenge protocol to assess the incidence of asthma in elite Swedish female and male cross-country skiers (N = 42) and age- and gender-matched control subjects (N = 29). Asthma was defined as “bronchial hyperresponsiveness” (quantified as a PC20 methacholine concentration below the 10th percentile of control values) plus two symptoms identified from a written survey (cough, abnormal shortness of breath, chest tightness, and wheezing induced by asthma trigger factors, such as exercise and/or cold air). Asthma, as defined by the study criteria, was significantly more prevalent in the cross-country skiers (33%) versus the control subjects (3%). In addition, 55% of the athletes had asthma as defined by the study criteria or as previously diagnosed by a physician. There was no significant difference in bronchial responsiveness between the winter and summer seasons in either the skiers or controls (8). Provost-Craig et al. (10) reported that within a group of 100 competitive figure skaters (including some Olympic caliber athletes), 30% of the athletes were EIB-positive based on a postexercise decrement in FEV1 ≥ 10%. Heir and Oseid (5) used a questionnaire to determine the prevalence of asthma and/or EIB among “high level” female and male Norwegian cross-country skiers (N = 153) and age-, gender-, and environmentally-matched controls (N = 306). The prevalence of asthma “as diagnosed by a physician” was significantly higher in the cross-country skiers (14%) versus the controls (5%). In addition, exercise-induced respiratory symptoms (chest tightness, shortness of breath, cough, wheezing, and sputum production) were much more frequent among the cross-country skiers; at least one exercise-induced respiratory symptom was reported by 86% of the athletes compared with 35% of the control subjects (5). Survey data reported recently by Weiler and Hunt (17) indicated that 17% of the athletes on the 1998 U.S. Winter Olympic Team had a history of EIB. Within that group, 12% had a known diagnosis of asthma and had taken medications, 3% had a diagnosis but were not taking medications, and 2% had never been diagnosed but took asthma medications (17).
Collectively, limited data on the incidence of exercise-induced bronchospasm among elite winter sport athletes suggests that asthma and/or EIB are more prevalent in elite athletes versus age-, gender-, and environmentally-matched controls. However, the few studies that have assessed the incidence of EIB in elite winter sport athletes have relied on survey data or have evaluated EIB in a limited number of winter sports (cross-country skiing, figure skating). Accordingly, the purpose of this project was to evaluate the prevalence of EIB among Olympic team athletes from several winter sports using pre- and post-exercise spirometry. A unique aspect of this study was the fact that EIB screening was conducted on Olympic athletes in the field in conjunction with an “actual competition” (Olympic Trials, World Team Trials, World Cup Event, U.S. National Championships) or a “simulated competition” (time trial, game). We believed that evaluation of EIB in the field using an actual or simulated competition as the exercise challenge would provide two distinct advantages over testing in the clinical environment: 1) athletes would produce a sustained competitive effort, as opposed to exercising for 6–8 min at 85–90% HRmax per a standard clinical protocol; and 2) athletes would be evaluated in the ambient cold environment in which they typically train and compete. Thus, by using a protocol that allowed for the evaluation of EIB during highly competitive, sport-specific situations in a cold ambient environment, we believed that a more valid quantification of the incidence of EIB among Olympic winter sport athletes would result.