Pulmonary Function of Children With Asthma in Selected Indoor Sport Environments

Transcription

1 Pediatric Exercise Science, 1999, 11, O 1999 Human Kinetics Publishers, Inc. Pulmonary Function of Children With Asthma in Selected Indoor Sport Environments Thomas W. Pelham, Laurence E. Holt, and Michael A. Moss The objective of this study was to examine pre- and postexercise pulmonary function of males (13 children with asthma, 8 children without asthma) performing controlled exercise in 3 indoor sport environments: ice rink, gymnasium, and swimming pool. A positive test was defined as a 20% decrease in any of the forced expiratory values. Three children with asthma and 2 children without asthma had a greater than 20% decrease in FEV, and FEVT following activity in the rink. One child with asthma had a greater than a 20% decrease in FEV, following pool activity. In general, results showed children with asthma had a significant (p <.05) decrease in both FEV, and W T% 5 min following exercise in the ice rink. No similar decrease was found 5 min following gymnasium and pool activity of the same intensity. In general, children without asthma maintained normal pulmonary function in all 3 environments. Evidence from this study would seem to suggest that the environmental conditions of the indoor ice rink may potentiate bronchospasm in some children with asthma. Asthma has been recognized as a major disorder in childhood (6). It has been suggested that childhood asthma has resulted in more hospital admissions, more visits to hospital emergency rooms, and more school absences than any other chronic disease of childhood (6, 19). While the factors responsible for eliciting an asthmatic response may vary among children, research has suggested that particular modes of exercise and sporting activities have the potential to bring about adverse effects in some children with asthma (10). Moderate intensity, moderate duration activities have been shown to be more likely to elicit airway obstruction than high intensity, short duration activities (10). Swimming has been suggested to be a more favorable activity than running at equivalent durations and intensities (10). A bronchoconstriction/bronchospasm has been identified to be more likely in such outdoor sporting activities as cross-country skiing (13). This sport is usually performed in cold, dry air. Although some of the risk factors inherent in our indoor sport environments have been identified, the specific effects on the athletes and others in these environments need more study. T.W. Pelham is a physical therapist in private practice, Halifax, Nova Scotia, Canada. L.E. Holt is with the School of Health and Human Performance at Dalhousie University, Halifax, Nova Scotia, B3H 355, Canada. M.A. Moss is with the Department of Pathology at Dalhousie University.

2 Asthma and Indoor Environments This is surprising in light of the widespread utilization of indoor fitness and recreation facilities for organized youth sports. One indoor environment that may be culpable in regards to bronchoconstriction/bronchospasm in some children with asthma is the enclosed ice rink. Supporting evidence has come from two recent articles that reported significantly higher percentages of physician-diagnosed asthma among young male hockey players than males from the general population for those age groups (22, 24). These studies pointed to the additive effect of vigorous exercise plus the cold, dry, polluted air as contributing factors. With these facts in mind, the purpose of this study was to examine the pulmonary function of young males before and after exercise in three indoor sport environments: ice rink, gymnasium, and swimming pool. Subjects Methods A group of 13 young males (range in age: 7-12 years; range in height: m) with physician-diagnosed asthma and 8 male children without asthma (range in age: 7-12 years; range in height: m) were randomly selected from a large group of children attending a hockey skill camp. The physician-diagnosed condition was confirmed by the guardians of the subjects. Before any data were collected, the subjects and the guardians of these children gave informed consent, and were fully informed that the child's participation was voluntary and that the child could withdraw at any time. Subjects were from the Halifax-Dartmouth area. Fifteen subjects were originally selected as controls, as well as 15 for the experimental group; however, spirometry values of seven children without asthma and two experimental subjects were disqualified due to unsuitable data. Data was deemed unsuitable if the subject did not follow standard procedures for the lung function testing as outlined by Fems (9). All 13 children with asthma used antiasthma drugs regularly. Ten inhaled beta, agonists, two used a combination of beta, agonists and topical steroids, and one was prescribed a topical steroid (Beclomethasone). Salbutamol was the drug of choice, and most were administered by a metered dose inhaler. The frequency of use ranged from once to several times per day, with dosage varying. None of the children without asthma were prescribed a respiratory medication. Data Collection The study was administered during a hockey skill camp in Halifax, Nova Scotia. Forced expiratory volume (FEV,) and forced vital capacity (FVC) were recorded ----srr~&ablesgir~me~-re~n_modec2+~oil_the influence of age and physique on ventilatory function were controlled by expressing a3tvxe3ombjectsas a percentage of the preexercise score (10). The percentage forced expiratory flow was completed from each recording [FEVT% = (FJW, x 100)/FVC]. A positive test was defined as a 20% decrease in any of the forced expiratory values. A 20% decrease in any of the forced expiratory values was considered crucial based on the work by Hargreaves et al. (11) The Hargreaves et al. (11) method for histamine challenge testing used a 20% fall in FEV, as the termination

3 408 - Pelham, Holt, and Moss point for bronchial provocation. Bronchial provocation testing measures the degree of bronchial hyperreactivity, the important pathogenic mechanism of asthma. Sport Environments ice Rink. The ice surface was professional size. The spectator area was clean. Posttesting was adjacent to the ice surface, where air temperature near the ice surface was close to O C, and humidity and air circulation were low. Pretesting was administered in the fitness room that had a similar environmental profile as the gymnasium. The refrigeration system and ventilation system met all provincial and local codes and regulations. Gymnasium. The gymnasium was a large multipurpose room. The gymnasium floor was wet mopped, and the walls and the spectator facilities were clean. Air temperature was 22"C, and the humidity was moderate. Air flow met all provincial and local codes and regulations. Swimming Pool. The air temperature at the enclosed swimming pool was 25 C with moderate humidity. The indoor pool was 50 m in length and heated to a water temperature of 25 C. The scum line, pool duct, and strainers were clean. Less than 30 individuals were using the pool at any one time during the activity of the subjects. The circulation, filtration, and treatment of the water met all provincial and local codes and regulations. Air circulation met provincial and local regulations and codes. In all three environments, activities were highly structured and supervised by qualified sport and fitness professionals, who were fully aware of and sensitive to the cardiovascular responses to activity of the subjects. Drinking water was conveniently accessible in the three environments. The total activity time was 30 min. Five minutes were reserved for a warmup before each activity and 5 min, for a cool-down at the end of each activity in each environment. The warm-up and cool-down consisted of a series of slow and controlled flexibility exercises. The middle 20-min session was devoted to a mixture of submaximal aerobic and anaerobic activity with heart rates (HR) maintained between 60% and 85% of the maximum rate for the subject's age. At no time did the HR indicate steadystate status within the aerobic conditioning zones for longer than 6 rnin. During the 20 min, activity was intermittent. Although the children ran, swam, or skated, the large musculature of the lower limbs were used in all activities. The work-to-rest ratio was 1:4. Each work bout was 15 sin duration followed by active rest (ie., standing or walking). These exercise prescription factors were carefully monitored by the instructor. At no time were any of the children in a physiological state that they could not exercise and talk comfortably to the instructor or other children. Gymnasium. The core of the gymnasium activity consisted of hockey specific skill development drills as outlined by Pelham et al. (20). Each drill was of equal duration, with each participant performing as many as 20 simulations. ice Rink. Drills similar to those in the gymnasium were performed during the ice session. Swimming Pool. In the pool, subjects swam intervals with HR 60 to 85% maximum. The stroke performed was of the subject's choice. At no time did HR indicate steady state status longer than 6 min.

4 Asthma and Indoor Environments To examine the overall effect of these environments on pulmonary function, a 2 (groups) x 3 (environment) analysis of variance model with repeated measures (ANOVA) was used. The Scheffe post-hoc test was used to locate si&~cant differences between group data. Significant differences were accepted at the alpha level p if less than -05, wherep is the probability that no difference exists. Results Prior to forced pulmonary function pretesting and previous to posttesting, none of the subjects were observed or reported taking medication. Several children with asthma were observed wheezing and coughmg following activity in the ice skating rink. The children reported that these episodes were mild. No severe episodes were reported before or after any activity session. However, several children with asthma took bronchodilator medication postexercise as prescribed by their physician. Positive tests were found in four children with asthma and two children without asthma following activity in the rink. Three children with asthma and two children without asthma had a greater than 20% decrease in FEV, and FEVT following activity in the rink. One child with asthma had greater than a 20% decrease in FEV, following pool activity. In general, children with asthma showed a significant (p <.05) decrease in both FEV, (compared to gymnasium and pool activity) and FEVT% (compared to pool activity) 5 rnin following hockey play (Table 1). Normal lung function was found 5 min following gymnasium and pool activity. In general, children without asthma maintained normal pulmonary function in the three environments. Compared to children without asthma, children with asthma showed a significant (p e.05) decrease in FEV, following hockey play and a significant (p <.05) difference in FEV, following gymnasium activity. Discussion The environment-response data would seem to suggest that swimming at the exe~cise prescription intensity level used in this study does not interfere with lung function of most children with asthma tested. Indeed, these findings tend to support the recommendation by many health professionals that swimming is a healthier activity for children with asthma who wish to improve their cardiovascular and neuromuscular fitness (23). The favorable conditions in this venue include the warm, humid environment of both the air and the water in the heated pool (10). The well ventilated gymnasium environment was also warm and humid, and lung function values of subjects were similar to those in the pool. This might ex- ~ n - ~ ~ r n ~ d ~ c a t i.. o sports activities in well ventilated or in outdoor settings (provided there are no irritants in the atmosphere). However, the major finding of this study was that while subjects performed closely monitored and controlled exercise prescriptions (duration and intensity) in the three environments, only after hockey play did lung function in children with asthma significantly decrease. Reduced lung function values among the children with asthma were associated with the rink environment.

5 Pelham, Holt, and Moss Table 1 Mean Lung Functions After Activity Stated as a Percentage of the Preexercise Value Postexercise Children Children measurement with asthma without asthma Ice rink FEv, FVC FEW Gymnasium FEv, FVC FEVT Swimming pool FEv, FVC FEVT *Significant, p <.05 (compared to children without asthma, same activity).?significant, p <.05 (compared to gymnasium). #Significant, p <.05 (compared to swimming pool). In outdoor environments, prolonged exposure to extreme cold and dry conditions have been identified as precipitators of respiratory dysfunction (13). It has been suggested that the effect of these environmental determinates increase if the child with asthma performs strenuous aerobic activity and hyperpnea is present (10). However, the asthmogenicity of cold and dry conditions should not be restricted to the outdoor environments. considering most indoor ice rinks are insulated and do not effectively exchange air, these facilities remain cold and dry. There are three methodological limitations that must be considered while interpreting the results of this study. First, lung function was measured 5 min post-exercise. Testing at 2-, 5-, and 10-min intervals may capture initial bronchospasm response development and responses occurring after 5 min. Second, although respiratory frequency for all subjects in the three environments during exercise were moderate, specific rates were not recorded. Comparisons of subject's rates and minute ventilation between sporting environments and between children with asthma and children without asthma could generate information regarding the influence of these variables on bronchospasm response. A third limitation was that potential ambient pollutants were not measured. Low concentrations of circulating irritants can be a major influence on lung function in children with asthma (20). This information would have been valuable in regard to the identification of causal agents (21) versus triggers (cold, dry air, and exercises) associated with asthma, particularly in regard to the interactive nature of causal agents and triggers.

6 Asthma and Indoor Environments In respiratory research, attempts have been made to identlfy high risk environments for children with asthma. One line of research has focused on the indoor living environment of children with asthma (6). However, another indoor environment with the potential for triggering asthmatic symptoms and, therefore, a place the child with asthma is at a high risk, is the indoor skating rink. Over the past 30 years, there have been a number of documented cases of acute carbon monoxide (CO) and nitrogen dioxide (NO,) poisoning in Canada (4), the U.S. (3, and Sweden (26) resulting from the release of pollutants into enclosed ice skating arenas during routine ice resurfacing. A number of studies have documented ambient conditions that exist inside ice skating arenas (2,3,7,8,27). High concentrations of CO and NO, have also been found in the blood of hockey players and workers of these facilities in controlled experimentation (1,7, 12, 14-16). As mentioned above, the most often cited prime source of indoor environmental pollution is resurfacing equipment. Many noxious compounds are produced by resurfacing equipment. Although no research is available, particulates and volatile organic compounds (VOC) are other toxic chemicals that may be present in the indoor skating rink. The adverse health effects of particulates have been shown to be quite severe (8, 16, 18,25) and should be of concern. Indeed, the additive or synergistic effects of CO, NO,, particulates, and VOC have not been documented. Considering the populmty of the enclosed ice skating facility in North America and Northern Europe and the current philosophy advocated by many health and medical organizations that participating in activities associated with these facilities will improve the health status of young and old, further experimentation and recommendations on the issue of environmentally-induced asthma in enclosed ice skating rinks is necessary. It is evident that a number of factors can and do influence the health of participants who partake in activities in the indoor arena environment. The available literature has identified components of aii ambient air conditions (temperature and humidity) as possible precipitates. The interactive effects of these factors are not known. It is obvious that much needs to be done to respond to this important health problem. References 1. Berglund, M., L. Bralock, G. Bylin, J.-0. Jonsion, and M. Vakter. Personal NO, exposure monitoring shows high exposure among ice-skating schoolchildren. Arch. Environ. Health. 49: 17-24, Brauer, M., and J.D. Spengler. Nitrogen dioxide exposures inside ice skating rinks. Am. J. Public Health. 84: , Brauer, M., J.D. Spengler, K. Lee, and Y. Yanagisawa. Air pollutant exposure inside ice hockey rinks: Exposure assessment and reduction strategies. In: Safety in Ice Hockey, C.R. Castaidi, P.J. Bishop, and E.F. Hoerner (Eds.). Philadelphia: American Society for Testing and Materials, ~Gadizn f,%b-braiory ~t,ntreferbis-m~i. Carbon monoxide in ice arenas- - British Columbia. Canada Dis. Weekly Rep , Centers for Disease Control. Carbon monoxide exposures at an ice-skating rink-colorado. MMWR. 35: , Dekker, C., R. Dales, S. Bartlett, B. Brunekreef, and Z. Wanenburg. Childhood asthma and the indoor environment. Chest. 100: , Dewailly E., and S. Allaire. Nitrogen dioxide poisoning at a skating rink-quebec. Can. Dis. Weekly Rep :61-62, 1988.

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