الفهرس 
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Abstract
Asthma is a chronic disorder of the airways that is characterized by reversible airway obstruction, Persistent bronchial hyperresponsiveness and inflammation of airways.
High intensity exercise in asthmatics can results in exercise-induced bronchoconstruction. This is related to two hypotheses of the pathophysiology of EIA. First, airway obstruction may be caused by rapid rewarming of the cool airways following exercise, leading to vascular hyperemia and edema. Secondly, airway dehydration resulting in hypertonicity of the airways can lead to the release of chemical mediators of inflammation such as leukotrienes, which then cause bronchoconstriction. The cysteinyl leukoterienes cause bronchoconstriction in healthy individuals and patients with asthma and are key mediators in the pathogenesis of airway narrowing following EIA.
Exercise training was found to protect against EIB. However, the exact mechanism for this protection is not clear. That may be due to sluggish response of leukotriene to exercise or depletion of leukotriene levels.
The aim of the present study was to test the hypothesis that the post-rehabilitation training program-induced improvement in the incidence and the severity of post-exercise bronchoconstriction is related to change in the level of leukotriene in response to exercise.
20 children known to have EIA, (2 females and 18 males) were included in this study. All the patients have asthma as defined by American thoracic society. All asthmatic children were a symptomatic and their asthma should be clinically stable at the beginning of the study. Corticosteroids were withheld at least 2 weeks before the first day of study. Other antiasthmatic drugs were withheld for at least 8 hours before the day of the study.
The following investigations were carried out
1- Measurement of pulmonary flow rates using Jaeger pneumotach. The baseline pulmonary function (resting) measured included FVC, FEV1, FEV1/FVC% and FEF25%-75%.
2- Exercise challenge test was carried out through a standard protocol of incrementally increasing workloads by using bicycle ergometer. All asthmatic children should have pre-exercise FEV1 greater than 70% predicted in order to perform the exercise challenge. FEV1 was recorded at 5, 10 and 15 min post exercise. The reduction in post-exercise FEV1 was taken as an indicator of response to exercise challenge. Positive response to exercise was defined as 12% reduction in pre-exercise value of FEV1.
3- Measurement of the mean concentration levels of cysteinyl-leukotrienes (C4, D4 and E4) in the induced-sputum during rest and post-exercise by ELISA.
All the above procedures were repeated after 12 –week rehabilitation training program.
The obtained results were statistically analyzed using statistically packed for the social science (SPSS) for windows.
The results of the study showed the following
1- The mean baseline values (L) of pulmonary function FVC, FEV1, FEV1/FVC % and FEF25%-75% (1.96±0.60, 1.84±0.51, 94.66±7.08 and 2.14±0.85) were within normal range before training program (Pre-exercise).
2- Response to exercise before training
• All asthmatic children were responder to exercise (have % fall in FEV1 12%) before training program.
• A reduction (% fall) in FEV1 was 25.57±11.59 post-exercise before training program.
3- Baseline pulmonary function (L) FVC, FEV1, FEV1/FVC% and FEF25-75% were (2.00±0.40, 1.92±0.37, 95.82±5.10 and 2.11±0.65) respectively increased (improvement) after training program but this increase did not reach to the level of significance. A significant increase in the mean% predicted FEV1 was observed after training program.
4- Response to exercise after training program (p = 0.05).
• 12 asthmatic children were non responder to exercise and had % fall in FEV1< 12%, and 8 asthmatic children were responder to exercise and had % fall in FEV112% post-exercise after training program.
• A reduction (% fall) in FEV1 was 10.29±16.85 post-exercise after training program.
• A significant decrease (improvement) in % fall in FEV1 was detected after training program. (P= 0.00)
• Asthmatic children have an improvement in EIB (a degree of protection against EIB). 16 cases have % protection > 50%, and 4% cases have % protection <50%.
5- Cysteinyl-leukotrienes
• The value of sputum cys-LTs concentrations (pg/ml) levels were 338.50±210.85 pre-exercise, and 536.65±242.02 post-exercise before training program.
• The value of sputum cys-LT concentration (pg/ml) levels were 296.7±95.42 pre-exercise, and 397.80± 143.69 post-exercise after training program.
• A significant decrease in the mean concentration levels of sputum cys-LTs of asthmatic patients in response to exercise was observed after training program. (p = 0.02).
• A significant decrease in the % change of sputum cys-LT concentration levels was detected after training program (p=0.04).