الفهرس 
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Abstract
Asthma is a chronic inflammatory disorder of the airways. Impairment of exercise tolerance is a common problem in patients with asthma.
Exercise is a potent stimulus for provoking asthma symptoms in children. For this reason children with asthma may avoid exercise which may in turn be detrimental to their physical and social conditioning.
Even though every child suffering from asthma is prone to exercise-induced bronchospam, avoiding all physical exertion is not a solution to the problem. Rehabilitation programs, in which exercise prescription is a keystone, are recommended and widely applied in asthmatic patients with a goal of improving physical fitness, self confidence and quality of life. As well as, achieving physiological benefits and better management of the disease. The fundamental basis of these effects of exercise training in asthma remains unclear. So the aim of the present work was to determine the effect of exercise training on exercise capacity and pulmonary physiology in asthma.
Twenty five children with mild-moderate asthma were enrolled in a 12-week training program. All children included in the study subjected to:
1- Pretraining assessment.
2- Training program.
3- Post-training assessment.
1- Pretraining assessment
- Assessment of clinical severity of asthma disease by clinical severity score and airway reactivity score.
- Assessment of quality of life using juniper AQLQ.
- Assessment of pulmonary flow rates included: FEV1, FVC, FEV1/FVC%, FEF25%, FEF50%, FEF75%, and FEF25-75% by using dry spirometer (Jaeger) with automatic dosimeter for methacholine inhalation challenge.
- Methacholine inhalation challenge was performed to assess direct bronchial hyperresponsiveness. The five-breath dosimeter protocol was used, the provocational dose of methacholine causing 20% DROP in FEV1 (PD20-FEV1) was obtained.
- Determination of respiratory muscle pressure PImax, PEmax and the occlusion pressure at 0.1sec (P0.1 max), as an indicator of the respiratory drive, by measuring the shutter pressure at the mouth using a respiratory module system.
- Assessment of ventilation: and MVV using dry spirometer (Jaeger).
- Measurement of resting heart rate.
- Exercise challenge test and assessment of the physical work capacity: each child performed incremental exercise challenge on bicycle ergometer (Jaeger ER900). The load was increased by 20 watt at 2 min interval until reaching a heart rate equal to 80-90% of predicated maximal heart rate. Then the child continued to exercise at that work load for further 5 min. heart rate and blood pressure values at each work load were obtained. The test was considered positive when the post-exercise reduction in FEV1 was 12%.
2- Training program
Children had undertaken physical training on a caliberated cycle ergometer (Jaeger ER900) twice a week for 12 weeks. Each training session lasted for 45 min, started by 2 min worming up at zero watt then the load was increased by 15 watt at two minutes interval till heart rate equal to 75% of predicted maximal heart rate was reached, then the child continued to exercise at that load for further 5min. This was repeated 3 times/session with breathing exercises in between.
3- Post training assessment
At the end of the 12 weeks, reevaluation of the pretraining obtained parameters was done.
The results revealed the following
- Significant improvement in the clinical severity score and airway reactivity score.
- Significant improvement in the health related quality of life.
- Significant increase in the mean values of the baseline pulmonary function: FEV1, FEV1/FVC%, FEF25%.
- Significant improvement in the airway hyperresponsiveness to methacholine as detected by the significant increase in the mean value of PD20-FEV1.
- Significant increase in the mean values of respiratory muscle pressure PImax, PEmax, P0.1max.
- Significant increase in the mean of the basal value of MVV and significant decrease in the ventilatory requirements during exercise as detected by the decrease in with each load during exercise challenge.
- Significant decrease in the mean values of heart rate and blood pressure with each load during exercise challenge.
- Significant protection against the development of post-exercise bronchoconstriction, with significant increase in the physical work capacity.