Exercise-induced asthma in children.

"If from running, gymnastic exercises, or any other work, the breathing becomes difficult, it is called Asthma (<XmJlCX)". Aretaeus the Cappodician; lst Century AD [1]. Exercise-induced bronchoconstriction (EIB) was long ago recognized as a manifestation of asthma [1], and exercise-induced asthma (EIA) is a common presentation of childhood asthma. BACKER and ULRIK [2] reported that 16% of 494 healthy Danish children and adolescents had a fall in forced expiratory volume in one second (FEY 1 ), of 10% or more after exercise test, and Em is reported to occur in 70-80% of asthmatic children and adults [3]. EIA represents a major impairment of the everyday life of asthmatic children, influencing their self-perception, as they appraise themselves to a major extent by their successes in physical skill and mastery. Based upon the 1988 National Health Interview Survey in USA, TA YLOR and NEWACHF.CK [4] recently reported that of 2.7 million American children with asthma, 2.6% were unable to conduct major activities, compared to 0.3% of all children without asthma. Approximately 30% of asthmatic children had some limitations in activity, compared to 4.5% of children without asthma [4]. These limitations in physical activity remain a major obstacle to the asthmatic child's social and physical functioning. When studied in a standardized way, Em may be regarded as a measure of nonspecific bronchial hyperreactivity [5]. EIB is thought to be elicited by mediator release, provoked by respiratory heat and water loss, causing a change in osmolality of the pericilliary fluid lining the respiratory tract [3]. Em is, therefore, considered an indirect measure of nonspecific bronchial responsiveness, whereas bronchial responsiveness measured by methacholine or histamine inhalation is considered a direct measure of bronchial responsiveness [6]. EIB is usually measured by the reduction in FEY 1 from preto post-exercise with a submaximal load. Running on a motor driven treadmill for 6 min. with a steady-state heart rate of 170-190 beats·min·', is a commonly used test. Running is usually more suitable than using a bicycle, as the muscles used during running are better trained as a result of daily life activity than those used during cycling. A reduction in FEV1 of 15% or more after exercise is usually taken as a sign of EIA [7, 8]. Sometimes 10%