Relationship of bronchodilator response with oxygen pulse and ventilatory threshold in children with asthma: the effect of body composition and progressive aerobic activity in an environment with low humidity

Asthma is a leading cause of chronic illness in children, impacting heavily on their daily complications. The purpose of the present study was to relationship bronchodilator response (BDR) with oxygen pulse (OP) and ventilatory threshold (VT) in asthma children with various body compositions during progressive aerobic activities. 25 obese children (BMI>25 and %fat>30)with asthma(10 subjects), and healthy children (15 subjects) and 25 lean children(BMI<20 and %fat<20) with asthma(13 subjects), and healthy children (7 subjects) performed an exercise protocol in a constant temperature environment 2 ± 22 ° C and humidity (5 ± 35%). During exercise, the steady-state levels of cardio-respiratory parameters were measured using gas analyzer (K4B2). The results showed that after a progressive aerobic activity, values peak oxygen consumption(vo2peak) ​​, bronchodilator(BDR), oxygen pulse(OP) and ventilatory threshold(VT) in lean and obese asthmatic children were lower than in healthy lean and obese children. In addition, lean children with asthma had lower VT and higher VO2peak, OP and BDR values​​, as compared obese asthmatic children. Between BDR and VT in lean and obese asthmatic children an inverse relationship between BDR and OP and a direct link to asthma in obese children and obese asthmatic children, there was a negative relationship non-significant. Compared with lean children, asthma, obesity as an additional load will affect lung function and increase the pressure on childhood asthma. Therefore, we can accept that obesity may limit performance of exercise in childhood asthma.