Determinants of exercise capacity in children and adolescents with severe therapy-resistant asthma.

Objective: To evaluate the exercise capacity of children and adolescents with severe therapy resistant asthma (STRA) aiming to identify its main determinants.

Methods: Cross-sectional study including individuals aged 6-18 years with a diagnosis of STRA. Clinical (age and gender), anthropometric (weight, height and body mass index) and disease control data were collected. Lung function (spirometry), cardiopulmonary exercise testing (CPET) and exercise-induced bronchoconstriction (EIB) test were performed.

Results: Twenty-four patients aged 11.5 ± 2.6 years were included. The mean forced expiratory volume in one second (FEV) was 91.3 ± 9.2%. EIB occurred in 54.2% of patients. In CPET, the peak oxygen uptake (O) was 34.1 ± 7.8 mL kg min. A significant correlation between ventilatory reserve and FEV ( = 0.57;  = 0.003) was found. Similarly, there was a significant correlation between CPET and percent of FEV fall in the EIB test for both /O ( = 0.47;  = 0.02) and /CO ( = 0.46;  = 0.02). Patients with FEV<80% had lower ventilatory reserve ( = 0.009). In addition, resting heart rate correlated with O (r=-0.40;  = 0.04), /O ( = 0.46;  = 0.02) and /CO ( = 0.48;  = 0.01).

Conclusions: Exercise capacity is impaired in approximately 30% of children and adolescents with STRA. The results indicate that different aspects of aerobic fitness are influenced by distinct determinants, including lung function and EIB.