Participants
Participants with a diagnosis of mild‐to‐moderate asthma and CF, as well
as healthy children and adolescents were selected. General inclusion
criteria was children and adolescents aged 7–18 years. General
exclusion criteria were: (i) respiratory exacerbations 4 weeks prior to
the evaluation, and (ii) presence of musculoskeletal condition or any
other disorder that influences exercise capacity. Patients with
mild‐to‐moderate asthma were selected consecutively in the outpatient
clinics of the Pediatric Pulmonology department (Hospital Universitario
Infantil Niño Jesús). Specific inclusion criteria were: (i) asthma
diagnosis with at least 6 months of evolution, (ii) exercise‐associated
symptoms (score 0–1 in question 2 of the asthma control test (c-ACT)25, or score 2–3 in question 7 of the asthma control
in children (CAN) 26. Specific exclusion criteria
were: (i) need for increased use of basal medication, inhaled
corticosteroid dose, long‐acting β2 agonist, leukotriene receptor
antagonists, oral corticosteroids or omalizumab, (ii) respiratory
exacerbation requiring systemic corticosteroids in the last 3 months or
presence of mild exacerbations in the last month (need for a
higher-than-usual dose of short-acting beta-agonist), (iii) irregular
use of the medication prescribed by the physician, and (iv) presence of
another chronic respiratory or cardiac disease. No medications were
withdrawn during the test days and patients kept their usual treatment
regimen. Participants with CF were also recruited at Hospital Niño Jesus
in Madrid. Specific inclusion criteria was a genetic diagnosis of CF.
Specific exclusion criteria were: (i) having severe lung deterioration,
as defined by an FEV1 lower than 50% of the predicted,
and (ii) presenting unstable clinical condition (i.e., hospitalization
within the previous 3 months or exacerbation in the previous 4 weeks).
None of the patients included received CF modulator therapy at the
moment of evaluation.
Healthy children were recruited from schools in the same district as the
hospital to avoid significant differences in environmental conditions
(levels of air contamination, presence of environmental allergens, and
pollen). Children were selected by convenience sampling, using a
covariate adaptive randomization to reduce selection bias. Specific
eligibility criteria were: (ii) attending schools in the same district
as the hospital, and (ii) having no positive answers in the
International Study of Asthma and Allergies in Childhood (ISAAC)
questionnaire 27. Specific exclusion criteria were the
diagnosis of cardiac, neurological, or chronic respiratory diseases that
would impair cardiorespiratory fitness.