Post-Infectious Bronchiolitis Obliterans (PIBO) is an irreversible obstructive lung disease characterized by subepithelial inflammation and fibrotic narrowing of the bronchioles after lower respiratory tract infection. This disease is diagnosed mainly in children, more frequently before the age of 2 years. Due to symptoms such as dry cough and dyspnea sensation, most of these patients have low levels of physical activity compared to healthy individuals. Physical activity can positively influence oxygen consumption, muscle strength, and quality of life. High levels of oxygen consumption are associated with a lower risk of respiratory disease and hospitalization. High-intensity interval training (HIIT) may be an effective way to improve oxygen consumption, muscle strength, and quality of life in patients with chronic diseases. HIIT has been shown to produce less dyspnea sensation and to be more entertaining in children and adolescents with respiratory disease compared to continuous training. Thus, the investigators propose to perform telematically real-time guided training to reduce travel times and additional costs to patients.

Objective: To analyze the effects of a telematically supervised high-intensity intervallic training program on aerobic fitness, as well as functional/clinical outcomes in patients with PIBO.

Methods: Randomized controlled trial with two groups. Exercise group: 16-week HIIT training conducted telematically; Control group: will follow the routine physician's recommendations. Patients will be recruited at Vall D'Hebrón University Hospital (Barcelona), Niño Jesús University Hospital (Madrid), and Donostia Universitary Hospital (San Sebastián). Criteria for participation: (I) Diagnosis of PIBO; (II) Clinically stable at the time of the assessments; (III) Age between 6 to 20 years old.

Inclusion Criteria:

• Diagnosis of Postinfectious bronchiolitis obliterans;
• Clinical stability at the time of the assessments;
• Age between 6 and 20 years old.

Exclusion Criteria:

• Symptoms of pulmonary exacerbation during the last four weeks;
• Diagnosis of other cardiorespiratory diseases leading to symptoms of persistent respiratory dysfunction;
• Difficulty in comprehension or musculoskeletal alterations that may influence the assessments;
• Pregnancy;
• Transplant list inclusion.

The investigators will collect patients' personal data and clinical history by means of the information delivered by the participating hospital. These data will be stored and coded in an Excel file in order to protect confidentiality before, during and after the study. All information will be entered and stored electronically in the institutional platform REDCAP hosted on the hospitals' server.

After completion of study, the data will be stored for as long as necessary to meet any possible responsibilities derived from the study.

Access will be given only to the researchers of the study.

The evaluators and care providers will be masked to the allocation of the patients. Given the nature of the intervention, it is not possible to mask patients or monitors in charge of supervising the execution of the exercise training.