Effectiveness of a HIIT exercise program in post-infectious bronchiolitis obliterans: preliminary results from a RCT

<bold>Introduction:</bold> Although high-intensity interval training (HIIT) has shown effectiveness in improving aerobic fitness across various conditions, its impacts on individuals with post-infectious bronchiolitis obliterans (PIBO) remain unexplored. <bold>Aim:</bold> To evaluate the impact of a remotely supervised HIIT program on aerobic fitness, lung function, muscle strength, functional capacity, body composition, and quality of life in individuals with PIBO. <bold>Methods:</bold> This multicentre, randomized controlled trial with blinded evaluator enrolled individuals aged 6 to 20 years diagnosed with PIBO. The experimental group (EG) underwent two 30-min sessions of HIIT per week for 16 weeks, while the control group (CG) adhered to routine recommendations. Both groups were assessed before and after the intervention. The primary outcome was peak oxygen consumption (VO2peak), assessed via cardiopulmonary exercise testing. Secondary outcomes were FEV1, muscle strength (dynamometry), functional capacity (30-second sit-to-stand test - STS30), body mass index, and quality of life (SGRQ). <bold>Results:</bold> A total of 29 patients (EG=13; CG=16), 17 males, were included. The mean age was 14.0±3.7 years, FEV1 56.7±16.0% and VO2peak 37.2±7.6mL/kg/min. The HIIT intervention increased the STS30 (mean diff.=3.07, p=0.03). A promising, although still not statically significant effect, was seen for VO2peak (mean diff.=3.09, p=0.08). No differences were found for the other variables. <bold>Conclusions:</bold> The preliminary results indicate promising effects of the HIIT intervention on functional capacity and aerobic fitness. With the desired sample size and statistical power, significant differences in STS30 and VO2peak are expected.