Background – Asthma is a chronic inflammatory disorder affecting millionsglobally, with symptoms including wheezing, chest tightness, and shortnessof breath. Regular physical activity can mitigate these symptoms; however,the effectiveness and safety of HIIT for asthmatics remain underexplored.This study addresses this gap by examining HIIT's impact on asthmaticindividuals, focusing on pulmonary function, FeNO levels (an inflammationmarker), and exercise tolerance.Materials and MethodsFourteen adult males, divided into asthmatic (n=7) and healthy control (n=7)groups, underwent a two-week HIIT protocol. Pulmonary function wasassessed using peak expiratory flow (PEF), forced vital capacity (FVC), andforced expiratory volume in one second (FEV1/FVC ratio). FeNO wasmeasured with a portable device, and exercise tolerance was evaluatedthrough a progressive exercise test on a cycle ergometer to determine peakoxygen uptake (VO2peak), carbon dioxide output (VCO2peak), ventilation(VE), and time to exhaustion (TTE). Statistical analysis was performed usingANOVA with repeated measures.ResultsThe results indicated significant differences between groups in FeNO, VO2peak, TTE, and peak work rate (WR), with no significant changes inpulmonary function measures. Asthmatics showed a marked improvement inTTE and peak WR post-HIIT, with mean FeNO levels and pulmonaryfunction measures remaining unchanged from baseline. Specifically, postHIIT, asthmatics achieved higher VE, VCO2, TTE, and peak WR,demonstrating improved exercise tolerance and ventilation withoutexacerbating lung inflammation.ConclusionHIIT was well-tolerated by individuals with asthma, leading to significantimprovements in exercise tolerance and ventilation without negativelyimpacting pulmonary function or increasing lung inflammation. Thesefindings suggest HIIT as a safe and effective exercise modality for asthmatics,potentially aiding in better asthma management through enhanced physicalfitness and exercise capacity.