IntroductionThe effect of aerobic training (AT) on reliever medication consumption (short-action beta-2 agonist (SABA)) and peak-expiratory flow (PEF) in participants with asthma is poorly known. The comparison between constant-load exercise (CLE) and high-intensity interval training (HIIT) in these outcomes has never been tested.PurposeTo compare the effects of CLE or HIIT in SABA consumption and PEF improvement during an exercise program in subjects with asthma.MethodsClinically stable participants were randomized into CLE (n=27; 70–85% of the maximal load (Wmax)) or HIIT (n=28; 80–140%Wmax). The program lasted 12 weeks (twice/week, 40 min/session), and the intensity was based on cardiopulmonary exercise testing (CPET). The PEF was assessed before and after each exercise session. SABA was used if the PEF was <70%. Clinical control (Asthma Control Questionnaire (ACQ-6)), CPET, and aerobic fitness were also assessed before and after the intervention.ResultsBoth groups were similar at baseline. CLE and HIIT reduced SABA consumption throughout the intervention (p<0.05). Before training, 14 patients required SABA before exercising, but only one needed it after the intervention. Changes in post-exercise PEF were lower in the CLE than in the HIIT (1.6±25.3versus10.3±13.7%). Both groups also improved aerobic fitness (10.1±12.8versus5.7±15.6%) and clinical asthma control; however, only the HIIT group achieved a minimal clinically important difference in the ACQ post-intervention (−0.23±1.06versus−0.52±0.73 delta score).ConclusionCLE and HIIT reduced SABA consumption; however, only HIIT increased PEF and asthma clinical control after the intervention. These results reinforce the importance of exercise training in moderate-to-severe asthma.