Effects of constant-load exercise and high-intensity interval training on reliever medication consumption and peak expiratory flow in individuals with asthma: a randomised controlled trial

Introduction The effect of aerobic training on reliever medication consumption (short-acting β 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. The purpose of the present study was to compare the effects of CLE or HIIT in SABA consumption and PEF improvement during an exercise programme in subjects with asthma. Methods Clinically stable participants were randomised into CLE (n=27; 70–85% of the maximal load (W max )) or HIIT (n=28; 80–140% W max ). The programme lasted 12 weeks (two sessions per week, 40 min per session), and the intensity was based on cardiopulmonary exercise testing (CPET). PEF was assessed before and after each exercise session. SABA was used if PEF was <70%. Clinical control (Asthma Control Questionnaire (ACQ)-6), CPET and aerobic fitness were also assessed before and after the intervention. Results Both 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 group than in the HIIT group (1.6±25.3 versus 10.3±13.7%). Both groups improved aerobic fitness (10.1±12.8% versus 5.7±15.6%) and clinical asthma control; however, only the HIIT group achieved a minimal clinically important difference in the ACQ-6 post-intervention (−0.23±1.06 versus −0.52±0.73 Δ score). Conclusion CLE 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.