Short and medium-term effects of an online behaviour change intervention to promote physical activity in adults with asthma: a randomized controlled trial

<bold>Background:</bold> Online behaviour change interventions (OBCI) have been poorly investigated in adults with asthma. <bold>Aims:</bold> To investigate the short- and medium-term effectiveness of an OBCI in improving physical activity (PA), sedentary behaviour (SB), and health-related outcomes in adults with asthma. <bold>Methods:</bold> Adults with stable asthma (41±11 years, 31±6 Kg/m², FEV₁ 78±20%predicted) were assessed at baseline, post-intervention, and 6-month follow-up. After randomization, both groups (control [CG;N=25] and intervention [IG;N=26]) received an educational program, and the IG also received an OBCI for 3 months. PA and SB were evaluated by accelerometry. Asthma control, quality of life, motivational regulation for PA, and basic psychological needs for exercise were assessed by questionnaires. <bold>Results:</bold> The IG increased steps/day during the intervention (p<0.001); however, there was no significant change in PA or SB when comparing groups after intervention (p≥0.19). Participants from the IG increased motivational regulation and basic psychological needs (autonomy and competence) to exercise compared to the CG (p≤0.03). A higher proportion of participants from IG met the minimal important difference for asthma control and quality of life in the short term compared to the CG (p≤0.03). There was no between-group differences at 6-month follow-up (p>0.05). <bold>Conclusion:</bold> This OBCI had no additional value to the educational program in improving PA or SB. However, it improved asthma control and quality of life, supported basic psychological needs for exercise, and conducted participants to increase motivational regulation for PA in short-term.