The Effectiveness of A Slow-Paced Diaphragmatic Breathing Exercise in Children's Daily Life: A Micro-Randomized Trial.

Objective: Breathing exercises have been proposed as an effective intervention to improve subjective well-being and manage anxiety symptoms. As they are comparatively easy to learn and to implement, breathing exercises may be particularly beneficial for children. Although breathing exercises are ultimately supposed to provide salutary effects in individuals' everyday lives, immediate effects of breathing exercises in naturalistic contexts have received limited empirical attention. The purpose of this study was to examine immediate effects of slow-paced diaphragmatic breathing on negative affect as well as on relaxation in an ecologically valid setting. To that end, we conducted a micro-randomized trial in children's daily life.

Method: On each of 15 days, children ( = 171, aged 9-13 years, 54% female) were randomized to different conditions: performing a video-guided slow-paced diaphragmatic breathing exercise (experimental condition), watching a different video (active control condition), or a passive control condition.

Results: The breathing exercise had no immediate effects on negative affect or relaxation compared to both control conditions. However, in situations when children reported higher levels of worries than usual, relaxation was higher when children performed the breathing exercise compared to the passive control condition. Compared to the active control condition, the breathing exercise did not result in higher levels of relaxation in situations when children worried more than normally.

Conclusions: Findings highlight that context-specific factors can modulate the effectiveness of breathing exercises and should be taken into account to tailor interventions to individuals' needs.