Synergistic and distinct effects of expansive posture and nasal breathing on psychological and physiological self-regulation in adolescents.

Adolescents are vulnerable to anxiety and low self-efficacy due to heightened emotional reactivity and immature regulatory systems. Embodied interventions, such as posture adjustment and controlled breathing, have shown promise for enhancing psychological self-regulation, but their synergistic effects in adolescents remain unclear. This study examined the immediate and sustained effects of expansive posture, nasal breathing, and their combination on self-efficacy, anxiety, and autonomic nervous system (ANS) activity in adolescents aged 15–18 years. Participants completed the Trier Social Stress Test, received one of four interventions, and were assessed with self-report questionnaires (General Self-Efficacy Scale; State–Trait Anxiety Inventory-6; n = 138) and continuous electrodermal activity (EDA; n = 62) recorded during the intervention and a subsequent Stroop task. Results showed that expansive posture—alone or combined with nasal breathing—significantly increased self-efficacy, while all three active interventions reduced anxiety compared with controls. Physiological analyses revealed distinct patterns of ANS modulation: nasal breathing alone yielded more stable EDA profiles with lower variability—consistent with enhanced autonomic flexibility in HRV studies—while the combined intervention produced larger autonomic fluctuations, suggesting compensatory responses. These findings highlight the complementary benefits of posture and breathing strategies and support a phased “activate–then–stabilize” approach to adolescent self-regulation.