0093 Acute Effects of Diaphragmatic Breathing on Circulatory Dynamics and Autonomic Function During Sleep in Young Men

Introduction Increased arterial stiffness during rest and blood pressure (BP) during sleep are independent risk factors for cardiovascular disease (Boutouyrie et al.2021, Kario et al.2019). Slow, deep breathing is a useful nonpharmacological intervention to control hypertension (Chang et al.2013). However, the acute effects of diaphragmatic breathing before sleep on arterial stiffness during rest and BP during sleep are unknown. In this study, we investigated the acute effects of diaphragmatic breathing before sleep on arterial stiffness, BP, and cardiac autonomic function in young men. Methods Fifteen healthy young men (age: 20.0 ± 0 years, Height: 170 ± 5 cm, Weight: 56 ± 3 kg) participated in this study and underwent two separate sessions in a randomized controlled crossover design: 4-4-8 breathing (BT) protocol (12 consecutive breaths of 4 seconds of inhalation, 4 seconds of pause, and 8 seconds of exhalation through the nose) and control (CON) without 4-4-8 breathing. Brachial-ankle pulse wave velocity (PWV) reflected systemic arterial stiffness and carotid-femoral PWV reflecting central (aortic) arterial stiffness measured using an automated pulse wave testing device. BP was measured simultaneously using an automated oscillometric device. Autonomic function was measured from high-frequency (HF) and low-frequency (LF) components by HR variability spectral analysis. Arterial stiffness, BP, HF, and LF were measured before (baseline) and 30 and 60 min and 24 hours after the 4-4-8 breathing technique. BP, HF, and LF were measured while sleeping. Results There was a significant decrease in the baPWV and LF at 30 min after the BT trial compared to baseline values (P< 0.05). cfPWV on both trials was unchanged. There was a significant increase in the HF at 30 min after the BT trial compared to baseline values (P< 0.05). BP and LF during sleep were lower in the BT trial than in the CON trial (P< 0.05). HF during sleep was higher in the BT trial than in the CON trial (P< 0.05). Conclusion A novel finding of this study is that practicing slow, diaphragmatic breathing with relatively long exhalation times may reduce arterial stiffness during rest and BP during sleep through activation of the parasympathetic nervous system. Support (if any)