Influence of Posture, Breathing and Gender on Sinus Arrhythmia

Respiratory sinus arrhythmia represents a key marker of vagal control over heart rate and offers insight into autonomic regulation under everyday physiological conditions. This work examines how posture, breathing patterns, and gender shape variations in heart rate and oxygen saturation using a non-invasive approach. A cross-sectional observational design was applied to a cohort of 250 healthy adults aged 18 to 45 years, with measurements obtained through pulse oximetry during different breathing patterns and postural states. The observations show that deep and slow breathing is associated with a lower heart rate and improved oxygen saturation, suggesting enhanced parasympathetic activity. Changes in posture from supine to standing are accompanied by a gradual rise in heart rate, consistent with increased sympathetic activation. Gender-based comparisons indicate marginally higher heart rates and lower oxygen saturation values among female participants. Together, these findings highlight the sensitivity of autonomic balance to simple physiological factors and support the relevance of breathing control and posture in modulating sinus arrhythmia, while also pointing to inherent gender-related variations in autonomic function.