Effect of Sitting Posture on Systolic Phase of Cardiac Cycle Derived from Strain Gauge based Ballistocardiogram

Ballistocardiography (BCG), a technique detecting subtle vibrations from cardiac activity, offers insights into heart functionality. The BCG waveform features distinct points of systolic phase (H, I, J, K), signifying ventricular contraction initiation (H), blood acceleration (I), peak blood flow (J), and aortic valve closure (K). This study explores the effect of various on the systolic phase of the cardiac cycle using a BCG system with a strain gauge sensor integrated into a chair. Ten healthy subjects, aged 27±3, were analysed across five postures: upright, hunched, backward lean, left lean, and right lean. Variations in systolic interval (H-K) were significant; compared to upright posture, upper body hunched and leaning backward showed prolonged H-K intervals (p < 0.05), with a more rapid ejection phase (H-I) compared to upright and hunched postures (p < 0.05). Despite posture-induced variations, the average heart rate remained consistent across various postures (p > 0.05). Cardiac interval derived from BCG (J-J) shows 99.6% accuracy in cardiac interval estimation compared to reference ECG (R-R) within the selected window. This study highlights the potential of a cost-effective and unobtrusive strain gauge based BCG system in assessing the impact of posture on the systolic phase of the cardiac cycle. Understanding the influence of posture can be useful in developing personalized posture management strategies. This could be valuable for the unobtrusive and long-term assessment of heart function to optimize cardiovascular well-being, potentially benefiting patients with cardiovascular conditions.