In-Ear Pulse Wave Amplitude Recordings During Synchronized Walking

One way to improve hemodynamic efficiency is the synchronization of the stepping with the diastolic phase of the cardiac cycle (diastolic stepping) minimizing peak pressures on the heart level. At head level, we expect maximized blood flow in diastolic stepping and minimized blood flow in systolic stepping. This study aims to verify suggested blood flow patterns via analysis of the pulse wave (PW) amplitudes in the ear during synchronized walking. Four participants (2 men, 2 women, 27 ± 3 years) walked on a treadmill at a comfortable speed, guided by auditory signals (Pulson, USA) to perform diastolic and systolic stepping. PW amplitudes were continuously measured in the ear using an optosensor (TCRT1000,Vishay, USA) and compared to heart rate (HR) from an ECG chest strap (Movesense, Finland). Results showed that the PW amplitude increased by 20 ± 16% across all subjects during diastolic stepping compared to systolic stepping, with lower HRs detected from the optosensor (0.73 ± 1.4 beats/min) than from the ECG. The findings suggest that synchronized walking modulates PW amplitude during diastolic stepping with different extent across subjects.