Photoplethysmography（PPG）is widely used for pulse rate monitors. However, it is difficult to monitor the pulse rate accurately during exercise, because PPG is affected by the body motion. In this study, we attempted to develop a system which controls the contact pressure between body and the PPG sensor, and to remove the motion artifact from the PPG signal by the contact pressure control. Seven healthy subjects without any indication of peripheral arterial disease were participated in this study. They attached the green PPG sensor at their upper arm at three contact pressure conditions; no pressurization, pressurization without control and pressurization with control, and walked on a treadmill at 4 km/h. In the condition of pressurization with control, the contact pressure was maintained at 30 mmHg by the developed system. We evaluated the error of pulse rates during walking as an index of motion artifact. As a result, the average errors at no pressurization, pressurization without control and pressurization with control conditions were 19.6 %, 5.4 % and 3.6 %, respectively. Although there were no significant differences among the conditions, the condition of pressurization with control tended to show the smallest error. In addition, the numbers of subjects with error less than 5% on no pressurization, pressurization without control and pressurization with control conditions were 2, 4 and 6 of 7, respectively. Our results suggest that the contact pressure control system maintaining the optimal contact pressure is useful to remove the motion artifact from the PPG signal.

DESCENTE SPORTS SCIENCE Vol.35/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE