Physical and Physiological Synchrony Between Care Worker and Care Recipient During Care Operation

Musculoskeletal disorders are a widespread affliction among nurses at nursing-care facilities in general. Nursing proficient skills are supposed to make the disorders reduce and also to lead to tender care for the care recipients. Tacit knowledge such as "proficient skills" and "knacks" in nursing care skills seems not to be applied by care worker alone but by the interaction between care worker and care recipient. The purpose of this study is to examine the physical and physiological synchrony between care worker and care recipient during care operation. It is also to reveal the relationship between the synchrony and physical loads, and the relationship of cerebral activities between them. Experiments of the care operations were carried out in the care worker-recipient pairs. In the experiments the care recipient gave two kinds of roles. One was to act a physically unimpaired person, and the other was to act a bedridden person that was unable to move on his/her own. The body motions, muscle loads, and cerebral activities of the care worker and care recipient were measured using two sets of motion capture, EMG device, and near-infrared spectroscopy (NIRS), respectively. Experimental results indicated that the muscle loads of care worker decreased when the temporal changes of physical and physiological data of the care worker and care recipient got into synchronization. Furthermore, in that case the cerebral activities of the care recipient were synchronized with those of the care worker.