ERGONOMIC STUDY OF WORKING ENVIRONMENT AND TOOLS FOR PEOPLE WITH CERVICAL SPINAL CORD INJURY IN A WELFARE TYPE PLANT FACTORY

S. Okahara^1,2, K. Okuda²

Background: In Japan, there is a national policy that promotes working for the elderly and people with disabilities. And there are indoor plant factories as urban agriculture that regardless of the weather. We have been developing a welfare-type plant factory that be able to work for individuals with cervical spinal cord injury (SCI).

Purpose: This study ergonomically analyzes the effects by the developed environment and tools, aimed at helping people with cervical SCI work comfortably. As a trial, we measured changes in work efficiency and physical load while doing actual work in the model plant factory.

Methods: The subjects were five males with C6–C8 SCI. According to the American Spinal Injury Association guidelines, the subjects with cervical SCI had upper motor scores ranging from 16 to 40. The subjects performed the following 3 simulated tasks in the model plant factory, with 150 repetitions of each task: sowing, transplantation, and harvesting. Protocol A introduced a general work environment, Protocol B introduced the developed environment and tools, and the protocol was implemented on another day, with a gap of one month. Working time was measured with a stopwatch from the beginning to the end of each task. A visual analogue scale (VAS) was used to measure fatigue before and after completion of all tasks. Surface electromyography (EMG) was recorded from the beginning to completion of each task for 3 muscles in the dominant upper arm: the upper trapezius (UT), anterior deltoid (AT), and biceps brachii (BB) muscles. The maximum integrated values 1 second from 5-second maximum voluntary contractions performed against manual resistance were measured twice at the end of an experimental day; These values were used to normalize the percentage of maximum voluntary contraction (%MVC), and average %MVC values were calculated for each task. Statistical analysis of differences in work time, VAS, and average %MVC were compared among all subjects using the Wilcoxon signed-rank test. Significance was set at p < 0.05.

Results: Especially in sowing, compared to Protocol A, Protocol B was significantly lower in working time and VAS (p <0.05). There was no significant difference in the average %MVC in UT, AT, and BB in all tasks. In transplanting and harvesting, the working time and VAS tended to decrease.

Conclusion(s): It was found that people with cervical SCI can perform typical work in a welfare-type plant factory. It was also suggested that the developed environment and tools are effective in improving work efficiency and reducing physical fatigue.

Implications: Connect to suggestions for new agricultural employment for people with severe disabilities.

Funding, acknowledgements: The authors received no financial support.

Keywords: Ergonomic, cervical spinal cord injury, work

Topic: Occupational health & ergonomics

Did this work require ethics approval? Yes

Institution: Osaka Prefecture University

Committee: The Ethics Committee of the School of Comprehensive Rehabilitation

Ethics number: 2013-119