Isa Halim

Assessment of muscle fatigue associated with prolonged standing in the workplace.

Objectives The objectives of this study were to determine the psychological fatigue and analyze muscle activity of production workers who are performing processes jobs while standing for prolonged time periods. Methods The psychological fatigue experienced by the workers was obtained through questionnaire surveys. Meanwhile, muscle activity has been analyzed using surface electromyography (sEMG) measurement. Lower extremities muscles include: erector spinae, tibialis anterior, and gastrocnemius were concurrently measured for more than five hours of standing. Twenty male production workers in a metal stamping company participated as subjects in this study. The subjects were required to undergo questionnaire surveys and sEMG measurement. Results Results of the questionnaire surveys found that all subjects experienced psychological fatigue due to prolonged standing jobs. Similarly, muscle fatigue has been identified through sEMG measurement. Based on the non-parametric statistical test using the Spearmans rank order correlation, the left erector spinae obtained a moderate positive correlation and statistically significant (rs = 0.552, p < 0.05) between the results of questionnaire surveys and sEMG measurement. Conclusion Based on this study, the authors concluded that prolonged standing was contributed to psychological fatigue and to muscle fatigue among the production workers.

Development of Prolonged Standing Strain Index to Quantify Risk Levels of Standing Jobs

Abstract Many occupations in industry such as metal stamping workers, electronics parts assembly operators, automotive industry welders, and lathe operators require working in a standing posture for a long time. Prolonged standing can contribute to discomfort and muscle fatigue particularly in the back and legs. This study developed the prolonged standing strain index (PSSI) to quantify the risk levels caused by standing jobs, and proposed recommendations to minimize the risk levels. Risk factors associated with standing jobs, such as working posture, muscles activity, standing duration, holding time, whole-body vibration, and indoor air quality, were the basis for developing the PSSI. All risk factors were assigned multipliers, and the PSSI was the product of those multipliers. Recommendations for improvement are based on the PSSI; however, extensive studies are required to validate their effectiveness.

Development of a Decision Support System for Analysis and Solutions of Prolonged Standing in the Workplace

Background Prolonged standing has been hypothesized as a vital contributor to discomfort and muscle fatigue in the workplace. The objective of this study was to develop a decision support system that could provide systematic analysis and solutions to minimize the discomfort and muscle fatigue associated with prolonged standing. Methods The integration of object-oriented programming and a Model Oriented Simultaneous Engineering System were used to design the architecture of the decision support system. Results Validation of the decision support system was carried out in two manufacturing companies. The validation process showed that the decision support system produced reliable results. Conclusion The decision support system is a reliable advisory tool for providing analysis and solutions to problems related to the discomfort and muscle fatigue associated with prolonged standing. Further testing of the decision support system is suggested before it is used commercially.

Analysis of Time-to-Fatigue for Standing Jobs in Metal Stamping Industry

In metal stamping industry, almost all jobs are practically to be performed in standing position. Standing in a long period of time can lead to muscle fatigue. The objective of this study was to determine time-to-fatigue in the erector spinae, tibialis anterior, and gastrocnemius muscles of twenty production workers in a metal stamping company. The muscles activity was concurrently measured using surface electromyography (sEMG) during beginning, mid, and end of working sessions. Results of study found that gastrocnemius muscle fatigued earlier during all working sessions. In addition, working at the end of working session showed earlier fatigue than the beginning and mid of work days. The study concluded that standing in a long period of time is a cause to muscle fatigue experienced by the production workers.

Analysis of muscle fatigue associated with prolonged standing tasks in manufacturing industry

In most assembly lines in manufacturing industry and service occupations, employees may experience pain and discomfort associated with long periods of standing. Prolonged standing tasks in manufacturing industry may lead to musculoskeletal disorders including pain, increased fatigue and stiffness in active muscles. The aims of this study are to determine subjective fatigue experienced by male Malaysian operators in metal stamping industry, and assess muscle fatigue in their lower extremities. Ten production operators of the industry participated in the study. Muscle fatigue has been analyzed using surface electromyography (sEMG) whereby six muscles such as left and right erector spinae muscles, left and right tibialis anterior muscles, and left and right gastrocnemius muscles were simultaneously measured. On the other hand, the subjective fatigue was assessed through questionnaire surveys. Results of questionnaire surveys found that all operators involved in the study reported that they experienced muscle fatigue due to prolonged standing tasks. Result obtained from sEMG measurement shows similar trend with the conclusion derived from surveys. Workers who experienced fatigue recorded a decreased average mean.

A Plug Assembly Line: An Assessment of Workstation Design and Working Posture

In most industry, assembly line job environments such as workstation design and working posture are factors contribute to workers’ performance. Workstation design such as: standing or sitting, the use of tools such as jig and the height of working table are influencing worker’s productivity. Meanwhile, working posture such as: position of body: arm and wrist, neck, trunk and leg determine comfortability and safe posture while working. These aspects also play a significant role in productivity.

Preliminary Investigations on the Reduction of Foot Pressure Measurement and Muscle Activity with Different Insole Materials

Standing for long periods of time has been recognized as a potential contributor to muscle fatigue. When a person is performing activities in prolonged standing and wearing ineffective material of shoe insole, not only lead to muscle fatigue but can even cause injuries in the long term. The objective of this study is to determine the effects of two types of shoe insole materials; Ethylene Vinyl Acetate (EVA) and a combination of polyurethane (PU) and poron on muscle activity and foot pressure. The analysis of muscle fatigue was performed using surface electromyography (sEMG) while pressure under the foot was measured using FScan device. Results of comparison found that the two types of shoe insole materials showed significant difference (p-value < 0.05) in electromyography signals (µV) in the left and right gastrocnemius muscle while there are significant reductions on the peak pressure measured from the foot pressure measurement. It can be concluded that the combination of PU and poron is an effective material to be used a shoe insole for a person who is exposed to prolonged periods of standing.