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Development of statistical models for predicting muscle and mental activities during repetitive precision tasks

Zadry H. R., Dawal S. Z. M., Taha Z.

International Journal of Occupational Safety and Ergonomics

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2016

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Vol. 22, No. 3

374--383

EN

This study was conducted to develop muscle and mental activities on repetitive precision tasks. A laboratory experiment was used to address the objectives. Surface electromyography was used to measure muscle activities from eight upper limb muscles, while electroencephalography recorded mental activities from six channels. Fourteen university students participated in the study. The results show that muscle and mental activities increase for all tasks, indicating the occurrence of muscle and mental fatigue. A linear relationship between muscle activity, mental activity and time was found while subjects were performing the task. Thus, models were developed using those variables. The models were found valid after validation using other students’ and workers’ data. Findings from this study can contribute as a reference for future studies investigating muscle and mental activity and can be applied in industry as guidelines to manage muscle and mental fatigue, especially to manage job schedules and rotation.

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Anthropometric Database for the Learning Environment of High School and University Students

Dawal S. Z. M., Zadry H. R., Azmi S. N. S., Rohim S. R., Sartika S. J.

International Journal of Occupational Safety and Ergonomics

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2012

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Vol. 18, No. 4

461--472

EN

This paper presents an anthropometric database of high school and university students from Kuala Lumpur,Malaysia. Forty-one high school participants (21 males and 20 females), 13–17 years old, and 143 university students (74 males and 69 females) took part in the study. Twenty-one static body dimensions were measured. The greatest mean differences in the anthropometric data between male and female high school students were found in the sitting elbow height. In addition, a comparison of anthropometric data of male and female university students showed that data for males and females were significantly different, except for buttock–popliteal length, sitting elbow height and thigh clearance. The primary aim of this study was to develop an anthropometric database that could be used as a primary reference in designing products, devices and equipment for ergonomic learning environments.

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The Relation Between Upper Limb Muscle and Brain Activity in Two Precision Levels of Repetitive Light Tasks

Zadry H. R., Md Dawal S. Z., Taha Z.

International Journal of Occupational Safety and Ergonomics

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2011

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Vol. 17, No. 4

373--384

EN

A study was conducted to investigate the effects of repetitive light tasks of low and high precision on upper limb muscles and brain activities. Surface electromyography (EMG) and electroencephalography (EEG) were used to measure the muscle and brain activity of 10 subjects. The results show that the root-mean-square (RMS) and mean power frquency (MPF) of the muscle activity and the mean power of the EEG alpha bands were higher on the high-precision task than on the low-precision one. There was also a high and significant correlation between upper limb muscle and brain activity during the tasks. The longer the time and the more precise the task, the more the subjects become fatigued both physically and mentally. Thus, these results could be potentially useful in managing fatigue, especially fatique related to muscle and mental workload.