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Ergonomic Risk Factors for Cumulative Trauma Disorders in VDU Operators

Turhan N., Akat C., Akyuz M., Cakci A.

International Journal of Occupational Safety and Ergonomics

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2008

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Vol. 14, No. 4

417--422

EN

The objectives of this study were to investigate the rate of cumulative trauma disorders (CTDs) in the upper body and to describe the associations of such disorders with ergonomic parameters in a group of data entry operators. A total of 173 data entry operators volunteered to take part in the study. Questionnaires were used to investigate their medical history. Diagnoses of CTDs were made with clinical tests. A visual posture analysis of the workers and an ergonomic analysis of workstations and workload were used to reveal risk factors. Neck and shoulder pain, extensor tendonitis of the wrists and De Quervain’s disease were common in the study population. An assessment of risk factors showed that leaning wrists on the keyboard, hard keystrokes, extreme wrist joint and thumb positions and working in poor ergonomic design were correlated to pain and development of CTDs.

2

Relevance of the EMG/Grip Relationship in Isometric Anisotonic Conditions

Claudon L.

International Journal of Occupational Safety and Ergonomics

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2003

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Vol. 9, No. 2

121--134

EN

The aim of the present study was to develop a relationship to evaluate grip force using the electromyogram (EMG) in isometric anisotonic conditions. The EMGs of the flexor digitorum superficialis (FDS) and the extensor digitorum (ED) were recorded in 3 flexion-extension positions of the wrist (30° flexion, 30° extension, and 60° extension) associated with 3 positions of the forearm (70° pronation, prono-supination, and 70° supination). For each position, the participants had to follow linear ramp targets (2 rates of increase and decrease) displayed on an oscilloscope. The results show the best fit is a quadratic type force-EMG relationship. Some aspects such as the rate of force variation and the forearm and wrist positions are then discussed along with the limitations of the relationship.

3

Ergonomic Program Effectiveness: Ergonomic and Medical Intervention

McSweeney K. P., Craig B. N., Congleton J. J., Miller D.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 4

433--449

EN

The implementation of a successful ergonomic and medical intervention program designed to reduce the number and severity of injuries and illnesses and the associated levels of discomfort in the workplace is presented. Because of the recent activity concerning the on-again-off-again Occupational Safety and Health Administration (OSHA) Ergonomic Program Standard questions have been raised as to the value and effectiveness of an organization’s ergonomics program. In light of these concerns, the immense cost associated with work-related injury and illness, and the related pain and suffering associated with such injuries and illnesses, it is important to present a workable and effective ergonomic and medical intervention program. The results of this applied study demonstrate that through the application of an ergonomic and medical intervention program, workplace-related injuries and illnesses can be reduced or eliminated.

4

Evaluation of Grip Force Using Electromyograms in Isometric Isotonic Conditions

Claudon L.

International Journal of Occupational Safety and Ergonomics

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1998

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Vol. 4, No. 2

169--184

EN

The purpose of this study was to develop a relationship to evaluate the grip force (forcerel) using the electromyogram (EMGrel) of the flexor digitorum superficialis (FDS) and of the extensor digitorum (ED) according to the flexion-extension wrist angle (0t-e) and to the pronation-supination forearm angle (0p-s). Fifteen participants had to exert 3 levels of grip forces in 4 positions of the wrist combined with 3 positions of the forearm. The relationship is: forcerel = 0.0045 • 0t-e • EMGrel(FDS) + 0.48 • EMGrel(FDS)-0.0014 • 0t-e • EMGrel(ED) -0 .0016 • 0p-s • EMGrel(ED) • 0.4- EMGrel(ED) This relationship can be used to estimate grip force for levels of strength lower than 50% of the maximal voluntary contraction.

5

Electromyographic Analysis of a Repetitive Hand Gripping Task

Cook T., Rosecrance J., Zimmermann C., Gerleman D., Ludewig P.

International Journal of Occupational Safety and Ergonomics

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1998

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Vol. 4, No. 2

185--198

EN

Electromyography (EMG) has been proposed as a method for determining muscle effort in repetitive upper limb tasks, which are often related to cumulative trauma disorders. EMG activity of the finger flexor musculature was investigated during a repetitive hand gripping task having 5 different cycle durations (2 to 6 s), various percentage of work time (and rest) within the work cycle (20% to 80%), and 3 different grip force levels. Thirty healthy adult participants each performed 27 randomly ordered 30-s repetitive hand gripping trials as well as 3 isometric contractions, which were used to normalize data from the hand gripping trials. There was a significant decrease in mean EMG as the duration of the work-rest cycle time increased. At each force level, EMG increased as the percentage of work time within the work-rest cycle increased, but to a greater extent at the highest force level. The results of this study suggest that overall muscle effort, and perhaps muscle fatigue, can be reduced most effectively by modifying the force requirements of the repetitive task. Other variables, such as the percentage of work time within a cycle and overall work cycle time have less effect on the EMG activity level. The results of this study have implications for developing strategies to reduce muscle fatigue during repetitive hand gripping tasks in an effort to reduce the effects of cumulative trauma disorders.