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1

Evaluation of pliers’ grip spans in the maximum gripping task and sub-maximum cutting task

Kim D.-M., Kong Y. K.

International Journal of Occupational Safety and Ergonomics

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2016

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Vol. 22, No. 4

449--456

EN

A total of 25 males participated to investigate the effects of the grip spans of pliers on the total grip force, individual finger forces and muscle activities in the maximum gripping task and wire-cutting tasks. In the maximum gripping task, results showed that the 50-mm grip span had significantly higher total grip strength than the other grip spans. In the cutting task, the 50-mm grip span also showed significantly higher grip strength than the 65-mm and 80-mm grip spans, whereas the muscle activities showed a higher value at 80-mm grip span. The ratios of cutting force to maximum grip strength were also investigated. Ratios of 30.3%, 31.3% and 41.3% were obtained by grip spans of 50-mm, 65-mm, and 80-mm, respectively. Thus, the 50-mm grip span for pliers might be recommended to provide maximum exertion in gripping tasks, as well as lower maximum-cutting force ratios in the cutting tasks.

2

Optimization of the levels of grip force, stroke rotation, frequency and grip span for a torqueing task

Bano F., Mallick Z., Khan A. A.

International Journal of Occupational Safety and Ergonomics

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2015

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Vol. 21, No. 1

94--104

EN

This study was to investigate the effects of grip force, frequency, stroke rotation and grip-span on discomfort and obtain best posture for hand tool users. Fifteen male participants volunteered in this study. Participants performed combined gripping with torqueing exertions for 5 min for two levels of frequency (10 and 20 exertions/min) at two levels of grip force (50 and 70 N), two levels of stroke rotation (30° and 60°) and three levels of grip-span (4.7, 6 and 7.3 cm). Therefore, a 2×2×2×3 full factorial design was used. The analysis of variance (ANOVA) showed that frequency, stroke rotation and grip-span were significant on discomfort score. Minimum discomfort and comfortable posture was found to be 90 N grip force with 10 exertions/min for 60° stroke rotation at 6-cm grip-span. The grip force, frequency and stroke rotation were found significant on EMG activity of forearm muscles using multivariate analysis of variance (MANOVA). The extensor muscles were found more activated than flexor muscles during the given task.

3

A new simple local muscle recovery model and its theoretical and experimental validation

Ma L., Zhang W., Wu S., Zhang Z.

International Journal of Occupational Safety and Ergonomics

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2015

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Vol. 21, No. 1

86--93

EN

This study was conducted to provide theoretical and experimental validation of a local muscle recovery model. Muscle recovery has been modeled in different empirical and theoretical approaches to determine work-rest allowance for musculoskeletal disorder (MSD) prevention. However, time-related parameters and individual attributes have not been sufficiently considered in conventional approaches. A new muscle recovery model was proposed by integrating time-related task parameters and individual attributes. Theoretically, this muscle recovery model was compared to other theoretical models mathematically. Experimentally, a total of 20 subjects participated in the experimental validation. Hand grip force recovery and shoulder joint strength recovery were measured after a fatiguing operation. The recovery profile was fitted by using the recovery model, and individual recovery rates were calculated as well after fitting. Good fitting values (r2 > .8) were found for all the subjects. Significant differences in recovery rates were found among different muscle groups (p < .05). The theoretical muscle recovery model was primarily validated by characterization of the recovery process after fatiguing operation. The determined recovery rate may be useful to represent individual recovery attribute.

4

Isometric Pull-Push Strengths in Workspace. 2, Analysis of Spatial Factors

Das B., Wang Y.

International Journal of Occupational Safety and Ergonomics

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2004

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Vol. 10, No. 1

59--64

EN

The effect of reach levels, horizontal angles and vertical angles on isometric pull and push strengths of males and females in standing and seated positions was determined. The effect of reach levels on strength varied as a consequence of force direction, working position and gender. Reach level has a significant effect on women's pull strength in the seated position and on push strength in the standing position. The strength value was significantly greater in the extreme reach than in maximum or normal reach. Vertical angle ö had a significant effect on strength consistently in all cases. Strength values increased significantly with the increase of ö angles from 0º to 45º to 90º. The horizontal angle è had a significant influence only on the pull strength of standing and seated men and standing women (not seated woman). The maximum strength was significantly greater at è = 90º.

5

Isometric Pull-Push Strengths in Workspace. 1, Strength Profiles

Das B., Wang Y.

International Journal of Occupational Safety and Ergonomics

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2004

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Vol. 10, No. 1

43--58

EN

The isometric pull and push strength profiles of males and females were determined in seated and standing positions in the workspace. The strongest pull strength location was at extreme reach vertically above the shoulder for both males and females. The greatest pull strength of 400 Newtons (N) for males was recorded in the seated and standing positions. Females. pull strengths in the seated and standing positions were 222 and 244 N, respectively. The strongest push strength was always at the maximum reach at the overhead location. Males. maximum push strength was 227 N in the seated position and 251 N in the standing position. Females’ maximum push strength was 96 N in the seated position and 140 N in the standing position. On the average the strength in the standing position was 79% of the seated position. The push strength was 71% of the pull strength and females were 56% as strong as males.

6

Reasons for Applying Innovations for Scaffolding Work

Jong A. M., Molen H. v. d., Vink P., Eikhout S., Koningsveld E.

International Journal of Occupational Safety and Ergonomics

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2003

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Vol. 9, No. 2

161--175

EN

In this paper reasons for applying and for not applying technical and organizational innovations in scaffolding work are studied. In a participatory ergonomic approach these innovations were developed to reduce problems concerning physical load of scaffolders. In this study reasons for the adoption of the innovations in the scaffolding sector are evaluated in 2 studies, in 48 companies. More than half of the scaffolding sector in the Netherlands adopted the innovations. Reasons for applying innovations concerned improvement of work and health and satisfaction with usage. The reason for not applying the innovations concerned specific situations, such as offshore work, in which innovations were not applicable.

7

Three-Dimensional Lifting Model For Non-Homogeneous Loads

Gilad I., Boughanim D.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 4

511--524

EN

A 3-dimensional model and analysis methodology is suggested for treating lifting tasks when unbalanced loads are involved. The paper describes the biomechanical equations that are coupled with the worker’s posture geometry, to address a practical problem of non-symmetric lifting. The analysis has a dominant biomechanical modeling scope, as it contains a breakdown of the internal lifting forces resulting from posture and external loads acting on the body. The load model represents the acting forces due to unbalanced lifting, which is commonly found in industrial situations. The suggested model allows the user to simulate the influence of the practical load distribution, aiding safe design of a lifting job.

8

Interaction of Physical and Mental Work

Singh S., Aghazadeh F., Ray T. G.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 4

451--463

EN

The objective of the research was to determine the effect of mental load on the physical capacity of an individual. An experiment involving 9 combinations of lifting tasks, 1 lowering task, and 3 treadmill tasks was conducted. Heart rate was measured and maximum acceptable weight of lift was determined using the psychophysical method. A simple multiplication task was used as the mental load. The output variables were determined with and without the mental task. The results indicate that the individual’s physical capacity decreased with the mental task while lifting from floor to knuckle and shoulder to reach lifting heights.

9

Assessment of the Musculoskeletal Load of the Trapezius and Deltoid Muscles During Hand Activity

Roman-Liu D., Tokarski T., Kamińska J.

International Journal of Occupational Safety and Ergonomics

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2001

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Vol. 7, No. 2

179--193

EN

The purpose of the study was to analyse the influence of the precision of a task on tension and fatigue of the trapezius and deltoid muscles. Ten young men took part in experiments. Different levels of force and different frequencies of pressing a button defined the precision of the task. Surface electromyography (EMG) was used. Muscle tension and fatigue were reflected by 2 parameters of the EMG signal: the Root Mean Square amplitude related to the maximum value and changes in the Median Power Frequency. The results showed that hand activities influence the descending part of the trapezius muscle and do not influence the deltoid muscle, and that the precision of work can influence the examined muscles of the arm and shoulder even during work in which only the hand is involved in a performed task.

10

A Prescriptive Exercise Program for Health Maintenance

Yamashita A., Kawakami M., Inagaki Y., Ohkubo T.

International Journal of Occupational Safety and Ergonomics

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2001

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Vol. 7, No. 2

195--209

EN

The aim of this study was to design a prescriptive exercise program for people of various age and fitness basing on the popular in Japan Radio Physical Fitness Exercise, a program based on an experimental approach. The evaluation indices used in the experiment were heart rate (HR), oxygen consumption, and electrical activity of the rectus femoris, latissimus dorsi, and trapezius muscles, which measured during various motion elements of the program performed at various rate. The results of this study enable to calculate equations for predicting HR during exercise from relative metabolic rate (RMR). The data on HR, RMR, and myoelectric potential presented in this study may be a basis for designing individual exercise programs for elderly people.

11

Isometric Pull and Push Strengths of Paraplegics in the Workspace: 2. Statistical Analysis of Spatial Factors

Das B., Black N. L.

International Journal of Occupational Safety and Ergonomics

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2000

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Vol. 6, No. 1

67-80

EN

The effect of reach levels, horizontal angles, and vertical angles on isometric pull and push strengths of male and female was determined. Highly significant increases in men’s push strength were found between extreme to maximum reaches, and from extreme to normal reaches. However, for women’s push strength, a significant increase was found only between extreme to maximum reach. Significant or highly significant increases were found in men’s and women’s pull strength between the horizontal angle (0) sagittal through the active shoulder (90°) and other angles (0, 45, and 135°). However, for men’s push strength, highly significant increases were found between the horizontal angle 45° from the frontal plane, and other angles. For women’s push strength, significant or highly significant increases were found between the horizontal angles 0° and angles of 90 and 135°. For men’s and women’s pull strength, significant or highly significant increases were found between the vertical angle (), 90°, and other angles (-20, 0, and 45°). Similar increases were found for women’s push strength between the 45° angle and other angles. In the design of a workstation for paraplegics that requires pull and push forces, consideration must be given to the spatial factors.

12

Isometric Pull and Push Strengths of Paraplegics in the Workspace: 1. Strength Measurement Profiles

Das B., Black N. L.

International Journal of Occupational Safety and Ergonomics

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2000

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Vol. 6, No. 1

47--65

EN

The isometric strength profiles of male and female paraplegics were determined for pull and push strengths in the normal, maximum, and extreme working reach envelopes. A computerized isometric strength measurement system was designed and constructed for the purpose. The strongest pull location was at extreme reach vertically above the shoulder and the strength values for males and females were 473 and 318 newtons (N), respectively. The strongest push location was at maximum reach, at vertical ($) angle of 45° and at horizontal (6) angle of 45° for males and at 0° for women and the strength values were 235 and 172 N, respectively. The nature of the strength profiles was found to be similar for both the sexes. The pull and push strengths of the female were 77 and 68% that of the male, respectively.