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Katharyn A. Grant

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Publications by Katharyn A. Grant (bibliography)

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1994
 
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Grant, Katharyn A. (1994): Evaluation of Grip Force Exertions in Dynamic Manual Work. In: Proceedings of the Human Factors and Ergonomics Society 38th Annual Meeting 1994. pp. 549-553.

An obstacle to the development of guidelines for reducing forceful hand movements is that manual force is not easily measured or estimated at the worksite, especially during highly dynamic activities. Grip force requirements during manual work are dependent not only on object weight, but also on the surface characteristics of the object and the task dynamics. In theory, it is possible to predict grip force requirements for manual tasks using Newtonian laws of physics; however few researchers have attempted to measure grip force during dynamic work, much less to compare actual grip force values to predicted levels. Therefore, a laboratory experiment was conducted to examine grip force exertions during two simulated industrial tasks. In each task, participants repetitively grasped and moved aluminum handles against varying levels of weight or resistance. Grip force was measured using a strain gauge mounted inside the handles. Results indicate that grip force varied continuously throughout each work cycle in response to changes in the motion of the hand/handle. The pattern of variation was consistent between subjects and could be approximated by a sinusoidal model. Greater interindividual variation in grip force exertion was observed when the task allowed greater flexibility in selecting a movement strategy. The results also indicate that subjects are more likely to "overshoot" the necessary grip force (i.e., apply more force than needed) at the initiation of movement, especially at lower weight levels. This study demonstrates that it is possible to predict variations in grip force during dynamic work, although further refinements in the procedure are needed. Use of modelling techniques will enable industrial designers to better estimate grip force requirements and to identify design strategies that will reduce the risk of musculoskeletal injury to the worker.

© All rights reserved Grant and/or Human Factors Society

1993
 
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Grant, Katharyn A., Galinsky, Traci L. and Johnson, Peter W. (1993): Use of the Actigraph for Objective Quantification of Hand/Wrist Activity in Repetitive Work. In: Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993. pp. 720-724.

Valid and reliable measures of hand/wrist activity are needed to address the relationship between work tasks and the development of upper extremity musculoskeletal disorders. The utility of the actigraph for measuring wrist activity in manual work was examined in this study. Ten grocery cashiers and four non-cashier retail workers wore actigraph monitors on both wrists and the left ankle during their normal work activities. Work activities were periodically observed and recorded on videotape. Data recorded by the actigraphs were matched against observational data. The results indicated that actigraphy was effective in detecting significant work-related variations in physical activity in the three limbs studied. Compared to traditional observational procedures, actigraphy represents a cost-effective approach for obtaining objective and quantitative information about the intensity and duration of work over long time periods. Traditional observational procedures, however, are necessary to provide additional information needed for a complete job analysis (e.g., postural data). Continuous activity recordings can be used in conjunction with sampling protocols to examine the relationship between work-related physical activities and musculoskeletal trauma.

© All rights reserved Grant et al. and/or Human Factors Society

 
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Changes to this page (author)

21 Feb 2010: Modified
26 Jun 2007: Added
26 Jun 2007: Added

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May 25

Civilization advances by extending the number of important operations which we can perform without thinking of them.

-- Alfred North Whitehead

 
 

Featured chapter

Read the fascinating history of Wearable Computing, told by its father, Steve Mann

Read Steve's chapter !

 
 

Help us help you!