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Ergonomics. 2011 Jan;54(1):47-59. doi: 10.1080/00140139.2010.535021.

A study of the difference between nominal and actual hand forces in two-handed sagittal plane whole-body exertions.

Author information

1
University of Michigan Transportation Research Institute, Ann Arbor, MI, USA. grovess@umich.edu

Abstract

Given a task posture, changes in hand force magnitude and direction with regard to joint locations result in variations in joint loads. Previous work has quantified considerable vertical force components during push/pull exertions. The objective of this work was to quantify and statistically model actual hand forces in two-hand, standing exertions relative to the required nominal horizontal and vertical hand forces for a population of widely varying stature and strength. A total of 19 participants exerted force on a fixed handle while receiving visual feedback on the magnitude of force exerted in the required horizontal or vertical direction. A set of regression equations with adjusted R(2) values ranging from 0.20 to 0.66 were developed to define actual hand force vectors by predicting off-axis forces from the required hand force magnitude. Off-axis forces significantly increase the overall magnitude of force exerted in two-hand push/pull and up/down standing force exertions.

STATEMENT OF RELEVANCE:

This study quantifies and statistically models actual hand forces in two-hand, standing exertions. Inaccuracies in hand force estimates affect the ability to accurately assess task-oriented strength capability. Knowledge of the relationship between nominal and actual hand forces can be used to improve existing ergonomic analysis tools, including biomechanical simulations of manual tasks.

PMID:
21181588
DOI:
10.1080/00140139.2010.535021
[Indexed for MEDLINE]

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