The Effects of Direction on the Maximal Grip, Pusing, Pulling, and Twisting Forces

다국어 초록 (Multilingual Abstract)

Objective: The aims of this study were to understand the effects of task direction on the output (pushing, pulling, and clockwise and counter clockwise twisting) and the maximal grip forces and to explore the relationship between the grip and the output forces.
Background: Thoughtful handle design improves the productivity and prevents the work-related musculoskeletal disorders.
Method: Eighteen healthy volunteers without any history of neuromuscular disorders were recruited. A custom-made handle and a load cell measured the grip force and the output for three seconds. Force measurements along the vertical, coronal and sagittal axes were randomly repeated three times and averaged. The data were analyzed using the repeated measures ANOVA for the effects of task direction on the output and the maximal grip forces and simple linear regression for the relationship between the grip and the output forces.
Results: There was no significant effect of direction on the output and grip forces. The pulling force was greatest and the pushing force was smallest in all directions. The order of grip force was pushing, pulling, clockwise twisting, and counter clockwise twisting in all directions. The output and grip forces were highly correlated in all directions. The regression coefficient of grip force was greatest in pulling and smallest in clockwise twisting.
Conclusion: Findings of this study suggests that a smart handle design can improve the productivity more in pushing and pulling than twisting tools. Application: It can be valuable information for product designers to develop more productive hand tools and to prevent the musculoskeletal disorders in the upper extremities.

목차 (Table of Contents)

• ABSTRACT
• 1. Introduction
• 2. Method
• 3. Results
• 4. Conclusion
• References