The Effect of Jar Holding Posture on Finger Force and Torque during a Jar-Opening Task for Young Females

Many young females have difficulty opening jars. Although previous studies have attempted to clarify the body posture effect during such a task, the experiments therein focused on a single digit or actions with unnatural finger positions and were further restricted to upper extremity postures. A fur...

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Veröffentlicht in:Packaging technology & science Jg. 27; H. 4; S. 265 - 276
Hauptverfasser: Huang, C.-Y., Kuo, L.-C., Tseng, H.-Y., Su, F.-C.
Format: Journal Article
Sprache:Englisch
Veröffentlicht: Bognor Regis Blackwell Publishing Ltd 01.04.2014
Wiley Subscription Services, Inc
Schlagworte:
coordinate model
Digits
Females
Fingers
jar opening
Mathematical analysis
posture effect
simulated jar device
Simulation
Strategy
Tasks
Torque
ISSN:0894-3214, 1099-1522
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Zusammenfassung:Many young females have difficulty opening jars. Although previous studies have attempted to clarify the body posture effect during such a task, the experiments therein focused on a single digit or actions with unnatural finger positions and were further restricted to upper extremity postures. A further study is required to investigate the fingers’ coordination, as well as each subject's natural and self‐selected upper extremity posture and finger grasp location when opening a jar. This study focused on the forces and coordination of the right hand fingers during a jar opening movement under both vertical and free‐way opening postures. A jar simulator was set up to record the forces applied by finger groups (the thumb, the index–middle finger group, and the ring–little finger group) of the right hand. A self‐selected finger position and free‐arm posture of each subject were allowed. Results show that the force vectors of the finger groups were all in the counterclockwise direction for both postures. The total force and overall torque of the right hand decreased in the vertical opening posture. The thumb produced greater tangential and resultant forces in the vertical opening posture. Despite normal forces being 1.82–3.54 times the tangential forces for both postures, no difference was found for the normal force to tangential force ratio for each finger group between the two opening postures. The index–middle finger group had similar torque contributions for both postures. The torque contribution of the thumb increased (26% and 21% for vertical and free‐way posture, respectively), while the ring–little finger group torque contribution decreased (35% and 42% for vertical and free‐way posture, respectively) in the vertical opening posture. As such, the free‐way opening posture is the better strategy for young females to open a jar. Copyright © 2013 John Wiley & Sons, Ltd. This study used a jar simulator to investigate the posture effect on finger group behaviours for young females during opening a jar. The results of this study showed that the free‐way opening posture is a better strategy for young females to adopt in the jar opening task when standing. The details of the four fingers must be clarified, and the performance of different grasp patterns in future studies could provide more evidence in this area of interest.
Bibliographie:istex:6DCCD89FCF64571860B97A13B9F93CB40619987D
ark:/67375/WNG-C860G2Q7-F
ArticleID:PTS2031
ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 14
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ISSN:0894-3214
1099-1522
DOI:10.1002/pts.2031