Effects of the height of ball-backrest on head and shoulder posture and trunk muscle activity in VDT workers

Won Gyu Yoo, Chung Hwi Yi, Sang Hyun Cho, Hye Seon Jeon, Heon Seock Cynn, Houng Sik Choi

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

This study was designed to elucidate the effects of a ball-backrest at different heights on the head and shoulder posture and neck and trunk muscles of visual display terminal (VDT) workers who adopted a forward head posture when working at a VDT. Twenty-three VDT workers with forward head posture performed the keyboard typing work at a VDT without and with a ball-backrest at the L3, T10, and T4 levels. Surface electromyograms were recorded from the neck, shoulder, and trunk muscles, and the forward head angle and forward shoulder angle were analyzed using a 3-D motion analysis system. The significance of differences for the ball-backrest at different heights was tested by repeated one-way ANOVA, with the significance cutoff set at p=0.05. The mean forward head angle and forward shoulder angle decreased in the order of no backrest, T10-level ball-backrest, T4-level ball-backrest. Compared with not using a backrest, the activity of midcervical muscles was significantly lower and that of the lower trapezius was significantly higher when using a T4-level ball-backrest, and the activity of the internal oblique abdominal muscle was significantly higher when using a T10-level ball-backrest. We suggested that using T4 and T10-level ball-backrests would produce similar effects to active exercise, such as ball exercise for trunk stabilization, and that a ball-backrest would prevent kinematics changes. Therefore, the height of the backrest must be determined on the basis of the characteristics of work-related musculoskeletal disorders when applying a ball-backrest to VDT workers with such disorders.

Original languageEnglish
Pages (from-to)289-297
Number of pages9
JournalIndustrial Health
Volume46
Issue number3
DOIs
Publication statusPublished - 2008 May 1

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Posture
Head
Muscles
Neck Muscles
Superficial Back Muscles
Electromyography
Biomechanical Phenomena
Analysis of Variance
Neck
selenium disulfide

All Science Journal Classification (ASJC) codes

  • Public Health, Environmental and Occupational Health
  • Health, Toxicology and Mutagenesis

Cite this

Yoo, Won Gyu ; Yi, Chung Hwi ; Cho, Sang Hyun ; Jeon, Hye Seon ; Cynn, Heon Seock ; Choi, Houng Sik. / Effects of the height of ball-backrest on head and shoulder posture and trunk muscle activity in VDT workers. In: Industrial Health. 2008 ; Vol. 46, No. 3. pp. 289-297.
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Effects of the height of ball-backrest on head and shoulder posture and trunk muscle activity in VDT workers. / Yoo, Won Gyu; Yi, Chung Hwi; Cho, Sang Hyun; Jeon, Hye Seon; Cynn, Heon Seock; Choi, Houng Sik.

In: Industrial Health, Vol. 46, No. 3, 01.05.2008, p. 289-297.

Research output: Contribution to journalArticle

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