6

Design of manual handling tasks

Low Back Pain remains the most prevalent and costly work-related injury.

(Liberty Mutual Research Center Research Report, 1998)

A large proportion of the accidents that occur in industry involve the manual handling of goods. In the USA, about 500 000 workers, suffer some type of overexertion injury per year. Approximately 60% of the overexertion injury claims involve lifting and 20% pushing or pulling (NIOSH, 1981). In the UK, more than 25% of accidents involve handling goods in one way or another (Health and Safety Commission, 1991). A 10% reduction in manual handling injuries would save the British economy some £170 million per annum.

The relation between low-back injury and workplace ergonomics is supported by the findings of epidemiological surveys. Hoogendoorn et al. (2000) found an increased risk of low back pain in workers who lifted a 25 kg load more than 15 times per day. Magora (1972) found that low back symptoms were more common in workers who regularly lifted weights of 3 kg or more than in those who sometimes lifted such weights. Interestingly, low back symptoms were even more common in those who rarely lifted weights.


Anatomy and biomechanics of manual handling

When carrying out manual handling tasks, the weight of the load being lifted is transferred to the spinal column in the form of compression and shear forces. The compression and shear are greater when the load is lifted quickly because higher forces are needed to accelerate the mass from rest, according to Newton's laws of motion.

Thus, larger forces are required to lift an object quickly, rather than slowly, and these are transferred to the spine. Additional loads are placed on the spine owing to posture - the more 'off-balance' or assymmetric the posture, the greater the muscle forces needed to counteract the pull of gravity. Combining accelerations of the trunk and the load with asymmetric postures introduces a requirement for high antagonistic contractions in the muscle groups around the trunk: one set of muscles acts to accelerate the load and another to maintain the integrity of the spinal column and control the acceleration and deceleration of the trunk itself. The result of all this contraction and co-contraction is increased compression and shear on the vertebral motion segments (see Granata and Marras, 2000).

-158-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Note: primary sources have slightly different requirements for citation. Please see these guidelines for more information.

Cited page

Bookmark this page
Introduction to Ergonomics
Table of contents

Table of contents

Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Help
Full screen
Items saved from this book
  • Bookmarks
  • Highlights & Notes
  • Citations
/ 553

matching results for page

    Questia reader help

    How to highlight and cite specific passages

    1. Click or tap the first word you want to select.
    2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
    3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

    OK, got it!

    Cited passage

    Style
    Citations are available only to our active members.
    Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

    1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

    Cited passage

    Thanks for trying Questia!

    Please continue trying out our research tools, but please note, full functionality is available only to our active members.

    Your work will be lost once you leave this Web page.

    Buy instant access to save your work.

    Already a member? Log in now.

    Search by... Author
    Show... All Results Primary Sources Peer-reviewed

    Oops!

    An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.