7

Work Capacity, Stress and Fatigue

The term (fatigue) should be absolutely banned from scientific discussion. Is a fatigue test possible? (B. Muscio (1921) British Journal of Psychology, 12:31-46)

Stress and fatigue are words used in a variety of ways by ergonomists. Sometimes they are used to refer to temporary states of parts of the body. At other times, they are used to refer to chronic states of the whole person. In both senses, stress, arising out of work demands, causes fatigue when work capacity is exceeded.


Stress and fatigue

Stress

Stress is often thought of in a negative way in everyday life. In technical discussion, however, it is perhaps more appropriately viewed as 'applied load' or 'task demand'. The classical physical model of stress is based on Hooke's law: if we place a load of 30 kg on horizontal beam and the beam bends under the load, the stress is 30 kg and the strain is the deformation of the beam. Once the stress is removed, the beam will resume its former shape. Under high loads, the elastic limit of the beam will be exceeded and the beam will not resume its original shape when the stress is removed. Permanent damage results because the stress exceeds the load-bearing capacity.

The classical physiological model of stress is derived from the work of H. Selye espoused in his book The Stress of Life (Selye, 1956). Selye was interested in the endocrinological responses to life events and his key insight was that many, very different, noxious stimuli produce the same effects. This lead Selye to coin the term 'general adaptation syndrome' - a three-phase response to stress consisting of an alarm reaction when the threat is perceived, then resistance, followed by adaptation and finally exhaustion or death. To this day, researchers continue to use endocrine markers such as urinary catecholamine concentration and salivary cortisol levels to assess the overall level of work or life stress. It is believed that the former indicates the level of stress and resulting physiological arousal, whereas the latter indicates the degree of emotional response to the situation in which the stress is experienced (Lundberg, 1995). Salivary cortisol levels, taken early in the morning are used to assess recovery from stress - higher levels indicate delayed recovery, from which higher levels of work stress are inferred. Sluiter et al. (2000), for example, found raised levels of cortisol and adrenaline in workers with jobs that combined mental

-187-

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 ...
Project items

Items saved from this book

This book has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this book

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

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 page

Bookmark this page
Introduction to Ergonomics
Settings

Settings

Typeface
Text size Smaller Larger
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?

Full screen
/ 553

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, 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."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

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

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.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.