Title:
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Measurement and modelling of postural work load.
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This study was concerned with the measurement and
modelling of postural work load and recovery. Five
stationary stooped postures were examined and the data
derived therefrom were used in the development of some
predictive mathematical models of postural work recovery.
The models were found to fit the data very well and, when
tested in two different situations, were found to be about
70% reliable, at the worst. The models tend to refute the
view that a knowledge of the forces being exerted by the
various muscles is necessary before postural work recovery
can be predicted. The models showed, at least for the five
postures studied, the duration of work was the primary
factor influencing recovery, rather than rest. Rest pauses
of about 1200% of work were used for some of the subjects,
despite which full and complete recovery was not achieved.
The models lend support, albeit obliquely, to some studies
at ~he micro-level involving muscle-biopsies, performed to
elucidate the possible mechanisms which underlie the fatigue
and recovery processes.
In keeping with the multi-disciplinary nature of
ergonomics, this study has taken an eclectic course, drawing
upon the theories and methods of such areas as statistics and
communication engineering to produce two new techniques for
the analysis of subjective assessment data. These-two
techniques make subjective assessment data more amenable to
quantitative analysis, thereby affording some precision in
the handling of data which are susceptible to personalistic
or idiosyncratic influences. Bayes Theorem and Shannon's
Information Theory have been the basis of these two techniques.
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