Issue 3/4 Vol. 37 1995

Ergonomic methods for the evaluation of physiological cost resulting from manual work

STRASSER, H.

Repetitive manual tasks inherent in supposed light assembly work and in the service industry as well as during use of unhandy working tools are very often the causes of premature fatigue, muscle tension (myogelosis), complaints of the employees, or even occupational diseases. At least physiological cost is unnecessarily increased if properties and characteristics of the human being involved are not considered in movement-based work design as well as in the layout of working tools.

Computer-aided multi-channel electromyographic procedures, which have become more advanced in recent years, meanwhile allow the determination - in figures and numbers - of said physiological cost in terms of local muscle strain resulting from manual work. In the past, the application of electromyography was restricted to the assessment of muscle strain resulting from static workload; nowadays, suitable facilities for the assessment of dynamic muscle work have been developed. The procedures for the evaluation of myoelectric data from time series, for the splitting-up of electromyographic activity, as well as for the quantification of strain level via practice-relevant standardization procedures are described and exemplarily demonstrated. The utilization of multi-channel electromyography, simultaneous recording of work-related energy expenditure, and registration of work pulses revealed bottlenecks of strain and made the priority of the different local and global procedures for the assessment of physical load and strain clear.

For controls and hand tools - for which the human hand should be the measure - the extent of differing physiological cost can be quantified via carefully selected electromyographic registrations. Such quantification reveals that tools which may be aesthetically pleasing but which do not meet ergonomic approval demand a much higher physical investment (input) for an equal or even lesser performance (output).

Keywords: manual task, working tool, muscle tension, electromyography

Short Title: Strasser, H. (1995) PsyBeit 3-4:622

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