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Disabling back pain among nurses and other occupations in Wisconsin
382
Abstracts
was significantly affected by the weight, reach and level of lifts (p < 0.05) but not by the plane of activity. A high multiple correlation between the metabolic cost and task variables were obtained (multiple R = 0.86. p < 0.00001). A highly significant metabolic cost predictive model was developed. AN EXPERIMENTAL
EVALUATIOS
OF METHOD USE
AND TOOL
EFFECTS
IN SPIKE
iMAUL
W. S. MARRASand T. H. ROCKWELL(Department of Industrial and Systems Engineering, The Ohio State University, Columbus, OH 43210, U.S.A.) An experiment was performed to study the effects of hand tool design factors and methods of tool use upon tool force generation and loading of the back. Methods of use differed according to hand position and motion characteristics of the body. Tool factors considered include tool weight and striking surface area. Forty novice and experienced subjects were tested in their ability to drive an instrumented spike with a railroad spike maul while the back muscle activity was monitored. Method of tool use affected the spike driving performance of novice subjects whereas tool striking surface area influenced the ability of experienced trackmen to drive spikes. Method of tool use also affected the components of spine loading. Tool force generation was also considered as a function of the spine loading indices to create efficiency measures. These efficiency measures were used to evaluate the cumulative trauma effects of the hand tool ELECTROMYOCRAPHIC
PAlTERNS
ASSOCIATED
WITH CARPET
INSTALLATION
TASK
A. BHA?TACHARYA and H. K. RAMAKRISHNAN(Biomechanics-Ergonomics Research Laboratory, Department of Environmental Health, University of Cincinnati Medical Center, Cincinnati, OH, U.S.A.) and D. HABES(National Institute for Occupational Safety & Health, Cincinnati, OH, U.S.A.) The present study was designed to determine (1) the electromyographic (EMG) activity patterns associated with typical static and dynamic postures of carpet installation task and (2) the maximum muscle strength data of relevant muscle groups. Eight male subjects participated in the study who were asked to simulate four static body postures most commonly associated with the carpet installation task. In addition to these postures, subjects were also required to perform the act of carpet stretching using a knee kicker at our specially developed carpet installation simulation facility. For the static postures, the EMG results were different for diiferent muscle groups. For the dynamic task, the EMG activity of the four muscle groups were present only for a portion of the kicking cycle. On the average, for the eight subjects, these values were: quadriceps, 35 ?A;deltoid (before impact), 23 “,A;deltoid (after impact), 30 %; and hamstrings (before impact), 3 1“lo. TECHNIQUES
FOR FUNCTIONAL
ASSESSMENT IN THE WORKPLACE OF LOW BACK PAIN
TO REDUCE
RISK
S. REINECKE,B. BEYNNON,G. WEISMANand M. POPE (The University of Vermont, U.S.A.) Eight jobsite visits have been undertaken as a preliminary step toward developing a methodology for worksite evaluation from a human factors perspective. Worksite assessment includes investigation of both the workers’ functional physical capabilities and job task requirements. By refining measurement techniques, it is hoped that low back pain and injury can be significantly reduced in the workplace by matching workers and jobs and by modification of current task requirements. The present study focuses on the design of instrumentation for measuring range of motion in work-related settings and the assessment of postural variables in a seated, static environment. Preliminary seating results suggest that, in a static environment, sitting tolerance is longest for an erect, upright posture and is limited by postures combining various degrees of forward flexion, lateral bending and rotation. DISABLING
BACK PAIN AiMONG NURSES AND OTHER
OCCUPATIONS
ROGER C. JENSEN (Division of Safety Research, National Institute for Occupational U.S.A.)
IN WISCONSIN Safety and Health,
Hospitalized patients must occasionally be lifted and moved by nurses and nurses’ aides using postures which create latge compressive and torsional forces on their lower back. One would therefore expect from theories of
183
Abstracts
occupational biomechanics that patient handling occupations would have large incidence rates of back pain disorders. This paper describes an assessment of Wisconsin workers’ compensation data tending to confirm this expectation. Twenty-five occupational groups selected to provide interesting comparisons were rank ordered from the largest to smallest incidence ratio. Results show nursing aides ranked first, followed in order by construction laborers, garbage collectors, licensed practical nurses, truck drivers, machinists, registered nurses, and health aides. Additional analyses of this data indicate that the relativ,ely high incidence ratios of the nursing occupations are not explained by gender or ease of access to medical care.
A CO.MPUTER-AIDED
W. MONROE
KEYSERLING
SYSTEM FOR MEASURING BIOMECHANICAL STRESSES ON INDUSTRIAL JOBS
AND POSTURAL
and DOX B. CHAFFIN (Center for Ergonomics, The University of Michigan, Ann Arbor, MI 48103, U.S.A.)
Manual work in industry can place workers in awkward postures that may cause fatigue and musculoskeletal disorders of the back and shoulders. If the worker is required to exert significant forces while maintaining an awkward posture, the potential for injury or fatigue increases. As part of a factory-based epidemiological study of occupational back and shoulder disorders, it was necessary to develop an efficient, non-invasive system to measure posture and biomechanical stress. This system utilized a videotape to initially document the jobs, and a personal computer to record, reduce, and report postural and biomechanical results. The findings of this study will provide a better understanding of the prevalence and causes of injuries to the back and shoulders in industry.
INTEGRATED
ERGONOiMIC
OPERATOR-EQUIP.VENT
MODELS
KARL H. E. KROEMER(Ergonomics Laboratory, Department of Industrial Engineering and Operations Research, Virginia Tech University, Blacksburg, VA 21061, U.S.A.) Computerized models of human anthropometry and biomechanics are being used in research and teaching as well as for the design of manned systems in industry, military and space systems. A basic problem is that different universities, laboratories and industries use various models which have varying input requirements, disparate structures and data bases, and incompatible outputs. Although anthropometric, biomechanical and interface data are all necessary to the systematic equipment design process, they have never been integrated into a comprehensive ergonomic model of the human operator. Hence, there is incomplete understanding of the human as a system component. Development of an integrated ergonomic model of the human operator requires an overall conceptual framework to guide construction of the overall model itself as well as to guide systematic, interrelated research on its constituent parts. The Committee on Human Factors of the National Research Council conducted a two day workshop on 17 and 18 June 1985 to assess feasibility and requirements necessary to develop an integrated ergonomic model. This presentation reports on the points of view presented at the workshop. on the ensuing discussions. and on the results obtained.
REACH ANALYSIS USING THOMAS
DRAWING
BOARD
~MANIKINS ASD A MICRO-COMPUTER
J. ARMSTRONG and ROBERT G. RADWIN (The University of Michigan, U.S.A.) and Force Aero Medical Research Laboratory, U.S.A.)
KENNETH W. KENNEDY (Air
The availability of micro-computer equipment and CAD software makes it possible to evaluate anthropometric work requirements on a routine basis. The human body is depicted using stick figures that are constructed using CAD ‘line’ commands. The body also is depicted using two dimensional drawing board templates. Each segment is digitized and stored in file. A menu is created so that the files can be easily retrieved and the segments scaled and oriented at desired locations on work station drawings. ‘Arc’commands are used to construct reach envelopes to determine if controls, tools and materials can be reached without excessive postural stress. Additional research is required to validate predicted reach limits with empirical data, determine the limits ofa two-dimensional analysis, generate simplified templates and develop software to facilitate connecting the body links.
Abstracts
was significantly affected by the weight, reach and level of lifts (p < 0.05) but not by the plane of activity. A high multiple correlation between the metabolic cost and task variables were obtained (multiple R = 0.86. p < 0.00001). A highly significant metabolic cost predictive model was developed. AN EXPERIMENTAL
EVALUATIOS
OF METHOD USE
AND TOOL
EFFECTS
IN SPIKE
iMAUL
W. S. MARRASand T. H. ROCKWELL(Department of Industrial and Systems Engineering, The Ohio State University, Columbus, OH 43210, U.S.A.) An experiment was performed to study the effects of hand tool design factors and methods of tool use upon tool force generation and loading of the back. Methods of use differed according to hand position and motion characteristics of the body. Tool factors considered include tool weight and striking surface area. Forty novice and experienced subjects were tested in their ability to drive an instrumented spike with a railroad spike maul while the back muscle activity was monitored. Method of tool use affected the spike driving performance of novice subjects whereas tool striking surface area influenced the ability of experienced trackmen to drive spikes. Method of tool use also affected the components of spine loading. Tool force generation was also considered as a function of the spine loading indices to create efficiency measures. These efficiency measures were used to evaluate the cumulative trauma effects of the hand tool ELECTROMYOCRAPHIC
PAlTERNS
ASSOCIATED
WITH CARPET
INSTALLATION
TASK
A. BHA?TACHARYA and H. K. RAMAKRISHNAN(Biomechanics-Ergonomics Research Laboratory, Department of Environmental Health, University of Cincinnati Medical Center, Cincinnati, OH, U.S.A.) and D. HABES(National Institute for Occupational Safety & Health, Cincinnati, OH, U.S.A.) The present study was designed to determine (1) the electromyographic (EMG) activity patterns associated with typical static and dynamic postures of carpet installation task and (2) the maximum muscle strength data of relevant muscle groups. Eight male subjects participated in the study who were asked to simulate four static body postures most commonly associated with the carpet installation task. In addition to these postures, subjects were also required to perform the act of carpet stretching using a knee kicker at our specially developed carpet installation simulation facility. For the static postures, the EMG results were different for diiferent muscle groups. For the dynamic task, the EMG activity of the four muscle groups were present only for a portion of the kicking cycle. On the average, for the eight subjects, these values were: quadriceps, 35 ?A;deltoid (before impact), 23 “,A;deltoid (after impact), 30 %; and hamstrings (before impact), 3 1“lo. TECHNIQUES
FOR FUNCTIONAL
ASSESSMENT IN THE WORKPLACE OF LOW BACK PAIN
TO REDUCE
RISK
S. REINECKE,B. BEYNNON,G. WEISMANand M. POPE (The University of Vermont, U.S.A.) Eight jobsite visits have been undertaken as a preliminary step toward developing a methodology for worksite evaluation from a human factors perspective. Worksite assessment includes investigation of both the workers’ functional physical capabilities and job task requirements. By refining measurement techniques, it is hoped that low back pain and injury can be significantly reduced in the workplace by matching workers and jobs and by modification of current task requirements. The present study focuses on the design of instrumentation for measuring range of motion in work-related settings and the assessment of postural variables in a seated, static environment. Preliminary seating results suggest that, in a static environment, sitting tolerance is longest for an erect, upright posture and is limited by postures combining various degrees of forward flexion, lateral bending and rotation. DISABLING
BACK PAIN AiMONG NURSES AND OTHER
OCCUPATIONS
ROGER C. JENSEN (Division of Safety Research, National Institute for Occupational U.S.A.)
IN WISCONSIN Safety and Health,
Hospitalized patients must occasionally be lifted and moved by nurses and nurses’ aides using postures which create latge compressive and torsional forces on their lower back. One would therefore expect from theories of
183
Abstracts
occupational biomechanics that patient handling occupations would have large incidence rates of back pain disorders. This paper describes an assessment of Wisconsin workers’ compensation data tending to confirm this expectation. Twenty-five occupational groups selected to provide interesting comparisons were rank ordered from the largest to smallest incidence ratio. Results show nursing aides ranked first, followed in order by construction laborers, garbage collectors, licensed practical nurses, truck drivers, machinists, registered nurses, and health aides. Additional analyses of this data indicate that the relativ,ely high incidence ratios of the nursing occupations are not explained by gender or ease of access to medical care.
A CO.MPUTER-AIDED
W. MONROE
KEYSERLING
SYSTEM FOR MEASURING BIOMECHANICAL STRESSES ON INDUSTRIAL JOBS
AND POSTURAL
and DOX B. CHAFFIN (Center for Ergonomics, The University of Michigan, Ann Arbor, MI 48103, U.S.A.)
Manual work in industry can place workers in awkward postures that may cause fatigue and musculoskeletal disorders of the back and shoulders. If the worker is required to exert significant forces while maintaining an awkward posture, the potential for injury or fatigue increases. As part of a factory-based epidemiological study of occupational back and shoulder disorders, it was necessary to develop an efficient, non-invasive system to measure posture and biomechanical stress. This system utilized a videotape to initially document the jobs, and a personal computer to record, reduce, and report postural and biomechanical results. The findings of this study will provide a better understanding of the prevalence and causes of injuries to the back and shoulders in industry.
INTEGRATED
ERGONOiMIC
OPERATOR-EQUIP.VENT
MODELS
KARL H. E. KROEMER(Ergonomics Laboratory, Department of Industrial Engineering and Operations Research, Virginia Tech University, Blacksburg, VA 21061, U.S.A.) Computerized models of human anthropometry and biomechanics are being used in research and teaching as well as for the design of manned systems in industry, military and space systems. A basic problem is that different universities, laboratories and industries use various models which have varying input requirements, disparate structures and data bases, and incompatible outputs. Although anthropometric, biomechanical and interface data are all necessary to the systematic equipment design process, they have never been integrated into a comprehensive ergonomic model of the human operator. Hence, there is incomplete understanding of the human as a system component. Development of an integrated ergonomic model of the human operator requires an overall conceptual framework to guide construction of the overall model itself as well as to guide systematic, interrelated research on its constituent parts. The Committee on Human Factors of the National Research Council conducted a two day workshop on 17 and 18 June 1985 to assess feasibility and requirements necessary to develop an integrated ergonomic model. This presentation reports on the points of view presented at the workshop. on the ensuing discussions. and on the results obtained.
REACH ANALYSIS USING THOMAS
DRAWING
BOARD
~MANIKINS ASD A MICRO-COMPUTER
J. ARMSTRONG and ROBERT G. RADWIN (The University of Michigan, U.S.A.) and Force Aero Medical Research Laboratory, U.S.A.)
KENNETH W. KENNEDY (Air
The availability of micro-computer equipment and CAD software makes it possible to evaluate anthropometric work requirements on a routine basis. The human body is depicted using stick figures that are constructed using CAD ‘line’ commands. The body also is depicted using two dimensional drawing board templates. Each segment is digitized and stored in file. A menu is created so that the files can be easily retrieved and the segments scaled and oriented at desired locations on work station drawings. ‘Arc’commands are used to construct reach envelopes to determine if controls, tools and materials can be reached without excessive postural stress. Additional research is required to validate predicted reach limits with empirical data, determine the limits ofa two-dimensional analysis, generate simplified templates and develop software to facilitate connecting the body links.