Diversity and variation in biomechanical exposure: What is it, and why would we like to know?

doi:10.1016/j.apergo.2006.04.006

Applied Ergonomics

Volume 37, Issue 4, July 2006, Pages 419-427

https://doi.org/10.1016/j.apergo.2006.04.006 Get rights and content

Abstract

Trends in global working life suggest that the occurrence of jobs characterized by long-lasting low-level loads or repetitive operations is increasing. More physical “variation” is commonly believed to be a remedy against musculoskeletal disorders in such jobs. One aim of the present paper was to shortly review the validity of this conviction. An examination of the available epidemiologic literature pointed out that the effectiveness of initiatives like job rotation or more breaks is weakly supported by empirical evidence, and only for short-term psychophysical outcomes. Only a limited number of studies have been devoted to physical variation, and concepts and metrics for variation in biomechanical exposure are not well developed. Thus, as a second objective, the paper proposes a framework for investigating and evaluating aspects of exposure variation, based on explicit definitions of variation as “the change in exposure across time” and diversity as “the extent that exposure entities differ”. Operational methods for assessing these concepts are also discussed.

Section snippets

Variation and diversity in contemporary work

Contemporary working life in the industrialized world is characterized by several trends that have a profound influence on the physical load (biomechanical exposures) of workers in general and the variability of these loads in particular.

Companies in industry as well as in the service sector increasingly outsource segments of their production, including administrative and supportive tasks, to sub-contractors, and rationalize the remaining core production towards a larger reliance on automation

Diversity, variation, health and well-being

Several physiologic hypotheses have been proposed of why certain exposure patterns would, in the long term, lead to musculoskeletal disorders (Visser and Van Dieën, 2006). Most of these theories imply that posture and load variation is beneficial to health. In particular, proper recovery of muscles is believed to be of crucial importance for avoiding disorders. In that context, the generic purpose of exposure variation is to give populations of motor units that would otherwise be overloaded an

What is diversity and variation?

According to the Concise Oxford English Dictionary (Thompson, 1995), vary means “make different” or “undergo change,” and variation is described as “the act or an instance of varying” or “departure from a former or normal condition.” Thus, “variation” is intimately associated with change, implicitly across time. In the context of biomechanical exposures, a reasonable definition of the concept variation would then be “the change in exposure across time.” With this definition, variation focuses

Measuring variation and diversity

While methods for assessing biomechanical exposure levels are well developed in the ergonomics literature, less attention has been paid to measuring exposure diversity and variation in consistent and standardized ways (Mathiassen and Christmansson, 2004). The proposed definition of variation—“the change in exposure across time”—implies that the issues of how fast and how much a particular exposure changes, and whether it exhibits recurring, similar elements, all qualify as aspects of variation.

Conclusions

More physical variation is commonly suggested to be an effective intervention against musculoskeletal disorders in jobs with low-level, long-lasting loads or repetitive operations. The present literature review points out that the empirical evidence for this conviction in intervention studies or epidemiology is weak. Some studies have shown beneficial effects of increased break allowances on short-term discomfort, while very few studies have been aimed at the long-term effects of initiatives

References (80)

S. Bao et al.
Ergonomic effects of a management-based rationalization in assembly work—a case study
Appl. Ergon.
(1996)
M. Christmansson et al.
Task design, psycho-social work climate and upper extremity pain disorders—effects of an organisational redesign on manual repetitive assembly jobs
Appl. Ergon.
(1999)
P.G. Dempsey et al.
On the evolution of task-based analysis of manual materials handling, and its applicability in contemporary ergonomics
Appl. Ergon.
(2006)
E.A.C. Fernström et al.
Alterations in shoulder muscle activity due to changes in data entry organisation
Int. J. Ind. Ergon.
(1999)
L. Finsen et al.
Musculoskeletal disorders among dentists and variation in dental work
Appl. Ergon.
(1998)
C. Gaudart
Conditions for maintaining ageing operators at work—a case study conducted at an automobile manufacturing plant
Appl. Ergon.
(2000)
C.T. Hye-Knudsen et al.
Trunk motion characteristics during different patient handling tasks
Int. J. Ind. Ergon.
(2004)
K. Kazmierczak et al.
An integrated analysis of ergonomics and time consumption in Swedish ‘craft-type’ car disassembly
Appl. Ergon.
(2005)
Å. Kilbom
Repetitive work of the upper extremity: part II—the scientific basis (knowledge base) for the guide
Int. J. Ind. Ergon.
(1994)
S. Konz
Work/rest: part II—the scientific basis (knowledge base) for the guide
Int. J. Ind. Ergon.
(1998)

C. Larivière et al.

The effect of sampling frequency on EMG measures of occupational mechanical exposure

J. Electromyogr Kinesiol.

(2005)

L. McLean et al.

Computer terminal work and the benefit of microbreaks

Appl. Ergon.

(2001)

H. Ólafsdottir et al.

Increase in musculoskeletal symptoms of upper limbs among women after introduction of the flow-line in fish-fillet plants

Int. J. Ind. Ergon.

(1998)

G. Palmerud et al.

Consequences of trapezius relaxation on the distribution of shoulder muscle forces: an electromyographic study

J. Electromyogr Kinesiol.

(1998)

B. Visser et al.

Pathophysiology of upper extremity muscle disorders

J. Electromyogr Kinesiol.

(2006)

D.A. Winter et al.

EMG profiles during normal human walking: stride-to-stride and inter-subject variability

Electroenc. Clin. Neurophysiol.

(1987)

D. Anton et al.

Method for quantitatively assessing physical risk factors during variable noncyclic work

Scand. J. Work Environ. Health

(2003)

G. Aronsson

Influence of worklife on public health

Scand. J. Work Environ. Health

(1999)

S.E. Bechtold et al.

Maximization of labor productivity through optimal rest-break schedules

Manage. Sci.

(1984)

B. Bernard

Musculoskeletal Disorders and Workplace Factors. NIOSH Publication 97-141, second ed.

(1997)

C. Beynon et al.

Effects of activity-rest schedules on physiological strain and spinal load in hospital-based porters

Ergonomics

(2000)

P.M. Bongers

The cost of shoulder pain at work

BMJ

(2001)

Buckle, P., Devereux, J., 1999. Work-related neck and upper limb musculoskeletal disorders. Issue 201, Luxembourg,...

A. Burdorf

Identification of determinants of exposure: consequences for measurement and control strategies

Occup. Environ. Med.

(2005)

EN 1005-3. Safety of Machinery—Human Physical Performance—Part 3: Recommended Force Limits for Machinery Operation

(2001)

D. Colombini

An observational method for classifying exposure to repetitive movements of the upper limbs

Ergonomics

(1998)

A.J. Dababneh et al.

Impact of added rest breaks on the productivity and well being of workers

Ergonomics

(2001)

K. Davis et al.

Ergonomics. Pros and cons of job rotation as a means of reducing injury costs

J. Occup. Environ. Hyg.

(2005)

P. Docherty et al.

Creating Sustainable Work Systems: Emerging Perspectives and Practice

(2002)

N. Fallentin et al.

Evaluation of physical workload standards and guidelines from a Nordic perspective

Scand. J. Work Environ. Health.

(2001)

M.B. Frazer et al.

The effects of job rotation on the risk of reporting low back pain

Ergonomics

(2003)

T.L. Galinsky et al.

A field study of supplementary rest breaks for data-entry operators

Ergonomics

(2000)

A.M. Genaidy et al.

Active microbreak effects on musculoskeletal comfort ratings in meatpacking plants

Ergonomics

(1995)

R.W. Glenny et al.

Applications of fractal analysis to physiology

J. Appl. Physiol.

(1991)

M. Hagberg et al.

Discomfort and load on the upper trapezius muscle when operating a wordprocessor

Ergonomics

(1986)

M. Hagberg

Exposure variables in ergonomic epidemiology

Am. J. Ind. Med.

(1992)

R.A. Henning et al.

Microbreak length, performance, and stress in a data entry task

Ergonomics

(1989)

R.A. Henning et al.

Frequent short rest breaks from computer work: effects on productivity and well-being at two field sites

Ergonomics

(1997)

U. Hinnen et al.

Design of check-out systems including laser scanners for sitting work posture

Scand. J. Work Environ. Health

(1992)

M. Jarvi et al.

Job rotation in nursing: a study of job rotation among nursing personnel from the literature and via a questionnaire

J. Nurs. Manage.

(2004)

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