Figure 1: 

Balance Model of Work System Misfit

individual has technologies available to perform specific job tasks. The capabilities of the technologies affect performance and also the worker's skills and knowledge needed for its effective use. The task requirements also affect the skills and knowledge needed. Both the tasks and technologies affect the content of the job and the physical demands the job makes on the person. The tasks with their technologies are carried out in a work setting that comprises the physical and the social environment. There is also an organizational structure that defines the nature and level of individual involvement, interaction and control.

The purpose of interventions to control musculoskeletal disorders is to reduce the stress load to eliminate strain. As discussed below, this can be done by modifying the elements of the work system shown in Figure 1. Another tactic to control musculoskeletal disorders is to increase the capacity of the individual to handle greater loads, thereby reducing the possibility of a misfit.

B. The Nature of Interventions to Control Musculoskeletal Disorders

There are a variety of actions that have been applied in the workplace for eliminating or reducing the occurrence of occupational musculoskeletal disorders. These include engineering redesigns, changes in work methods, administrative controls, training, organized exercise, work hardening, personal protective equipment, and medical management to reduce exposures. Some of these have been evaluated in research studies using both laboratory and field settings. The purpose of this paper is to characterize the nature of these research studies, evaluate their methodological soundness, and determine conclusions that can be made based on their strengths and weaknesses. We will first comment on the types of actions.

Engineering redesign aims to control exposures to the biomechanical risk factors for musculoskeletal injury. Engineering redesign has three main directions: (1) redesign of machinery, (2) providing assistive devices, and (3) tool redesign. Redesign of machinery deals with reducing exposure to biomechanical risk factors through modification of the machinery or the workstation. An example would be the use of adjustable tables to improve the postures of body parts (neck, shoulders, arms, hands, wrists, and back). Another would be the realignment of controls for better access that promotes less forceful activation with better body part postures.

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