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WORK. (1) In mechanics, the product of force and distance through which the force acts. (2) In medicine, a measure of physical or mental effort expended in any task. Physical work results in metabolic activity locally and/or systemically. In biomechanics, physical work is classified as positive work (q.v.), negative work (q.v.) or isometric work (q.v.). Isotonic work, used in physiology, means under a constant tension.
WORK MEASUREMENT. In biomechanics, the application of work physiological methods to the measurement of task severity and/or conjointly with the construction of a biomechanical profile (q.v.) for a task or individual in the evaluation of the compatibility of the available and demanded motions inventories (q.v.).
WORK METABOLISM. Physiological energy consumption ascribable to the performance of a specific task in excess of resting metabolism (q.v.). Usually expressed as an index of energy consumed per unit time, e.g., calories per minute. In industry, working metabolism is obtained by analysis of respiratory gas exchange.
WORK PHYSIOLOGY. Application of principles of physiology to ergonomics (q.v.) and industrial engineering in design of tasks and workplace. Concerned with moderation of metabolic cost (q.v.), measurement and prevention of harmful work strain (q.v.). Uses physiological measurements of gas exchange, pulmonary ventilation (q.v.), metabolism (q.v.) and heart rate to measure the effects of workplace-related environmen tal stress vectors.
WORK STRAIN. The natural physiological response reaction of the body to the application of work stress (q.v.). The locus of the reaction may often be remote from the point of application of work stress. Work strain is not necessarily traumatic but may appear as trauma when excessive, either directly or cumulatively, and must be considered by the industrial engineer in equipment and task design. Thus, increase of heart rate is non-traumatic work strain resulting from physical exertion, but tenosynovitis (q.v.) may represent pathological work strain resulting from undue work stress on a tendon and/or its sheath.
WORK STRESS. Biomechanically, any external force acting on the body during the performance of a task. It always produces work strain (q.v.). Application of work stress to the human body is the inevitable consequence of performance of any task and is, therefore, only synonymous with “stressful work conditions” when excessive. Work stress analysis is an integral part of task design.
WORK TOLERANCE. Span of time during which a worker can effectively perform a task without rest period at levels of physiological and emotional well-being acceptable to the individual and without pathogenesis. Work tolerance is affected by environmental inputs (q.v.), workplace layout (q.v.), and state of health.
WORKPLACE LAYOUT. The designed arrangement of a work situation comprising man, materials, equipment and the physical environment of the workplace. Optimally it should be the result of deliberate task design which considers the implications of ecological stress vectors on performance efficiency, occupational safety and health.
WRAPAROUND GRASP. One of five basic grasps of the hand. The grasped object is held against the palm by the fingers wrapped around it with the thumb opposing the index finger (holding a broomstick). The thumb is of minimal importance in this grasp, which is an innate aptitude of man. It requires almost no learning to apply. A straight wrist is needed for successful application. Flexion of the wrist “breaks” the strength of the grasp and may lead to accidents at the workplace.
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