Development of a safety index for manual lifting tasks.
Karwowski W; Mital A
Appl Ergon 1986 Mar; 17(1):58-64
A proposed safety index for assigning workers to specific lifting tasks was described. The index was based on the combined effects of biomechanical and physiological stress responses of a worker to a particular job. The index could be written as the product of two terms. The first term was the ratio of the predicted compressive force on the L5/S1 disc of the spine to a reference value for the biomechanical stress. The second was an exponential term whose value depended on the oxygen consumption associated with lifting a specified load at a certain frequency and a reference value for physiological stress. The reference values of the physiological and biomechanical stresses were obtained from the literature. Numerical examples were given. These showed that safety index values could be used for designating certain actions for lifting loads. For example, a job requiring continuous lifting of 26.6 kilogram loads, at the rate of eight lifts per minute, had a safety index value of reducing the weight to be lifted or reducing the frequency of lift. The authors note that the concept of safety index, because it deals with individual lifting capacities, differs from the conventional approach of determining lifting capacity norms based on a specific population percentile.
Safety-measures; Biomechanics; Work-analysis; Skeletal-stress; Musculoskeletal-system; Skeletal-movement; Physiological-function; Ergonomics; NIOSH-Publication; NIOSH-Grant; Manual-lifting; Manual-materials-handling
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