A method for evaluating the biomechanical stresses resulting from manual materials handling jobs.
Chaffin-DB; Herrin-GD; Keyserling-WM; Garg-A
Am Ind Hyg Assoc J 1977 Dec; 38(12):662-675
Methodology for the evaluation of biomechanical stresses induced by common manual materials handling activities in industry was described. Manual materials handling activity was observed and systematically recorded through careful measurements of extreme body postures and hand forces. Body angles were used to describe the posture of a person for modeling. Muscle strengths for each angle were either measured or assumed from normative population distribution strengths, and the resultant torque estimates at each joint center were then determined by a computerized biomechanical strength model. The model evaluated muscular strength requirements of an activity relative to assumed worker population strengths. The output was a prediction of the proportion of men and women that could perform each task comprising the observed activity and the musculoskeletal system being most stressed and limiting. Four case studies were assessed to document the specific strength demands of jobs having known high injury and illness rates and to compare the types of illnesses and injuries with predicted stresses on the musculoskeletal system. Biomechanical analysis of a worker in cable manufacture indicated high strength requirements for knees and shoulders corresponding with the injury profile for the job. Analysis of a job requiring workers to service two machines used to insulate electrical wire indicated high peak strength requirements. A high musculoskeletal loading for upper extremities for jobs involving spot welding on a metal assembly line and using a plastics bonding apparatus were correlated with upper extremity fatigue and injury. The authors conclude that the analysis, together with frequency of musculoskeletal and contact injuries, justifies redesign of a job or its personnel selection.
NIOSH-Publication; NIOSH-Contract; Contract-099-74-0062; Occupational-hazards; Worker-health; Body-mechanics; Mathematical-models; Materials-handling; Endurance-tests; Workplace-studies; Physical-stress; Work-performance; Musculoskeletal-system
American Industrial Hygiene Association Journal
University of Michigan