Characteristics of work actions of shoe manufacturing assembly line workers and a cross-sectional factor-control study on occupational cervicobrachial disorders.

Abstract

The characteristic work actions of female shoe manufacturing assembly line workers were analyzed by the records of 8-mm cine-films. The relationship between cervicobrachial disorders and work actions was investigated as a cross-sectional factor control study by using sex-age matched pairs for non-assembly line workers (102 pairs). The following conclusions were obtained:1) The assembly line workers handled about 3,400 sneaker shoes per day on the assembly line. A completed shoe weighed 200-500g.The metal last weighed 400-1,200g. As the lines were not com pletely mechanized, the workers passed shoes to the next worker by hand.2) In the line selected for the study of work actions, 28 female workers and one male worker were engaged. The work direction of the line was one-way (from left to right or vice versa). The actions of the workers were classified into four fundamental actions: i) grasping the shoe or tool, ii) extending or iii) bending of the arms, and iv) keeping the arms in a certain position. These fundamental actions were repeated more than 3,400 times per day by each worker. The time spent in holding a shoe in the left hand was longer than that of the right hand in holding a shoe or tool.3) Results of medical examinations showed a higher prevalence in assembly line workers than that in non-assembly line workers. Especially the prevalence rate of tapping test, pain sensibility test, vi bratory sensibility test, Morley's test, tenosynovitis in the fingers, tendernesses at spinal muscle around the thoracic vertebrae, levator muscle of scapula, trapezius muscle, rhomboid muscle, infraspinatus mus cle, greater pectoral muscle, anterior scalene muscle, thenar eminence, biceps muscle of arm, brachioradial muscle, and antebrachial flexor muscle were found to be different significantly by McNemar's test be tween the two groups. These disorders were appeared in the left shoulder, arm and hand. 4) As the non-assembly line workers were not engaged in compulsory work or in one-way work direction, they injured the right side (skillful 'side). On the contrary, it is considered that compulsory transfer of shoes and one-way work direction imposes a heavier load on the left side of the body in as sembly line workers, and consequently they injured the left side more severely.

A conceptual model for work-related neck and upper-limb musculoskeletal disorders.

“…The "work relatedness" of musculoskeletal disorders is supported by numerous epidemiologic studies (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). (See table 1.)…”

Seasonal variation in neck and shoulder symptoms.

“…In cross-sectional studies, symptoms have been linked to jobs with highly repetitive shoulder muscle contractions, static contractions, and work above shoulder level (1)(2)(3)(4)(5). In addition to biomechanical factors, psychosocial elements such as poor job satisfaction have been associated with neck and shoulder symptoms (3,(6)(7)(8)(9).…”

A socio-technical approach for improving a Brazilian shoe manufacturing system

“…Studies on shoe manufacturing focusing on WMSD were developed by [5,21,23] in Japan, by [33] in Mexico, by [4,14] in Italy, by [11,12,15,36] in the USA, by [31] in France, by [28] in Brazil, by [13] in Romania, and by [19] in Cuba. Most studies concentrate on the evaluation of environment, tools and workstation conditions (i.e.…”