Introduction- Numerous studies
have shown that operating a sewing machine is related to complaints in the left
shoulder, the neck and the back (eg. Vihma et al. 1982). These complaints may
be caused or aggravated by the working posture which is characterized by an
elevated left upper arm position, and a flexed position of the head and trunk.
At a traditional sewing machine workplace the body posture is constrained by
(1) the eyes for visual control of the work, (2) the hands to direct the sewing
material and (3) the foot to control the speed of the machine. In order to improve
the working posture and reduce the number of complaints, quantitative ergonomic
guidelines for adjustment and redesign of sewing machine workplaces are needed
which take these postural constraints into account. At present only a preliminary
guideline for table height at a sewing machine workplace exists. Dul et al.
(1989) found that a table height 5 cm above elbow height induces a better working
posture as compared to lower tables. Even higher tables are expected to improve
the head and trunk posture, but also to create a more elevated position of the
left upper arm. To resolve this classical problem the table desk can be given
a slope. This may induce a more upright posture of the head and trunk, without
elevating the arms and loading the shoulder region any further, as seen in various
settings (e.g. Bendix and Hagberg, 1984). Wick and Drury (1986) have shown the
positive effect of an inclined table desk on the working posture for sewing
work at a so-called single-post sewing machine in the apparel industry. No guidelines
are available for the position of the pedal in the forward-backward direction.
The purpose of the present study was to formulate guidelines for adjustment
and redesign of sewing machine workplaces in order to improve working posture
and to reduce the load on the musculoskeletal system. The relevant variables
are: table height, table slope and pedal position.