downwards relative to subject’s horizontal
eye level, there is an increase in (move
forward bending) head-neck flexion but
decrease in trunk forward flexion (more
upright posture). This suggests that a
comfortable visual distance is needed
in order to see the task position even
for a normal task which is not visually
demanding. Task is located within the
distance of 50-70 cm and at the height of
about 20 cm, below horizontal eye level
appears ideal.
Epidemiologic Study: Detection
of repetitive strain injuries
The goal of epidemiologic studies is
to identify factors that are associated
(positively or negatively) with the
development or recurrence of adverse
medical conditions. This evaluation and
summary of the epidemiologic evidence
focuses chiefly on disorders that affect the
neck and the upper extremity, including
tension neck syndrome, shoulder tendinitis,
epicondylitis, carpal tunnel syndrome, and
hand-arm vibration syndrome, which have
been the most extensively studied in the
epidemiologic literature. The relationship
between workplace factors and the
development of RSIs from epidemiologic
studies is classified into one of the following
categories:
Strong evidence of work-relatedness
(+++) – A causal relationship is shown
to be very likely between intense or long
duration exposure to the specific risk
factor(s) and RSI when the epidemiologic
criteria of causality are used. A positive
relationship has been observed between
exposure to the specific risk factor and
Repetitive Strain Injury in studies in which
chance, bias, and confounding factors could
be ruled out with reasonable confidence in
at least several studies.
Evidence of work-relatedness (++) –
Some convincing epidemiologic evidence
shows a causal relationship when the
epidemiologic criteria of causality for
intense or long duration exposure to the
specific risk factor(s) and Repetitive Strain
Injury are used. A positive relationship has
been observed between exposure to the
specific risk factor and Repetitive Strain
Injury in studies in which chance, bias,
and confounding factors are not the likely
explanation.
Insufficient evidence of work-relatedness
(+/0) –The available studies are of
insufficient number, quality, consistency,
or statistical power to permit a conclusion
regarding the presence or absence of a
causal association. Some studies suggest
a relationship to specific risk factors but
TASKS IN SEWING OPERATIONS
Sewing operations are most vulnerable to RSI, different operations pose different
degrees of vulnerability to forces and repetitions. The following table gives an example
of workplace factors and body parts affected for different operations.
Legend: “X” in any cell means significant. A blank in any cell means
insignificant.
Note: - The repetitions indicated in this table are only for elected tasks elements
and based on an 8-hour shift. It is important to realize that the total repetitions
of all task elements would be far greater than indicated in this table.
Tasks
High
Forces
L
S i d e S e a m
High
Repetitions
R
X
L
Extreme
Postures
R
X ( 1 3 2 0 )
Low
Back
L
R
X
L o a d i n g X ( 6 9 0 0 ) X H e m P a n t L e g s X ( 1 2 6 0 ) X X
Sew Buttons of Cuffs X 4 8 0 0 - 6 0 0 0 X X
X ( 4 8 0 0 ) X X ( 2 7 0 0 ) X
F o l d i n g X ( 1 4 0 0 - 2 1 6 0 ) X
Pins Only X
Bag Pockets X
Waistband X
R
L
Hand
R
X
L
Thumb
R
X
X
X
X
X
X
X
L
R
X X
X X
X X
Pinch Pinch
X
X
X
X ( 1 4 2 4 ) X X X X
X(9840) X X X X
X X (3105) X X X X X ( 6120) X X X
X
X
L
X
X
X
X
R
Pinch
X
X
Fingers
X
X
X
X
X X
Wrist
X
X
T h r e a d C l i p p i n g Basting
L
X
B u t t o n i n g
S i d e B o d y
Shoulder
X
X
X
X X
X X
X X X X X X
X X X X X X
X
X
Source: AAMA Manual
NECK and NECK /
S H O U L D E R
Repetition Force
+ + + +
Posture
Combination Vibration
+ + +
+ / 0
S H O U L D E R + + + / 0 + + E L B O W + / 0 + + + / 0 + + +
+/0 +++
HAND / WRIST
(Carpal tunnel syndrome) ++ ++
HAND / WRIST (Tendinitis) ++ ++
++
HAND-ARM vibration
syndrome
B A C K
Evidence of no effect of work factors (-)
– Adequate studies consistently show that
the specific workplace risk factor(s)