HAVE YOUR SAY BREAKING NEWS
Tell us your news by emailing at
[email protected] To read the latest sustainability news, go to
http://news.apparelresources.com/sustainability-news/
Ergonomics in Apparel Manufacturing – III
REPETITIVE STRAIN INJURY
Earlier in the first article of the five-part series on ergonomics, Dr. Prabir Jana had discussed the importance and impact
of ergonomics and its different facets in apparel manufacturing. In the second article, the writers N. Karthikeyan and
K. Mohankumar from the Bannari Amman Institute of Technology discussed the wrong posture and risk analyses of workers
leading to strain injuries in day-to-day operations in apparel manufacturing. In this third article, Dr. Prabir Jana, NIFT Delhi
highlights the cumulative trauma disorders and its interrelation with posture. He also talks about the rationale and science
behind the genesis of problems to understand the cause, and finding preventive measures to overcome the same.
M
any workplace factors influence
repetitive motion problems which
lead to strain, and thus injury. The three
main factors that cause strain injuries due
to repetitive motion (also called Repetitive
Strain Injuries or RSI) are Force, Repetition
and Posture. Force is the pressure exerted or
encountered; Repetitions are related to cycle
time; and Postures concern the position of
the body while performing a given operation.
Other factors that lead to strains and injuries
are – inadequate training, incentives given to
work for longer hours, change in method or
product model and physical condition of the
worker such as pregnancy, menopause and
hysterectomy. Acceleration is emerging as an
additional workplace factor, especially related
to the upper extremities.
According to ergonomic definition, a Repetitive
Strain Injury or RSI is an injury to a part of
the body caused by overusing or straining that
body part. The body gets strained when the
body parts are put to hard work, stretched
farther, put to greater impact, directly or
otherwise, and is made to function at a level
higher than it was prepared for. The immediate
impact may be minor, but when it occurs
repeatedly, the constant straining becomes a
cause for damage. The term Repetitive Strain
Injury identifies a group of conditions that
result from using the body in a way it is not
designed for or capable of comfortable working.
Repetitive Strain Injuries also has been
described as painful and limiting soft tissue
failures that result from repeated or continuous
application of slight to moderate physical stress
over extended period of time.
Other terms that are used interchangeably with
Repetitive Stress Injury (RSI) are Repetitive
Stress Disorder (RSD), Repetitive Strain
Disorder (RSD), Repetitive Motion Injury
Wrist pronation while working in buttonhole or button stitch machine
(RMI), Repetitive Motion Disorder (RMD), and
Cumulative Trauma Disorder (CTD). Another
term Musculoskeletal Disorders (MSDs), to be
more specific, a Work-related Musculoskeletal
Disorder (WMSD), refers not only to conditions
that involve the nerves, tendons, muscles, and
supporting structures of the body, but also used
interchangeably with RSI.
Forces and Repetitions
Forces and repetitions are two interrelated
factors. A force is considered low when average
adjusted force (mean + variance) = 6.6 pounds
+/- 3.52 pounds. While average adjusted force
(mean + variance) of 27.94 pounds +/- 18.92 is
considered as high force.
A task is considered repetitive if the cycle time
is less than 30 seconds and task is performed
for more than 50% of the work shift.
One of the revolutionary researches by
Tom Armstrong shows that cases of Repetitive
Strain Injury in low force and low repetition
operations are rare while that of high force and
high repetition is maximum.
52 Apparel Online Bangladesh | MAY 2017 | www.apparelresources.com
Ackward shoulder angle while handling
material during sewing
However, it is important to understand two
important factors that determine the risk
of Repetitive Strain Injury (RSI) in workers
operations: firstly, the number of times the
forces are exerted during the course of the
work day; and secondly, the position of the body
part which exerts or encounters the force.
The National Institute for Occupational
Safety and Health (NIOSH), USA document
established the epidemiologic evidence of the
relationship between selected RSI of the upper
extremity and the low back and exposure to
physical factors at work. The Bureau of Labour
Statistics (BLS) of the US Department of
Labour reported in 1990 that of all the reported
cases of occupational illness, 56% were
associated with repeated strain injuries. The
body parts affected was shoulder (6%), wrist
(51%), hand – excluding fingers (6%), and other
body parts (37%). In 1997, the NIOSH reported
that about 7,00,000 cases (or 32%) were the
result of repetitive motion or overexertion. It
also reported that RSIs accounted for 14% of
physician visits and 19% of hospital stays.