Ergonomic assessment of manual load carrying among women farm workers
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Date
2015
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DIVISION OF AGRICULTURAL ENGINEERING INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI
Abstract
In the work force of 480 million in India, 263 million workers are associated
with agricultural activities as compared to 220 million with industries and remaining
with service/other sectors. Of these 480 million, about 150 million (31.2 %) are
women workers. In agriculture alone, 100 million (37%) are women workers where
they perform various activities in agriculture, home and animal husbandry.
Agriculture activities are energy-intensive and are performed in harsh environment by
the manual labor. During these activities women farm workers are exposed to a
multitude of musculoskeletal disorder risk factors. The musculoskeletal structure is
subjected to three main risk factors in agricultural activities. These include: lifting and
carrying heavy loads, sustained or repeated full body bending (stoop); and highly
repetitive hand work (clipping, cutting, transplanting).
Carrying load for long distance is one of the daily routine work for farm
women workers in Indian agriculture. They carry water, fodder, cow dung on daily
basis and agricultural input and harvested produce on seasonal basis. In this context,
the present study was undertaken to ergonomically assess the impact of heavy load
carrying on the health of farm women workers of India. A survey was conducted at
Thanakalan village, Kharkhoda Block of Sonipat district in Haryana state to study the
load carrying activities. In this locality there were no industrial units, so farming was
the primary occupation. A house to house survey of forty farm women workers was
conducted. The result of the survey shows that musculoskeletal problem was the
major health problem among the women farm workers in different age groups. It was
observed that 38 out of 40 woman farm workers (95 %) had musculoskeletal disorder.
Carrying load (10 kg to 40 kg) by women farm workers was an everyday activity
which contributed to musculoskeletal disorders. Body parts discomfort shows that
lower back is the most affected body part, as 87.5 per cent women farm workers
complained of back pain, followed by neck pain (72.5 per cent) and knee and foot
pain. The pain severity was mild in most of the women farm workers and nobody was
bed ridden for back pain due to load carrying.
An experimental study of different modes of carrying different load (i.e. Head,
Back and Shoulder and 10, 15, 20 kg) on different ground inclination (i.e. 0, 5, 10 %)
was conducted in laboratory set up. Women working on local farm were selected and
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prepared to walk on treadmill. All the three modes were compared on the basis of
physiological parameters like heart rate (beats/min.), oxygen consumption (l/min) and
energy consumption (kJ/min).The results shows that head mode of carrying load on
horizontal surface is economical in terms of energy consumption irrespective of
quantity of load as compared to back and shoulder mode. On inclined surfaces (i.e. 5
and 10 % ground inclination) back mode of carrying load was less energy consuming
as compared to head and shoulder mode.
Biomechanical model was developed to predict metabolic energy cost for
carrying load in different modes and inclinations. The input variables required in
developed model were related to operator, inclination and load parameters. Operator
parameter includes human efficiency, body weight and height of the worker. Load
parameter includes weight of load and mode of carrying load. Positive inclination i.e.
upward slope was considered for experimental and modeling purpose. The developed
model had high co-relation(co-efficient of 0.95) between measured and predicted
values of metabolic energy consumption (kJ/min). User friendly interactive software
was also developed using C Sharp (C#) computer programming language.
Physiological study of different modes of carrying load and modeling for
energy consumption, revealed that head mode was economical mode in terms of
energy demand and physiological cost for carrying load on horizontal surface,
therefore preferred choice of farm worker as stated by them in survey. In most part of
the country, terrains are more or less flat. Shoulder mounted harness was designed for
women farm workers for carrying load which did facilitate load carrying similar to
head loading without introducing element of eccentricity. The harness was made up of
aluminium material to make it sturdy and light weight. There is a horizontal distance
adjustment at shoulder level up to 3cm. The upper load carrying platform is
detachable so, that it can be lifted with convenience. Belt arrangement is given at
waist and chest level for secure fastening. Cushion padding is provided on both
harness and belt at the point of contact with the body.
There was 0.5 to 6 % increase in energy consumption (kJ/min) with harness as
compared to carrying load directly on head. This is due to additional weight of
intervention and minor inconvenience of wearing harness. Though the head mode was
energy efficient but the stress in neck muscle and cervical spine did contribute to
cervical spondylitis, which is the major health risk. The design of the intervention is
such that instead of concentrating total weight of load on head a part of load is
transferred to shoulder, which is preventing direct loading of cervical spine.
Description
T-9158
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