Development of predictive model for stoop and squat postures on physiological and psychophysical responses in manual lifting tasks
Malaysia’s economic growth is led by several industrial sectors and it involves thousands of workers. Even with the increased use of automation and new technology, manual material handling (MMH) still exist in the industry due to high flexibility and low in cost. MMH contributed as major cause of...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2019
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/77760/1/FK%202019%2059%20IR.pdf |
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| Summary: | Malaysia’s economic growth is led by several industrial sectors and it involves
thousands of workers. Even with the increased use of automation and new
technology, manual material handling (MMH) still exist in the industry due to
high flexibility and low in cost. MMH contributed as major cause of work-related
musculoskeletal disorders (MSD) cases in Malaysia as high as 40%. Posture
and weight load identified as the leading ergonomic risk factors to MSD during
the MMH task. Posture and weight load identified as the leading ergonomic risk
factors to MSD during the MMH task. Frequently used postures, stoop and
squat were studied since most researchers come to argument about the correct
technique as squat were presumed the safest way to lift but stoop were
preferred by most workers. The main objective of this study is to develop a
predictive model of MAWL for stoop and squat postures in MMH task. The
effects of load, frequency and height on both postures were identified together
with the effect of physiological and psychophysical responses on male and
female subjects. The methodology applied uses a total of 36 healthy male and
female subjects between the ages of 20 to 35 years. The experimental lifting
task was designed based on different load weights, heights and frequency
(independent variables). The effects of the independent variables on
physiological (heart rate and energy expenditure) and psychophysical (rating of
perceived exertion (RPE) and maximum acceptable weight limit (MAWL))
responses were studied. The predictive models were developed based on the
independent and dependent variables analysis. The results showed that the
load, frequency and height were significant factors with physiological and
psychophysical response of stoop and squat postures. Heart rate, energy
expenditure and RPE increases as the load, frequency and height increase.
Meanwhile, MAWL decreases as the frequency and height of lifting increases
in both postures. Stoop denote higher MAWL than squat posture as it produces
lower heart rate and energy expenditure compared to squat. The significant factors (p<0.05) associated with the MAWL predictive models are subjects,
height, heart rate and energy expenditure. The model significantly linear
towards the stoop (R = 0.957) and squat (R = 0.922). MAWL predictive model
successfully demonstrates and provides guidelines in evaluating the safe loads
and without exceeding the limits of the workers in stoop and squat lifting
postures during MMH task. |
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