Work-Related Musculoskeletal Risks And Electromyographic Analysis Of The Upper Body Muscles During Oil Palm Pruning Activities

• Main Author: Abdullah, Nadiah Aqilahwati
• Format: Monograph
• Language: English
• Published: Universiti Sains Malaysia 2021
• Subjects: T Technology; TJ1-1570 Mechanical engineering and machinery
• Online Access: http://eprints.usm.my/55997/1/Work-Related%20Musculoskeletal%20Risks%20And%20Electromyographic%20Analysis%20Of%20The%20Upper%20Body%20Muscles%20During%20Oil%20Palm%20Pruning%20Activities.pdf; http://eprints.usm.my/55997/
• Institution: Universiti Sains Malaysia

Work-related musculoskeletal disorders (WMSDs) risks are prevalent among oil palm workers. However, investigating the risks mainly relies on observational techniques that depend on the researcher’s interpretation. This study investigated the prevalence of WMSDs associated with various factors, muscle activation patterns, and muscle fatigue induced during the pruning tasks using reliable direct measurement methods. Two subjects with different levels of experience in palm pruning were recruited to perform pruning tasks using chisel and sickles. Xsens wearable inertial measurement units (IMU) were utilised in the motion analysis of the subjects. An automated Rapid Entire Body Assessment (REBA) based on the kinematic data acquired from wearable IMU was employed to identify postures exposed to a high-risk level comprehensively. Activation of the upper body muscles was analysed using iMotions wearable surface electromyography (EMG) sensor. Bipolar surface EMG electrodes were attached to seven upper body muscles (upper trapezius, middle trapezius, left and right biceps brachii, left and right middle deltoid, and erector spinae longissimus). A subjective perception regarding pain was obtained using a modified Nordic Musculoskeletal Questionnaire. From this study, extreme working postures in various articulations and highly repetitive movements were identified as the risk factors of WMSDs. REBA analysis showed medium to high-risk mean scores with all peak scores within the tasks fell in the high to very-high risk category. All muscles measured were activated together during the tasks with the greatest demand during the pruning using both cutting tools were on the upper trapezius, middle trapezius, and biceps brachii. Manifestation of fatigue on muscles was evidence in all pruning tasks, with the inexperienced subject had a higher rate of fatigue than the experienced subject. Regarding the subjective perception of pain, both subjects experienced pain in all selected body parts. Improvement in the working environments is required to reduce the risk of WMSDs and fatigue among the palm cutters. Further investigation with more sample sizes in an actual palm plantation is suggested for better effect size in portraying exposure to WMSDs, utilisation of muscles, and the manifestation of fatigue in muscles.