Fatin Ayuni Mohd Azli Lee’s research while affiliated with Technical University of Malaysia Malacca and other places

Manual material handling (MMH) activities utilize human’s effort with minimal aid from mechanical devices. MMH is typically associated with poor lower back posture which can lead to lower back injury. The likelihood to develop musculoskeletal disorders (MSDs) increases when poor working posture exist in combination with repetition and/or forceful exertion. In manual transfer activity, the distance between lifting origin and destination could affect workers’ exposure on poor lower back working posture. An experimental study was conducted to investigate the effect of transfer distance to lower back twisting and bending pattern in manual transfer activity. Positional body joints data of 26 male subjects were captured using the combination of motion capture (MOCAP) system with MVN studio software. Calculated data were plotted against time to track subjects’ lower back twisting and bending behavior. In general, longer the transfer distance would result in smaller twisting angle but higher bending angle. Statistical analysis in this study suggests 0.75m to 1.00m as the optimum transfer distance to balance lower back twisting and bending exposure on workers. This study is envisioned to provide insights for practitioners to consider space requirements for MMH activity to minimize lower back twisting and bending, and consequently the development of MSDs.

Manual material transfer tasks are common in occupational settings. Repetitive lifting tasks usually involve twisting and bending which are associated with occupational lower back injuries. One of the approaches to reduce bending and twisting is to separate the distance between lifting origin and destination, which will encourage lifters to step and turn entire bodies. However, adding lifting distances is likely to affect space usages and requirements. A study was conducted to investigate how the transfer distances influence space usage during the lifting task. Raw data of hip and hand wrists motion of 26 male subjects during transfer in 4 different distances were captured using X-Sens motion capture system. MVN Studio software was used to process and extract positional data. Tabulated space mapping revealed limited hip movement and semicircular shaped hand motions for short transfer distances. The pattern changes into a more stretched-curve shape as the distance increases. Overall, it was observed that shorter transfer distance caused participants to adopt more twisting and less bending postures, while further transfer distances resulted in more bending and less twisting. This study may provide industrial practitioners with information to design a space requirement for manual material transfer tasks. ABSTRAK: Kerja-kerja pemindahan barang secara manual adalah biasa dalam persekitaran kerja. Kerja-kerja mengangkat barang yang kebiasaannya melibatkan badan membengkok dan berpusing boleh menyebabkan kecederaan tulang belakang. Salah satu cara bagi mengurangkan risiko ini adalah dengan memisahkan jarak antara tempat asal dan tempat tuju pemindahan barang. Pemindah barang digalakkan untuk melangkah dan memusingkan seluruh badan. Namun, cara ini menyebabkan penggunaan ruang yang banyak. Satu kajian telah dijalankan bagi mengkaji bagaimana jarak pemindahan barang mempengaruhi penggunaan ruang ketika kerja-kerja pemindahan. Data asal pergerakan pinggul dan pergelangan tangan daripada 26 subjek lelaki ketika pemindahan barang pada 4 jarak berbeza diperolehi menggunakan sistem rakaman gerakan X-Sens. Perisian MVN Studio digunakan bagi memproses dan mengekstrak data ini. Ruang pemetaan berjadual mendedahkan pergerakan pinggul yang terhad dan pergerakan tangan berbentuk separa bulat pada jarak pemindahan terdekat. Corak ini berubah kepada bentuk lengkung memanjang apabila jarak bertambah. Keseluruhannya, jarak pindahan yang kurang menyebabkan para peserta lebih terdedah kepada postur memusingkan badan berbanding membengkok, sementara jarak yang jauh menyebabkan peserta lebih membengkok berbanding memusingkan badan. Kajian ini memberikan maklumat untuk penggiat industri mereka cipta keperluan ruang bagi kerja-kerja pemindahan barang secara manual.