Author : Abdulrahman M. Basahel

Poor working postures and task demands are common factors that affect human performance in a workplace , particularly in the industrial sector (i.e., assembly tasks). These factors can lead to performance deterioration and introduce musculoskeletal disorders (MSDs). The current research study examines the interaction effects of working postures and assembly task demands on human performance and MSDs. Seventy-five male participants (ages 21–26) performed a manual assembly task at four levels of working postures conditions simultaneously at two different levels of assembly task demands. The subjective assessments following the task, Borg-CR10 and NASA-TLX were completed. In addition, rapid upper limb assessment (RULA) was used to assess musculoskeletal disorders due to postural conditions. Heart rate (HR) and mean arterial pressure (MAP) were recorded continuously. The results indicated that the squatting posture condition led to poor performance with high assembly workload. HR and MAP increased considerably when the posture condition changed. The squatting and stooping posture conditions with low- and high-level task workloads had a more harmful impact from physiological stress than the sitting and standing conditions. The NASA-TLX and Borg-CR10 were affected significantly by the assembly task and changes in working postures. The results of the total RULA scores showed that the stooping and squatting conditions were very hazardous to individuals in terms of musculoskeletal disorders, particularly at a high level of assembly workload.

Keywords: Postures stress, performance, assembly task, RULA method, physiological stress, NASA-TLX, Saudis.

Article published in International Journal of Current Engineering and Technology, Vol.4, No.5 (Oct-2014)