title: Muscle activity, time to fatigue, and maximum task duration at different levels of production standard time.
abstract: [Purpose] This study investigated the variations in muscle fatigue, time to fatigue, and maximum task duration at different levels of production standard time. [Methods] Twenty subjects performed repetitive tasks at three different levels of production standard time corresponding to "normal", "hard" and "very hard". Surface electromyography was used to measure the muscle activity. [Results] The results showed that muscle activity was significantly affected by the production standard time level. Muscle activity increased twice in percentage as the production standard time shifted from hard to very hard (6.9% vs. 12.9%). The muscle activity increased over time, indicating muscle fatigue. The muscle fatigue rate increased for the harder production standard time (Hard: 0.105; Very hard: 0.115), which indicated the associated higher risk of work-related musculoskeletal disorders. Muscle fatigue was also found to occur earlier for hard and very hard production standard times. [Conclusion] It is recommended that the maximum task duration should not exceed 5.6, 2.9, and 2.2 hours for normal, hard, and very hard production standard times, respectively, in order to maintain work performance and minimize the risk of work-related musculoskeletal disorders.
authors: Department of Mechanical Engineering, University of Malaya, Malaysia.
authors: Nurhayati Mohd
authors: NM
authors: Nur
authors: Department of Mechanical Engineering, University of Malaya, Malaysia.
authors: Siti Zawiah Md
authors: SZ
authors: Dawal
authors: Department of Mechanical Engineering, University of Malaya, Malaysia.
authors: Mahidzal
authors: M
authors: Dahari
authors: Department of Anatomy, University of Malaya, Malaysia.
authors: Junedah
authors: J
authors: Sanusi
keywords: Muscle activity; Muscle fatigue; Task duration