Key Laboratory of Advanced Manufacturing Technology of the Ministry of Education, Guizhou University, Guiyang 550025, China.
School of Mechanical Engineering, Southeast University, Nanjing 211189, China.
Int J Environ Res Public Health. 2021 May 20;18(10):5468. doi: 10.3390/ijerph18105468.
Manual material handling (MMH) is commonly demanded in the manufacturing industry. Occupational muscle fatigue of the arm, shoulder, and back, which arise from MMH tasks, can cause work absences and low efficiency. The available literature presents the lack of the fatigue comparison between targeted muscles, on the same part or on different parts. The main aim of the present study was to evaluate and compare the fatigue of upper-body muscles during repetitive bending tasks, an experiment involving 12 male subjects has been conducted to simulate material handling during furniture board drilling. The vertical lifting distance was chosen to be the single independent variable, and the three levels were 0, 250, and 500 mm. Surface electromyography (sEMG) was used to measure the muscle fatigue of the biceps brachii, upper trapezius, and multifidus, while the sEMG parameters, including the normalized electromyographic amplitude (Normalized EA) and mean power frequency (MPF), of the target muscles were analyzed. The experimental results reveal that during the manual handling tasks, the biceps brachii was the most relaxed muscle, contributing the least muscle tension, while the multifidus was the most easily fatigued muscle. Furthermore, the EMG MPF fatigue threshold (MPFFT) of multifidus muscle tension was tested to estimate its maximum workload in the long-term muscle contraction. In conclusion, bending angle should be maintained to a small range or bending should even be avoided during material-handling tasks.
手动物料搬运（MMH）在制造业中很常见。由于 MMH 任务，手臂、肩膀和背部的职业性肌肉疲劳会导致旷工和效率低下。现有文献缺乏对同一部位或不同部位目标肌肉的疲劳比较。本研究的主要目的是评估和比较重复弯曲任务中上肢肌肉的疲劳，为此进行了一项涉及 12 名男性受试者的实验，以模拟家具板钻孔过程中的物料搬运。垂直提升距离被选为唯一的独立变量，三个水平分别为 0、250 和 500mm。表面肌电图（sEMG）用于测量肱二头肌、上斜方肌和多裂肌的肌肉疲劳，同时分析目标肌肉的标准化肌电图幅度（Normalized EA）和平均功率频率（MPF）等 sEMG 参数。实验结果表明，在手动搬运任务中，肱二头肌是最放松的肌肉，肌肉张力最小，而多裂肌是最容易疲劳的肌肉。此外，还测试了多裂肌张力的肌电图 MPF 疲劳阈值（MPFFT），以估计其在长期肌肉收缩中的最大工作量。总之，在物料搬运任务中，应将弯曲角度保持在较小的范围内，甚至应避免弯曲。
