Yeung Simon S, Genaidy Ash, Deddens James, Leung P C
Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Hong Kong.
Int Arch Occup Environ Health. 2003 Sep;76(7):505-16. doi: 10.1007/s00420-003-0448-3. Epub 2003 May 29.
To determine the different cognitive strategies adopted by workers in assessing the effects of lifting-task parameters on effort, and to validate workers' assessments.
Questionnaires were administered to 217 male workers with varied levels of experience in manual handling. Workers were asked to assess the effects of lifting on perceived effort, using linguistic descriptors (e.g., light, heavy), and to determine the physical meaning of such descriptors. In addition, each worker assessed on-the-job effort, perceived risk of injury and work dissatisfaction, and musculoskeletal outcomes in a cross-sectional design.
Perceived physical effort was significantly associated with lifting variables. Results indicated that the three-cluster strategy is the best performer. Weight of load emerged as the most influential factor that impacted on effort in the most dominant cluster (close to 50% of the observations). The second cluster (25% of the observations) demonstrated that weight, horizontal distance, and twisting angle, contributed equally to effort, and the third cluster had weight and vertical travel distance as the most important variables (with travel distance being more important). Perceived effort was significantly associated with objective indices (i.e., biomechanical lifting equivalent and NIOSH lifting index), and musculoskeletal symptoms in eight body parts.
Cognitive reasoning of experienced workers may be used as an active device for the evaluation of strenuous physical activities such as lifting tasks. Lifting activities are significantly associated with musculoskeletal symptoms, not only in the lower-back region, but also in seven other body parts; and effort may integrate the effects of both physical (lifting tasks) and non-physical (i.e., work dissatisfaction) factors, as well as perception of risk.
确定工人在评估搬运任务参数对劳动强度的影响时所采用的不同认知策略，并验证工人的评估结果。
对217名具有不同体力劳动经验水平的男性工人进行问卷调查。要求工人使用语言描述词（如轻、重）评估搬运对感知到的劳动强度的影响，并确定这些描述词的物理意义。此外，在横断面设计中，每位工人评估了工作中的劳动强度、感知到的受伤风险、工作满意度以及肌肉骨骼状况。
感知到的体力劳动强度与搬运变量显著相关。结果表明，三聚类策略表现最佳。在最主要的聚类中（近50%的观察结果），负荷重量是影响劳动强度的最具影响力的因素。第二个聚类（25%的观察结果）表明，重量、水平距离和扭转角度对劳动强度的贡献相同，第三个聚类中重量和垂直移动距离是最重要的变量（移动距离更重要）。感知到的劳动强度与客观指标（即生物力学搬运当量和美国国家职业安全与健康研究所搬运指数）以及八个身体部位的肌肉骨骼症状显著相关。
经验丰富的工人的认知推理可作为评估诸如搬运任务等剧烈体力活动的有效手段。搬运活动不仅与下背部区域的肌肉骨骼症状显著相关，还与其他七个身体部位的症状相关；并且劳动强度可能综合了身体因素（搬运任务）和非身体因素（即工作满意度）以及风险感知的影响。
