National Research Centre for the Working Environment, Copenhagen, Denmark.
Department of Psychology, Lund University, Lund, Sweden.
Ann Work Expo Health. 2022 Aug 7;66(7):863-877. doi: 10.1093/annweh/wxac021.
To investigate and characterize the influence of sex, age, muscle strength, and cardiovascular fitness on manual lifting patterns using exposure variation analysis (EVA) during a full working day among blue-collar workers.
Muscular activity (surface electromyography [sEMG]) of the thigh, low-back, and shoulder was measured throughout the working day in 173 employees with manual lifting tasks from 14 workplaces. Relative sEMG loading was expressed as % of maximal voluntary contraction (MVC). As an additional and more practically oriented analysis, calibration of load from standardized box lifts (5, 10, 20, and 30 kg) identified corresponding sEMG values in kg. Using an EVA 'lifting periods' of [1 to 5, >5 to 10, >10 to 20, >20 to 30, and >30] kg in time intervals [0 to 0.5, >0.5 to 1, >1 to 2, >2 to 5, >5 to 10, and >10] s were identified. Arm elevation and back inclination were measured using accelerometers.
Females and older workers (≥50 years) primarily used the thighs for lifting and were exposed to more frequent thigh muscle 'lifting periods' of varying duration and load and performed more thigh lifts >30 kg and >60% of MVC compared with males and younger workers (P < 0.05). Females had less brief shoulder lifting periods and more work with bent back >30° than the males (P < 0.05), whereas stronger workers performed more work with elevated arm >60° and >90° than workers with low muscle strength (P < 0.05). However, besides a single difference where workers with lower cardiovascular fitness were exposed to more light (1-5 kg) and moderate duration (5-10 s) trapezius loading, the number of lifting periods was not affected by muscle strength nor cardiovascular fitness (P > 0.05).
This EVA demonstrated sex- and age-related differences in exposure to lifting periods involving shoulder and thigh muscles.
通过暴露变化分析（EVA）研究和描述性别、年龄、肌肉力量和心血管健康对蓝领工人全天手动举重模式的影响。
在 14 个工作场所的 173 名有手动举重任务的员工中，在整个工作日中测量大腿、下背部和肩部的肌肉活动（表面肌电图 [sEMG]）。相对 sEMG 负荷表示为最大自主收缩（MVC）的百分比。作为额外的、更实用的分析，从标准化箱式举重（5、10、20 和 30 公斤）中校准负荷，确定相应的 sEMG 值（kg）。使用 EVA“举重周期”[1 至 5、>5 至 10、>10 至 20、>20 至 30 和>30 至 50]kg 在时间间隔[0 至 0.5、>0.5 至 1、>1 至 2、>2 至 5、>5 至 10 和>10 至 20]s 中进行识别。使用加速度计测量手臂抬高和背部倾斜。
女性和年龄较大的工人（≥50 岁）主要使用大腿进行举重，并且更频繁地经历不同持续时间和负荷的大腿肌肉“举重周期”，并且与男性和年轻工人相比，他们进行了更多的>30kg 和>60%MVC 的大腿举重（P<0.05）。女性的肩部举重周期更短，弯腰>30°的工作更多，而男性则弯腰>30°的工作更多（P<0.05），而肌肉力量较强的工人进行的抬高手臂>60°和>90°的工作比肌肉力量较低的工人多（P<0.05）。然而，除了肌肉力量较低的工人暴露于更多轻（1-5kg）和中等持续时间（5-10s）斜方肌负荷的单一差异外，举重周期的数量不受肌肉力量或心血管健康的影响（P>0.05）。
该 EVA 显示了与性别和年龄相关的涉及肩部和大腿肌肉的举重周期暴露差异。
