Background Fatigue among distribution network live-line workers in complex operational environments has become increasingly severe and requires widespread attention. Objective To investigate the positive rates of fatigue and associated influencing factors of live-line power distribution workers, and to make a reasonable strategy to reduce the fatigue of front-line workers. Methods Power supply companies in Guangdong, Guangxi, and Yunnan provinces were selected by cluster sampling in 2023, and all front-line live-line workers in the selected companies were recruited. The questionnaire used in this study consisted of two parts: one was the Fatigue Scale-14 (FS-14) for investigating fatigue status and the other was for associated influencing factors. A FS-14 score greater than 3 points was defined as fatigue. \begin{document}$ {\chi }^{2} $\end{document} test and logistic regression were employed to analyze the factors affecting fatigue. Results A total of 1341 questionnaires were distributed, and 1217 valid questionnaires were recovered, with a valid response rate of 90.75%. The average fatigue score of the participants was (6.84±3.79) points, and a total of 1054 participants scored over 3, resulting a fatigue positive rate of 86.6%. The logistic regression model showed that working under extreme weather (OR=2.03, 95%CI: 1.38, 2.98), overtime 2-3 times a week (OR=5.24, 95%CI: 1.28, 21.40), overtime everyday (OR=6.95, 95%CI: 1.71, 28.27), frequent wrist rotation (OR=1.95, 95%CI: 1.08, 3.51), and leaning back slightly (OR=2.94, 95%CI: 1.19, 7.28) associated with higher positive rates of fatigue. Conclusion The high positive rate of fatigue among live-line power distribution workers suggests severe fatigue issues. Extreme weather conditions, working overtime frequency, and maintaining wrist rotation and backward bending postures during work are main factors affecting their fatigue.

Background When live working line operators engage in upper limb operations, working for a long time with raising arms and the exposure to adverse ergonomic factors tend to increase muscle load, cause fatigue accumulation, and increase the risk of work-related musculoskeletal disorders (WMSDs). Objective To analyze work posture and associated muscle fatigue during executing breaking/connecting contact terminal, and identify adverse ergonomic factors of the work process. Methods This study recruited 10 volunteers to perform breaking/connecting contact terminal simulation. At a distance of 4.5, 3.5, and 2.5 m from the body to the wire, each performed the task 5 times. Visual 3D was used to analyze the kinematic data from motion capture. The surface electromyography (sEMG) signals of the deltoid, biceps, triceps, and brachioradialis were recorded during the simulation and analyzed for muscle fatigue using root mean square (RMS), median frequency (MF), and jointed EMG amplitude and spectrum analysis (JASA). After completion of each task, Borg scale was used to query the volunteers of their subjective fatigue. A 2-min rest was required between each distance. Results The kinematic data from motion capture showed that in the entire process of the task, the right upper limb was higher when lifting, with the right shoulder joint maintaining flexion and fluctuating periodically between abduction and adduction, external and internal rotation, the right elbow joint maintaining flexion and supination. The frequency of task cycle showed a significant effect on the Borg scale scores (P<0.001, partial \begin{document}$ {\eta }^{2} $\end{document}=0.464); the distance showed no significant effect on the Borg scale scores (P>0.05, partial \begin{document}$ {\eta }^{2} $\end{document}=0.002); their interaction effect was not significant (P>0.05, partial \begin{document}$ {\eta }^{2} $\end{document}=0.020). The results of the sEMG signals showed that at a distance of 4.5 m, the volunteers had the highest percentages of maximal voluntary electrical activation (MVE%) in the deltoid and right brachioradialis and the lowest MF values in the deltoid and left brachioradialis after completing 5 task cycles. The results of JASA showed that fatigue was observed in brachioradialis and deltoid after completing 5 task cycles at a distance of 4.5 m, the right deltoid and right brachioradialis at a distance of 3.5 m, in the brachioradialis, deltoid, and left bicep at a distance of 2.5 m. Conclusion The subjective fatigue of workers who engaged in breaking/connecting contact terminal elevates with more repetitive operations. Based on the sEMG and motion capture analysis, it can be found that improper distance between the workers and the target work area can increase the burden from poor posture and improper use of work equipment, and lead to muscle fatigue; the deltoid and brachioradialis are the key muscles of fatigue in this type of operation; changing the angle of the elbow joint and the shoulder joint during the process of the operation can affect the deltoid and brachioradialis exertion and loading.

Background Power grid is an important component of the national infrastructure. The occupational health issues among the workers in this industry are attracting great concern nationwide. Objective To investigate the prevalence of work-related musculoskeletal disorders (WMSDs) in neck and shoulder among the power distribution workers of power supply enterprises, and analyze the related influencing factors. Method In April 2023, a total of 1244 workers in 50 municipal power supply bureaus were randomly selected from the three provinces under China Southern Power Grid using cluster sampling method. The questionnaire used in the study was based on a revised Musculoskeletal Disorders Questionnaire and added ergonomic load of upper limb work. \begin{document}$ {\chi }^{2} $\end{document} test and logistic regression model were used to explore the influencing factors of neck pain and shoulder pain among the subjects. Results A total of 1244 valid questionnaires were recovered and the effective recovery rate was 90.87%(1244/1369). The positive rates of neck pain and shoulder pain were 45.5% (566 cases) and 36.3% (452 cases) respectively. The logistic regression analysis results showed that more than 20 years working age (OR=2.27, 95%CI: 1.39, 3.96; OR=2.56, 95%CI: 1.53, 4.26), often (OR=2.08, 95%CI: 1.35, 3.20; OR=2.40, 95%CI: 1.50, 3.58)/quite often (OR=2.96, 95%CI: 1.73, 5.04; OR=2.72, 95%CI: 1.49, 4.94) maintaining a forced posture, and working immediately after break (OR=1.72, 95%CI: 1.04, 2.85; OR=2.14, 95%CI: 1.19, 3.88) were associated with a higher positive rate of neck pain and shoulder pain respectively. Feeling sufficient rest (OR=0.61, 95%CI: 0.47, 0.80; OR=0.63, 95%CI: 0.50, 0.83) and opportunity to decide when to take breaks (OR=0.72, 95%CI: 0.53, 0.98; OR=0.62, 95%CI: 0.41, 0.93) were associated with a lower positive rate of neck pain and shoulder pain respectively. Conclusion The positive rates of neck pain and shoulder pain are high among power distribution workers. The main influencing factors included long working age, quite often maintaining a forced posture, and working immediately after break.