Background High-speed train engineers' lower extremities are constrained by compulsive vigilance pedal tasks and limited space beneath the control console during driving. Shifts in alertness triggered by running route observation may share the same mental resource required by moderate-to-low physical exertion. Current research on improving cab design and maintaining optimal on-duty attention allocation remains limited. Objective To examine variations in lower extremity muscle load, gaze-tracking behavior, and driving performance under various combinations of vigilance pedal positions and route scenarios during simulated high-speed train tasks. To identify optimal working condition combinations that promote level and variety of physical activity and facilitate rational attention allocation. Methods A 4×2 within-subjects design were employed (4 vigilance pedal position profiles: knee front, side, and any; 2 route scenarios: monotonous and complex). Nine male college volunteers were recruited as simulated drivers to perform designated interval driving tasks. Surface electromyography and eye tracking were used to assess leg muscle load and gaze behavior respectively. Task performance and subjective fatigue were recorded. Results In all simulation driving tasks, skeletal muscle loads were low with the percentage of maximum voluntary contraction (%MVC) at approximately 4%. No fatigue tendencies were observed within single trial blocks (7 min), and the subjective fatigue ratings remained relatively low. While the activation of the dominant-side tibialis anterior was higher for the knee pedal than for the front (%MVC: 3.7% ± 3.13% vs. 1.08% ± 0.72%) or the side pedals (%MVC: 3.7% ± 3.13% vs. 1.4% ± 0.77%). The activation level of the dominant-side gastrocnemius was higher for the knee pedal than for the other three pedal profiles. For the any pedal condition, the intercept of the instantaneous median frequency curve for the dominant-side rectus femoris was lower in the monotonous route than in the complex route [(111.18 ± 35.78) Hz vs. (153.33 ± 39.12) Hz]. Among eye-tracking metrics, total fixations were higher during knee-level pedaling than side pedaling, while more saccades were recorded in monotonous routes than in complex ones. Regarding task performance, the any pedal yielded fewer missed signals than the front pedal, with 2/3 and 1/3 of participants preferring the front and knee pedals, respectively. The activation levels of the dominant tibialis anterior and dominant gastrocnemius muscles during the knee pedal × complex route combination were higher than any combination involving the front pedal. No statistically significant effect of pedal position or route scenario was found on other indicators. Conclusion The combination of knee pedal and complex route provides an optimal working setting for maximizing leg muscle mobility without compromising attention allocation or driving performance. It is recommended that train engineers modulate attention during monotonous routes to avoid emotional tension and increased muscle strain caused by over-monitoring. Given the ergonomic characteristics of high cognitive load, low physical exertion levels, and highly restricted lower limb mobility among high-speed train engineers, future cab designs should consider incorporating knee-level vigilance pedal and adjust safety alertness rules to allow reset via either front or knee pedal.

Background High-speed train engineers' lower extremities are constrained by compulsive vigilance pedal tasks and limited space beneath the control console during driving. Shifts in alertness triggered by running route observation may share the same mental resource required by moderate-to-low physical exertion. Current research on improving cab design and maintaining optimal on-duty attention allocation remains limited. Objective To examine variations in lower extremity muscle load, gaze-tracking behavior, and driving performance under various combinations of vigilance pedal positions and route scenarios during simulated high-speed train tasks. To identify optimal working condition combinations that promote level and variety of physical activity and facilitate rational attention allocation. Methods A 4×2 within-subjects design were employed (4 vigilance pedal position profiles: knee front, side, and any; 2 route scenarios: monotonous and complex). Nine male college volunteers were recruited as simulated drivers to perform designated interval driving tasks. Surface electromyography and eye tracking were used to assess leg muscle load and gaze behavior respectively. Task performance and subjective fatigue were recorded. Results In all simulation driving tasks, skeletal muscle loads were low with the percentage of maximum voluntary contraction (%MVC) at approximately 4%. No fatigue tendencies were observed within single trial blocks (7 min), and the subjective fatigue ratings remained relatively low. While the activation of the dominant-side tibialis anterior was higher for the knee pedal than for the front (%MVC: 3.7% ± 3.13% vs. 1.08% ± 0.72%) or the side pedals (%MVC: 3.7% ± 3.13% vs. 1.4% ± 0.77%). The activation level of the dominant-side gastrocnemius was higher for the knee pedal than for the other three pedal profiles. For the any pedal condition, the intercept of the instantaneous median frequency curve for the dominant-side rectus femoris was lower in the monotonous route than in the complex route [(111.18 ± 35.78) Hz vs. (153.33 ± 39.12) Hz]. Among eye-tracking metrics, total fixations were higher during knee-level pedaling than side pedaling, while more saccades were recorded in monotonous routes than in complex ones. Regarding task performance, the any pedal yielded fewer missed signals than the front pedal, with 2/3 and 1/3 of participants preferring the front and knee pedals, respectively. The activation levels of the dominant tibialis anterior and dominant gastrocnemius muscles during the knee pedal × complex route combination were higher than any combination involving the front pedal. No statistically significant effect of pedal position or route scenario was found on other indicators. Conclusion The combination of knee pedal and complex route provides an optimal working setting for maximizing leg muscle mobility without compromising attention allocation or driving performance. It is recommended that train engineers modulate attention during monotonous routes to avoid emotional tension and increased muscle strain caused by over-monitoring. Given the ergonomic characteristics of high cognitive load, low physical exertion levels, and highly restricted lower limb mobility among high-speed train engineers, future cab designs should consider incorporating knee-level vigilance pedal and adjust safety alertness rules to allow reset via either front or knee pedal.

Background The neck, shoulders, and lower back are the primary affected areas of work-related musculoskeletal disorders. In manual tasks, combinations of hand functional height (defined as working height below the waist), awkward postures, and cognitive load are common risk factors. However, there is limited literature documenting how these factors specifically alter biomechanical load on the neck, shoulders, and lower back when working at hand functional height. Objective To explore quantitative differences in biomechanical load on the neck, shoulders, and lower back of workers performing manual tasks at hand functional height under different postures and cognitive load combinations. Methods A 3x2 within-subject design was implemented, with three postures (squat, kneeling, and stoop) and two levels of cognitive load (with cognitive load induced by a 2back task and without cognitive load). Ten male university students were recruited to perform a predetermined assembly task (a sequence of loosening and tightening screws) at hand functional height. Surface electromyography (sEMG) and 3D motion capture system were employed to assess the participants’ trunk biomechanical load in executing the tasks. Additionally, subjective perception, including fatigue, muscle pain, and cognitive load, were evaluated using scales. Results Significant variations in biomechanical load were observed across the three postures (P<0.05). The stoop posture exhibited the lowest muscle activation in most target muscles, except for the sternocleidomastoid, and showed the fastest decline in instantaneous median frequency (IMF) of the erector spinae, with a rate of (-0.050±0.008) Hz per unit time (0.128 s), and the greatest trunk flexion angle (35.14°±4.40°). Performing the task by squatting resulted in the highest muscle activation, especially in the upper trapezius, where maximum voluntary contraction percentage reached 20.07%±1.26%. In addition, the squatting posture also resulted in larger joint angles in the sagittal plane for the neck (−7.03°±2.70°), shoulders (60.20°±7.89°), and lower back (34.42°±4.20°). The kneeling posture showed intermediate muscle activation, the slowest IMF decline for the erector spinae in the lower back (−0.005±0.008) Hz per unit time (0.128s), and the joint angles were closest to neutral. The task performance results were also superior in the kneeling posture. Regarding cognitive load, no significant differences were found for most biomechanical indicators, except for subjective cognitive load scores, neck flexion, and shoulder external rotation angles. Conclusion In assembly tasks performed at hand functional height, kneeling results in moderate biomechanical load on the neck, shoulders, and lower back while also improves task performance compared to squatting and forward bending. Additionally, no significant effects of cognitive load under the 2back condition on biomechanical load are observed.

Background The Belt and Road Initiative is promoting the growth of the cross-border population, and there is still a lack of study on modifiable factors associated with health-related preventive behaviors among resident aliens in China. Public health events may highlight the relevant factors. Objective To conduct a pilot study to preliminarily identify potential modifiable factors associated with preventive behaviors among resident aliens in China, and to explore possible mediating effects of positivity and self-efficacy on the relationship between satisfaction of health services and preventive behaviors, aiming to provide ideas for further research in this direction. Methods A cross-sectional survey was conducted among foreigners in a city of East China by using snowball sampling in July 2023. Based on the protection motivation theory, the Self-Efficacy Scale, Positivity Scale, Preventive Behaviors Scale, and Satisfaction of Health Services Scale were adopted in the survey. Cronbach's α coefficient was used to evaluate scale reliability. A structural equation model was constructed for validity test and path analysis. Maximum likelihood method was used for parameter estimation, and bias-corrected percentile Bootstrap method was used to verify mediating effect. Results A total of 187 resident aliens were approached and 180 of them returned valid questionnaires. The Cronbach's α coefficients of the Self-Efficacy Scale, Positivity Scale, and Preventive Behaviors Scale were 0.904, 0.784, and 0.821, respectively. The M (P₂₅, P₇₅) scores of self-efficacy, positivity, preventive behaviors, and satisfaction of health services were 32 (27, 35), 29 (25, 30), 17 (14, 20), and 4 (3, 5), respectively. Statistically significant differences in the scores of preventive behaviors were identified among the participants by religious belief, geographical location, and economy (P<0.05). The results of path analysis showed that satisfaction of health services, positivity, and self-efficacy had direct positive effects on preventive behaviors (P<0.05), and positivity and self-efficacy played multiple mediation roles in the relationship between satisfaction of health services and preventive behaviors. The results of mediating effect test showed that the indirect effects of the three identified paths mediated by positivity and self-efficacy were statistically significant, and the total size of indirect effect was 0.316 (95%CI: 0.180, 0.466) that accounted for 61.2% of the total effect size. The strongest mediating path was satisfaction of health services→positivity→preventive behaviors, with an indirect effect size of 0.167 (95%CI: 0.046, 0.335) that accounted for 32.4% of the total effect size. Conclusion Future studies and policy formulation on preventive behaviors of foreigners in China should focus on the social demographic factors such as geographical location of home country, religious belief, and cultural customs. At the same time, the study of path relationship of preventive behaviors should embrace environmental factors, emotional factors, and cognitive factors.

Background Occupational stress is an important factor affecting the health of working population, wellness is a topic that has received much attention in recent years, and sleep quality and wellness have a certain impact on occupational stress. Objective To understand the current situation of occupational stress among locomotive engineers in in the Yangtze River Delta, explore the influence of well-being and sleep quality on occupational stress, and provide a theoretical basis for occupational stress intervention among locomotive engineers. Methods Sampling was conducted from October to December 2022 using stratified random sampling. The Chinese version of the Brief Occupational Tension Questionnaire based on the Job Demand-Control Model (JDC model), the World Health Organization 5-item Well-Being Index (WHO-5), and the Pittsburgh Sleep Quality Index (PSQI) scale were used to investigate the occupational stress, well-being, and sleep quality of locomotive engineers. Logistic regression was used to analyze the effects of sleep quality and well-being on occupational stress, and additive and multiplicative interaction models were applied to evaluate the interactive effects of well-being and sleep quality on occupational stress. Results A total of 8243 questionnaires were collected from five locomotive companies, and after excluding unqualified questionnaires, a total of 7976 questionnaires were included in the analysis. The number of locomotive engineers in the Yangtze River Delta reporting positive occupational stress was 4633 (58.09%), the number of low-level well-being was 4949 (62.05%), and the number of poor sleep quality was 4129 (51.77%). The distribution of occupational stress varied by age, length of service, region, technical level, nature of vehicle, education, per capita monthly family income, marital status, smoking, drinking, number of exercise sessions per week, quality of sleep, work shifts, and length of commute (P<0.01). The results of logistic regression showed that a lower level of occupational stress was associated with >11000 yuan per capita monthly household income (OR=0.795, 95%CI: 0.656, 0.964), high level of well-being (OR=0.477, 95%CI: 0.430, 0.528), and good sleep quality (OR=0.588, 95%CI: 0.531, 0.651); a higher level of occupational stress was associated with night shifts: 1 or fewer night shifts (OR=1.707, 95%CI: 1.312, 2.221), 2 to 3 night shifts (OR=2.649, 95%CI: 2.111, 3.325), and 4 or more night shifts (OR=2.804, 95%CI: 2.202, 3.571); a higher level of occupational stress was associated with 60 min or more commuting time (OR=1.353, 95%CI: 1.111, 1.646). Regarding interaction between poor sleep quality and low well-being on occupational stress, the relative excess risk ratio (RERI), attributable risk index (API), and synergy index (SI) were 1.451 (1.059, 1.844), 0.417 (0.327, 0.507), and 2.407 (1.787, 3.241), respectively, and the result of the multiplicative interaction was an OR of 1.546 (95%CI: 1.262, 1.893). Conclusion The prevalence of occupational stress among locomotive engineers in the Yangtze River Delta region is generally at a medium level compared with other industries. Good sleep quality reduces the risk of occupational stress to a greater extent than high well-being, and poor sleep quality and low well-being can interact and further increase the risk of occupational stress.