Purpose: Many forestry workers who use chain-saws suffer from low back pain. Previous studies have reported that low back pain is related to the working postures while felling a tree with a using chain-saws. However, no previous study has investigated trunk muscle activities during work. The purpose of this study was to clarify the relationship between working postures while holding a chain-saw, and trunk muscles activities as measured by surface electromyography (EMG). Method: Subjects were 10 males who were not forestry workers. Four task postures while holding a chain-saw were tested: standing, 30^o trunk flexion, 90^o trunk flexion and half-kneeling. EMG recordings were obtained bilaterally of the lumbar paraspinal (LP) muscles and rectus abdominis (RA) muscles. Raw EMG data were processed by integrating the EMG and normalizing them to %MVC. The paired t-test was used to detect statistical differences in the activities between the right and left LP muscles and RA muscles. One-factor repeated measures ANOVA was used to compare the bilateral LP and RA muscle activities among the 4 different postures. The significance level was set to less than 5%. Results: In the half-kneeling posture, the right LP muscle activity was 14.7% higher than the left LP muscle activity (p<0.05); however, there were no significant differences in muscle activities among the other postures. The right LP muscle activity of 30^o trunk flexion posture was 25.6% higher than that of the standing posture, and 14.2% higher than that of half-kneeling posture (p<0.05). The bilateral LP muscle activities of the 90^o trunk flexion posture were the highest of the 4 postures, 16.7% higher than the half-kneeling posture (p<0.05) right LP muscle activity. There was a tendency of increase in the left LP muscle activity when trunk flexion angle increased, but no significant differences among the 4 postures were found. The bilateral RA muscle activities were low and did not significantly differ among the 4 postures. Conclusions: This study showed that when the trunk is flexed, the LP muscle activities change asymmetrically, with the right LP muscle activity increasing significantly compared to the standing posture and the half-kneeing posture, but there was no significant difference in the left LP muscle activity. These results suggest that working postures that involve trunk flexion while felling a tree with a holding chain-saw may lead to increased loading of the LP muscles.

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Objective: The purpose of this study was to examine the support activities provided for occupational health nurses aimed at improving psychosocial working environments, related knowledge and skills, and learning environments as well as associations among these factors. In addition, we aimed to create correlated factor models to describe the support activities in order to identify ways to promote these activities among occupational health nurses. Methods: An anonymous mail-based questionnaire survey was conducted of occupational health nurses who were members of the Japan Society for Occupational Health and belonged to enterprises or independent health insurance societies. Among 356 returned questionnaires (response rate: 46.4%), all the main items were answered in 329 (valid response rate: 92.4%), and these questionnaires were analyzed. Factor analysis was performed for the seven items pertaining to support activities for the improvement of psychosocial working environments and models of each factor of the support activities were developed using covariance structure analysis. Results: In the factor analysis, [Clarifying a stress-related situation and providing advice] and [Facilitating workplace involvement] were identified as support-related factors. The mean implementation rates for these approaches were approximately 50 to 80%, and less than 40%, respectively. [Clarifying a stress-related situation and providing advice] was associated with skills of “providing superiors with explanations to enhance their understanding” and “collecting and analyzing stress survey results by department”, and knowledge of “personal stress questionnaires” and “common stress factors in working environments”. The above-mentioned knowledge and skills were associated with self-learning of “examining and reporting daily activities for the improvement of working environments” and “reviewing related papers”. [Facilitating workplace involvement] was associated with skills of “indirectly supporting discussions led by key persons in working environments” and “giving feedback regarding occupational stress survey results to superiors”, and knowledge of “tools for the improvement of working environments” and “appropriate methods to use stress questionnaires”. In addition, such knowledge and skills were associated with self-learning and learning environments of “participating in seminars to learn effective methods to use group-work approaches” and “receiving support and advice from mentors of universities and research institutions”. Discussion: The features of occupational health nurse support for the improvement of psychosocial working environments were revealed by this study. The implementation rates suggest that it is particularly necessary to promote [Facilitating workplace involvement]. It will be necessary to encourage the acquisition of associated knowledge and skills in order to promote occupational health nurse support for the improvement of psychosocial working environments.

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Objectives:Mental disorders are increasing and their influence on productivity is a concern in the workplace. However, few studies have investigated depression among blue-collar and white-collar workers in the manufacturing industry. The purpose of this study was to clarify the factors associated with depressive symptoms, focusing on lifestyles and insomnia. Methods:A self-administered questionnaire survey was conducted of 1,963 workers at an annual health checkup in a manufacturing company. Of the 1,712 respondents (response rate: 87%), 1,258 male worker subjects (blue-collar 674; white-collar 584) were analyzed after excluding those with mental diseases. The questionnaire included items on basic attributes and lifestyle. The Athens Insomnia Scale (AIS) and The Center for Epidemiologic Studies for Depression Scale (CES-D) were used to evaluate insomnia and depressive symptoms. Results:The incidence of depressive symptoms with CES-D scores of ≥16 was 15.1% in both the blue-collar and the white-collar workers. Insomnia with AIS scores of ≥6 were encountered in 18.8% of the blue-collar workers and 18.3% of the white-collar workers. Multiple logistic regression analyses showed that for the blue-collar workers, depressive symptoms were associated with “AIS scores ≥6” (Odds ratio (OR): 10.93; 95% confidence interval (CI): 6.12–19.15), “not get rid of fatigue with sleep” (OR: 3.36; 95%CI: 1.85–6.09), “skip breakfast over 3 times a week” (OR: 3.10; 95%CI:1.42–6.76), “no family living together” (OR: 2.08; 95%CI: 1.05–4.12), and “commuting time” (OR: 1.01; 95%CI: 1.00–1.02). For the white-collar workers, depressive symptoms were related to “AIS scores ≥6” (OR: 14.91; 95%CI: 7.54–29.49), and “no family living together” (OR: 2.54; 95%CI: 1.27–5.09). Sleep time was not associated with depression in both blue- and white-collar workers. Depressive symptoms were found in 51.6% of the blue-collar workers with insomnia with AIS scores ≥6 and 53.8% of white-collar workers. Conclusions: Depressive symptoms were found at the same prevalence rate in both blue-collar and white-collar workers, which suggests that health measures for depression are necessary for both types of worker. Depressive symptoms were significantly associated with insomnia. Health advice focusing on insomnia as well as lifestyle may be important for workers.

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