Iranian Journal of Ergonomics

Introduction: Manual load lifting is the most common and most stressful activity in manual handling of loads that imposes the highest possible amount of biomechanical pressure on the body, particularly on the spine. The present study was conducted to determine the prevalence of musculoskeletal disorders and to estimate the mechanical force exerted on the lower back in workers responsible for manual load lifting.

Material and Methods: The present cross-sectional study was conducted on 120 workers responsible for manual load lifting activities in 7 industrial settings in the city of Shiraz. The Nordic Musculoskeletal Questionnaire (NMQ) was used for determining the prevalence of musculoskeletal disorders and the 3DSSPP software was used to estimate the forces exerted on the lower back during load lifting. Data were then analyzed in SPSS-19.Findings: The results showed that lower back problems constitute the most prevalent musculoskeletal disorder (68.3%). Evaluations conducted in 3DSSPP showed that in 17.5% of the cases, compressive forces, and in 10.8% of the cases, shearing forces exerted on the L5-S1 disc were higher in the workers than the permissible levels. There were no significant differences between the rate of the prevalence of lower back pain at different levels of compressive and shearing forces exerted on the disc (p>0/05).

Results: This finding might indicate the limitations of the method used in this study for conducting a comprehensive assessment of loads exerted on the spine.

Conclusion: The prevalence of musculoskeletal disorders, in particular lower back pain, was estimated to be high among the subjects studied. The risk levels of compressive and shearing forces exceeded the permissible amount in a low percentage of the workers studied. The 3DSSPP software might have certain limitations in the assessment of the pressure exerted on the spine.

Introduction: Perceived work-related fatigue is an important issue since it may adversely impact workers’ performance. Additionally, workers’ fatigue is known as a main cause of occupational accidents in workplaces. Considering the consequences of perceived work-related fatigue, assessing fatigue at workplace is critical to work-related fatigue risk management. Therefore, this study assessed the validity and reliability of the Persian version of the Swedish Occupational Fatigue Inventory (SOFI-20) among Iranian employees.

Materials and Methods: In this cross-sectional study, 501 employees of two petrochemical companies were selected by simple sampling method. The Persian version of SOFI-20 was developed using forward and backward translation processes and used to collect the required data. The validity and reliability of the translated inventory were examined by confirmatory factor analysis (CFA) and Cronbach’s alpha coefficient, respectively.

Results: Assuming that some items of the Persian version of the SOFI-20 were correlated, the confirmatory factor analysis was repeated to achieve better fitness. The results of CFA revealed an acceptable fit for the Persian version of SOFI-20. The total Cronbach’s Alpha coefficient for the SOFI-20 was 0.95. Cronbach’s alpha coefficients for different dimensions of the SOFI-20 were found to range from 0.690 to 0.887.

Conclusion: The validity and reliability of the Persian version of the SOFI-20 was acceptable for assessing the dimensions of work-related fatigue among Iranian employees.

Introduction: Sleep disorder is very common among employees and is considered as one of the crucial health problems. Sleep disorders have a negative impact on job performance. The present study was regarding the relationship of sleep quality, sleepiness and sickness absence.

Methods: This cross-sectional study was conducted on 400 employees of a gas company through random sampling. The study data were collected using the Pittsburg Sleep Quality Index (PSQI) and the Karolinska Sleepiness Scale (KSS). Mann-Whitney U test and Spearman’s correlation coefficient were applied for data analysis.

Results: While 43.2% of the participants enjoyed satisfactory sleep quality, 56.8% had unsatisfactory sleep quality. Statistical tests indicated a significant difference in sickness absence of the personnel with good and poor sleep qualities (P = 0.0001). Spearman’s correlation coefficient (ρ = 0.777) indicated a statistically significant correlation between sleepiness index and sickness absence (P = 0.0001).

Conclusions: The results showed a strong positive correlation in sleep quality, sleepiness index of the personnel and sickness absence; i.e. along with decline in sleep quality and incline in sleepiness, the personnel’s sickness absence increased.