Davood Afshari, Niloofar Chinisaz, Maryam Seyedtabib, Iman Dianat, Maryam Nourollahi-Darabad,
Volume 14, Issue 4 (12-2024)
Abstract
Introduction: Biomechanical risk factors, including wrist and elbow angle and standing and sitting position, are the primary factors affecting hand grip strength and perceived exertion. The interaction of these factors can include different effects on grip strength and perceived exertion. Therefore, the present study examines the interaction of varying wrist and elbow angles in sitting and standing postures on the variability of grip strength and perceived exertion.
Material and Methods: In the present study, 30 students (15 females, 15 males) aged 19-30 participated. The average grip strength was measured by a dynamometer for 12 different positions based on the angle of the wrist and elbow in both standing and sitting postures. Perceived exertion was also assessed using the Borg CR-10 scale for each setting. Data analysis was performed using SPSS 23. The Wilcoxon test was applied to compare perceived exertion between standing and sitting postures. Furthermore, a three-way ANOVA was performed to examine interactions between posture (standing/sitting), elbow, and wrist angles. Mauchly’s Sphericity Test was applied to confirm the ANOVA assumptions, and effect sizes for multivariate analysis were calculated (partial η2).
Results: In both sitting and standing postures, the highest average grip strength was observed at a 0-degree wrist angle with a 90-degree elbow angle (standing: 28.6 ± 10.8, sitting 25.8 ± 9.8), while the lowest average grip strength was recorded at full wrist extension with a 0-degree elbow angle (standing: 19.3 ± 6.5, sitting 17.9 ± 6.9). In all three elbow angles examined (0°, 60°, and 90°), the highest value of perceived exertion was recorded in the full extension of the wrist. The changes in the grip strength at different angles were the same for sitting and standing postures, yet the hand grip strength was higher in the standing than the sitting posture (P-value<0.001). The effect of each of the studied factors (sitting and standing postures, wrist angle, and elbow angle) alone on hand grip strength and perceived exertion was deemed to be significant (P-value<0.001). Regarding the two-way interactions of the research variables, the interaction effect of elbow and wrist angles on grip strength (partial η2=0.09, P-value=0.015) and perceived exertion was significant (partial η2=0.08, P-value=0.06). Furthermore, findings indicated that the wrist angle had a more pronounced effect on the value of the perceived exertion (partial η2=0.31, P-value<0.001).
Abouzar Amirian, Davood Afshari, Leila Omidi, Maryam Seyedtabib, Maryam Nourollahi-Darabad,
Volume 15, Issue 2 (7-2025)
Abstract
Introduction: Nowadays, in order to improve the level of Health, Safety and Environment (HSE) culture of employees, organizations have reached this important conclusion that the weaknesses and strengths of the system should be identified by periodically evaluating the level of HSE culture. On the other hand, Although the social exchange relationships between employers and employees are increasingly important to the performance of safety management systems, the interaction between psychological aspects, workplace safety and its relationship with employees’ HSE citizenship behavior have been less studied. The aim of the present study was to investigate the effect of psychological contract of HSE on the relationship between HSE culture and HSE citizenship behavior among employees in a steel manufacturing industry.
Material and Methods: In the present study, three questionnaires: Psychological contract of HSE, HSE citizenship behavior and HSE culture were used; the reliability and validity of these questionnaires approved in past studies. The questionnaires were randomly distributed to 434 employees of a steel industry. In order to model structural equations, Smart PLS software was used, the reliability and validity of the models were investigated.
Results: The results of the study showed that HSE culture is a significant predictor of HSE citizenship behavior (P-value<0.001). HSE culture has a positive and significant effect on psychological contract (P-value <0.001), and psychological contract has a mediating role in the relationship between HSE culture and HSE citizenship behavior.
Conclusion: The results of the present study showed that HSE culture and psychological contract directly affect HSE citizenship behavior. Also, based on the findings of this study, HSE culture, in addition to directly affecting HSE citizenship behavior, can also affect HSE citizenship behavior by affecting psychological contract as a mediating variable.
