ABSTRACT
BACKGROUND: In spite of the increasing degree of automation in industry, manual material handling (MMH) is still performed in many occupational settings. The aim of the current study was to determine the maximum acceptable weight of lift using psychophysical and electromyography indices. METHODS: This experimental study was conducted among 15 male students recruited from Tehran University of Medical Sciences. Each participant performed 18 different lifting tasks which involved three lifting frequencies, three lifting heights and two box sizes. Each set of experiments was conducted during the 20 min work period using free-style lifting technique and subjective as well as objective assessment methodologies. SPSS version 18 software was used for descriptive and analytical analyses by Friedman, Wilcoxon and Spearman correlation techniques. RESULTS: The results demonstrated that muscle activity increased with increasing frequency, height of lift and box size (P<0.05). Meanwhile, MAWLs obtained in this study are lower than those in Snook table (P<0.05). In this study, the level of muscle activity in percent MVC in relation to the erector spine muscles in L3 and T9 regions as well as left and right abdominal external oblique muscles were at 38.89%, 27.78%, 11.11% and 5.55% in terms of muscle activity is more than 70% MVC, respectively. The results of Wilcoxon test revealed that for both small and large boxes under all conditions, significant differences were detected between the beginning and end of the test values for MPF of erector spine in L3 and T9 regions, and left and right abdominal external oblique muscles (P<0.05). The results of Spearman correlation test showed that there was a significant relation between the MAWL, RMS and MPF of the muscles in all test conditions (P<0.05). CONCLUSION: Based on the results of this study, it was concluded if muscle activity is more than 70% of MVC, the values of Snook tables should be revisited. Furthermore, the biomechanical perspective should receive special attention in determining the standards for MMH.
ABSTRACT
BACKGOUND: Work ability is an important issue from a social point of view, as it is essential for workers health and welfare. OBJECTIVE: This study aimed to determine work ability among healthcare personnel and to investigate its relationship with demographic and lifestyle-related factors. METHODS: Data were collected using the Work Ability Index (WAI) questionnaire among 517 personnel of a hospital in Tehran, Iran. RSULTS: Findings showed a mean WAI of 40.3 (±5.2) for the study population. Work ability was significantly lower in the older personnel and higher for men. A significant correlation was observed between BMI and exercise activity and WAI score. Moreover, employees with experience of less than five years had significant higher work ability than those with 16-20 years of service. CONCLUSIONS: Considering the young study population, it seems the mean WAI is not as desirable. The use of lifestyle promoting programs, besides workplace interventions, can be an effective strategy to increase work ability among healthcare workers.
