Design and evaluation of an ergonomic chair for near-ground welding based on muscle activity and usability

Analyzing musculoskeletal risk-severity among small scale casting workers using ergonomic assessment tools: A statistical approach

BACKGROUND: Work-related musculoskeletal disorders (WMSDs) are leading cause of injuries among economically backward workers employed under small scale metal casting units especially in developing countries. In India, most casting unit’s falls under small and medium enterprises having inadequacy of advanced technological equipment’s due to several economic constraints and rely intensively on manual labour. Foundry work is very much prone to WMSDs involving much physical interaction of workers with their jobs which includes several risk factors. OBJECTIVE: The study objectives were to analyse the musculoskeletal risk prevalence among small scale casting workers using ergonomic assessment tools and statistical approach. METHODS: In present study, WMSDs risk prevalence has been examined using Rapid Entire Body Assessment (REBA) and virtual ergonomics. Further, risk evaluations were analysed using Mann–Whitney U test and Taguchi L25 orthogonal array. RESULTS: Results revealed manual handling task as being most vulnerable followed by the fettling section. Statistically significant differences were observed (p-value < 0.05) among all the work-sections except lift-lower task and molding section (p = 0.361; p > 0.05) for left side region; and lift-lower task and fettling section (p = 0.230; p > 0.05) for the right side region, where differences were not statistically significant. ANOVA results indicated that workstation height followed by population percentile and object weight were dominant factors significantly affecting the response parameter i.e. L4-L5 spine compression (p-value < 0.01); however workstation width (p-value > 0.05) had no significant effect. CONCLUSION: The present study may guide foundry industrialists in analysing the mismatch between the workers’ job profile and redesigning existing workstation layouts in small scale foundries based on minimizing the WMSDs risk severity associated with the work tasks.

Reaching in sitting: The effect of seat design and body manipulations

BACKGROUND

Sitting is a common and familiar position used daily as a platform for many motor activities in the workplace, at school, or at home.

OBJECTIVE

To investigate how difference in the chair design and selected sitting manipulations contribute to reach distance in sitting.

METHODS

Ten healthy subjects were required to reach forward as far as possible while sitting in an adjustable chair with 0°, 10° forward or 10° backward inclination of the seat, with and without footrest and leg support, with legs crossed, and when holding the edge of the seat with the contralateral arm.

RESULTS

In comparison to sitting with feet on the footrest, the maximal reaching distance decreased significantly when sitting on either forward or backward inclined seat (p <  0.05) and it increased when the subjects held the edge of the seat while seated with footrest and the posterior leg support (p <  0.05). There was no major effect of crossing the legs or the use of anterior leg support on the maximal reach distance.

CONCLUSIONS

Modification of the chair design could increase or decrease reaching distance in sitting. The outcome of the study provides a background for future investigations of the effect of sitting positions on reaching distance in the workplace, at home, or at school.