Hand Muscle Response to Diverse Tailoring Scissor Types: A Biomechanical and EMG Assessment

Abstract

The habitual usage of Manual Fabric Scissors (MFS) causes traumatic hand injuries in a large population of less represented workers in informal work-system. However, there is dearth of information on the biomechanical stresses of the fingers attributable to usage of Straight-cut MFS. Therefore, simulated field observations were explored for better understanding of hand muscular response of habitual MFS users. Surface Electromyography was used for collecting data on some four hand muscles from a convenient sample size of twenty-four participants. Data was also collected for the four different scissors designs used in the twenty-four different tasks performed by each participant. The participants (age 25.58 ±3.62years; height 167.88 ±9.13cm; weight 74.25 ±17.14 kg) performed randomized twenty-four cutting tasks of four scissors designs (S1-S4), three table heights (H1-H3) and two different fabrics (F1-F2). Matlab was used for data analysis and ANOVA at α0.01 showed significant differences in the muscular response to scissors design’s workload.  Small, closed-handle scissors designs placed higher demand on users leading to higher risk of contusions, while wide-handle scissors generated lower muscular activities with better user performance. Ergonomic considerations in MFS handle design would mitigate hand injuries in frequent users because optimal handle design enhances grip force and grip strength varies with handle size. Practitioner summary: This study gives the simulated feedback from habitual users whose health protection need should guide scissors design. Its input to intellectual knowledge and benefits to human society at large is useful for both the manufacturers and the end users of manual fabric scissors.