The Impact of Ergonomically Designed Workstations on Shoulder EMG Activity during Carpet Weaving

Video analysis of biomechanical risk factors for musculoskeletal disorders in loincloths female weavers Faso Dan Fani in Burkina Faso

Background

The purpose of this study is to describe the kinematic characteristics of manual weaving related to the biomechanical risk factors for musculoskeletal disorders.

Methods

Twelve professional female weavers participated in this study. The video recording of their workstations was performed perpendicularly in the sagittal and transverse planes in a synchronized manner, at about 2.45 m and for 5 minutes. The videos were then analyzed using the Kinove software. Statistical processing by the statistical SPSS 22 software.

Results

The results identified a succession of cycles, each with two important phases called the "interlacing" phase and the "winding/adjustment" phase. The average cycle time is 127.9 ± 11.7 seconds. The "interlacing" phase is the longest and concerns an average 80% of the cycle time or 103.5 ± 35.9 seconds. The segmental movements are mainly flexion-extension type with angular variations constantly above the acceptable limits. It is the same for the repetitiveness of the movements which solicit the upper limb and the trunk particularly.

Conclusions

These results recommend one of the actions to prevent musculoskeletal disorders including instructions on postures and frequencies of weaving movements as well as physical exercises adapted to the physical needs of practitioners.

Determination of reference ranges for normal upper trapezius elasticity during different shoulder abduction using shear wave elastography: a preliminary study

The purpose of this study was to determine the reference ranges of normal upper trapezius (UT) elasticity during different shoulder abduction using shear wave elastography (SWE). Mean shear wave velocity (SWV) of UT elasticity in eighty healthy participants were measured at left and right shoulder 0° abduction and 90° passive abduction (L0°, R0°, L90°, R90°) with SWE. The effects of potential factors (gender, UT thickness, age, and body mass index) on UT elasticity were analyzed. The reference ranges of normal UT elasticity were calculated by using the normal distribution method. UT elasticity was significantly different among various shoulder abduction (P < 0.0001). UT elasticity was significantly higher in males at both L90° (P < 0.05) and R90° (P < 0.01) than in females. The reference ranges of normal UT elasticity were 2.90-4.01 m/s at L0° and 3.01-4.29 m/s at R0°, and were 4.90-6.40 m/s in males and 4.40-6.20 m/s in females at L90°, 5.20-7.02 m/s in males and 4.71-6.80 m/s in females at R90°. Our results suggest that gender should be considered when determining the reference ranges of normal UT elasticity at L90° and R90° with SWE. These values may provide quantitative baseline measurements for the assessment of UT muscle strain in the future.