Analysis of Physical Workloads and Muscular Strain in Lower Extremities During Walking “Sideways” and “Mixed” Walking in Different Directions in Simulated U-Shape in the Lab

Abstract

The muscular strain at the lower extremities was analysed in the IAD-lab using the simulated U-shape with short-cycle tasks (approx. 80 s.) with walking “sideways” and “mixed” walking (sidesteps and normal steps). Also focus was on analysis of the effects of “walking sideways counter clockwise” vs. “turn clockwise sideways” on the muscular strain in the three selected muscles in the right and the left leg. Four different scenarios were tested. The U-shape consisted of five work stations, was 2 m long and 1.4 m wide in scenarios walking with “sidesteps” (A, B) only. In scenarios with “mixed” walking the assembly U-shape was about 3,2 m long and 1.4 m wide. The EA-activities in selected three leg muscles in the left and right legs were analysed using surface EMG-method. Six test subjects, between 19 and 30 years old, without experience in assembly work took part in the study. The results complement the study Wakula et al. (2017a,b) and show that walking “sideways” counter-clockwise (CC) cause the selected right leg muscles more strain compared to the left leg muscle by some test persons. When walking clockwise (C) two muscles in the left leg were more stressed compared to the right leg muscles. Changing the direction of moving at the U-line: CC $\to$ C $\to$ CC $\to$ C is positive for the muscular strains - it brings some balance of the EA values in analyzed right and left leg muscles. Walking with “mixed” (lateral and two-three normal) steps in the analyzed U-shape did not reduce muscular strains in the legs compared to walking with “sidesteps” only.