Gait stability and muscle activity at the upper trapezius and lower erector spinae muscles while walking with backpack loads

This chapter seeks to explore the mechanisms of gait stability and muscle activity at the upper and lower back while walking with backpack loads. Backpack loads raise the combined centre-of-mass (COM) of the backpack and body superiorly and induce gait instability. The central nervous system uses various mechanisms to compensate for this instability. In our study we found an increase in the double support time, the forward lean of the trunk and a reduction in the walking speed, while walking with backpack loads to counter for the induced instability. We also found that for loads higher than 15% of bodyweight (BW), backpack loads should not be concentrated on the lower part of the back as they induce higher changes in gait parameters compared to normal walking without backpacks. We did not find any significant differences in the back muscle activity between the three different load conditions of 10, 15 and 20% BW load