Low back pain (LBP) can affect performance in the combined task (CT) of gait and prehension, since it increases muscle activity amplitude during voluntary movements, impairs the anticipatory postural adjustments and reduces gait speed. We analyzed and compared the effect of adding the prehension movement toward a dowel located at three different heights (80, 100 and 120% of the lower limb length) on gait of individuals with and without LBP. The CT caused anticipatory adjustments, showing that gait changes started during the approach phase and continued on the step corresponding to grasping, especially for the lowest dowel height. Furthermore, individuals with LBP reduced walking speed, increased the width of the base of support, increased electromyography activity of low back trunk muscles, and increased the margin of dynamic stability compared with control group. These results suggest that individuals with LBP used a strategy to reduce threat to body stability due to addition of the manual task.
Keywords: chronic low back pain; dynamic stability; gait control; prehension.