Gait Characteristics When Walking on Different Slippery Walkways

Objective
: This study sought to determine the changes in muscle activity about the ankle, knee, and hip in able-bodied people walking at steady state on surfaces with different degrees of slipperiness.
Methods
: Muscle activity was measured through electromyographic signals from selected lower limb muscles and quantified to directly compare changes across surface conditions.
Results
: Our results showed distinct changes in the patterns of muscle activity controlling each joint. Muscles controlling the ankle showed a significant reduction in activity as the surface became more slippery, presumably resulting in a compliant distal joint to facilitate full contact with the surface. Select muscles about the knee and hip showed a significant increase in activity as the surface became more slippery. This resulted in increased knee and hip flexion likely contributing to a lowering of the body's center of mass and stabilization of the proximal leg and trunk.
Conclusion
: These findings suggest a proximal-distal gradient in the control of muscle activity that could inform the future design of adaptable prosthetic controllers.
Significance
: Walking on a slippery surface is extremely difficult, especially for individuals with lower limb amputations because current prostheses do not allow the compensatory changes in lower limb dynamics that occur involuntarily in unimpaired subjects. With recent advances in prosthetic control, there is the potential to provide some of these compensatory changes; however, we first need to understand how able-bodied individuals modulate their gait under these challenging conditions.