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Title: The control and coordination of human stepping
Author: Bancroft, Matthew James
ISNI:       0000 0004 7228 9181
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2018
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Walking is a simple task for most humans. However, the act of lifting a foot from the ground to take a step, as when walking, destabilises the body and threatens a loss of balance. This thesis details a series of studies designed to investigate the control and coordination of a step. In each experiment, the body was voluntarily translated from stationary to the location of a visually-presented target. It is first shown that the movement of the body before a step is modulated by the future location of the foot, even when the location of a step target is made to change unexpectedly before the stepping foot lifts. This pre-step movement provides the body with an initial position and velocity at the start of a step from which it begins to fall under gravity. It is then demonstrated that the movement of the body during the step is largely determined by its initial conditions and the influence of gravity. However, the trajectory of the body is also modified by mid-step ankle torques, which seem particularly important in controlling forwards motion. Next, it is shown that the movement of both the body and leg during a step is variable between steps to the same location. This variability is organised to reduce foot placement error, demonstrating that the body and leg are precisely coordinated to land the foot accurately on its intended target. Surprisingly, this was still the case when visual feedback was denied during the step. Finally, the coordination of a step is investigated in subjects with a genetically determined and pure form of cerebellar degeneration. Foot placement error was increased in subjects with cerebellar dysfunction, with the results suggesting that this originated from both impaired coordination and increased variability in the body and leg movements used during a step.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available