Publication date: Available online 31 December 2018
Source: Journal of Biomechanics
Author(s): Michael Ernst, Martin Götze, Reinhard Blickhan, Roy Müller
Abstract
In running, humans use different control strategies that are most likely influenced by environmental conditions. For example, when human runners face a change in ground level, they adapt the height of their center of mass (CoM) in preparation. In a situation in which a drop might occur but without visual cues regarding its actual height, such a preparation is not possible. We here used camouflaged drops (which occurred by chance) as mechanical disturbances and analyzed the adaptations in the vertical oscillation of the runners CoM. We found that humans lowered their CoM by about 25 % of the possible drop height in preparation for the camouflaged contact, regardless of whether a drop occurred or not. In flight phase following the disturbance, the CoM was lowered by about 90 % of the drop height in the case of the camouflaged drop and remained almost unaffected (+5 %) in the case of level ground. Thus, runners resort to a CoM-control strategy with a fixed desired trajectory height in the flight phase following the camouflaged ground contact. In contrast to previously reported results which show that visible ground level changes were compensated within several steps, this strategy compensates ground level disturbances instantly within a single step.
from ! Human Diseases via Alexandros G.Sfakianakis on Inoreader http://bit.ly/2AoFYrQ
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