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Logo for the Journal of Rehab R&D
Volume 42 Number 3, May/June 2005
Pages 381 — 390

Abstract - Effects of adding weight to the torso on roll-over characteristics of walking


Andrew H. Hansen, PhD;1* Dudley S. Childress, PhD1-3

1Rehabilitation Engineering Research Program, Department of Physical Medicine and Rehabilitation, Northwestern University Feinberg School of Medicine, Chicago, IL; 2Jesse Brown VA Medical Center, Chicago, IL; 3Department of Biomedical Engineering, McCormick School of Engineering and Applied Science, Northwestern University, Evanston, IL
Abstract — Ten participants without physical impairment walked with 0 kg, 11.5 kg, and 23.0 kg of added weight equally distributed about the torso in a harness. At each weight level, the participants walked at slow, normal, and fast self-selected walking speeds. We examined the roll-over characteristics by determining the ankle-foot and knee-ankle-foot roll-over shapes. These shapes, which are the effective rockers created by the respective lower-limb systems between heel contact and opposite heel contact of walking, are found if one transforms the center of pressure of ground reaction force into body coordinate systems. The roll-over shapes of the ankle-foot and knee-ankle-foot systems did not change appreciably with added weight at any of the three walking speeds. The invariance of these biologic systems to added weight should be considered when prostheses and orthoses are designed that intend to replace and augment their function in walking.
Key words: ankle, foot, gait, human movement, knee, orthotics, prosthetics, rockers, roll-over shapes, weighted walking.

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