Increasing trunk flexion transforms human leg function into that of birds despite different leg morphology

Journal article


AminiAghdam, S., Rode, C., Muller, R. and Blickhan, R. (2017). Increasing trunk flexion transforms human leg function into that of birds despite different leg morphology. Journal of Experimental Biology. 220 (3), pp. 478-486.
AuthorsAminiAghdam, S., Rode, C., Muller, R. and Blickhan, R.
Abstract

© 2017. Published by The Company of Biologists Ltd. Pronograde trunk orientation in small birds causes prominent intra-limb asymmetries in the leg function. As yet, it is not clear whether these asymmetries induced by the trunk reflect general constraints on the leg function regardless of the specific leg architecture or size of the species. To address this, we instructed 12 human volunteerstowalk at a self-selected velocity with four postures: regular erect, or with 30 deg, 50 deg and maximal trunk flexion. In addition, we simulated the axial leg force (along the line connecting hip and centre of pressure) using two simple models: spring and damper in series, and parallel spring and damper. Astrunk flexion increases, lower limb joints become more flexed during stance. Similar to birds, the associated posterior shift of the hip relative to the centre of mass leads to a shorter leg at toe-off than at touchdown, and to a filatter angle of attack and a steeper leg angle at toe-off. Furthermore, walking with maximal trunk flexion induces right-skewed vertical and horizontal ground reaction force profiles comparable to those in birds. Interestingly, the spring and damper in series model provides a superior prediction of the axial leg force across trunk-flexed gaits compared with the parallel spring and damper model; in regular erect gait, the damper does not substantially improve the reproduction of the human axial leg force. In conclusion, mimicking the pronograde locomotion of birds by bending the trunk forward in humans causes a leg function similar to that of birds despite the different morphology of the segmented legs.

Year2017
JournalJournal of Experimental Biology
Journal citation220 (3), pp. 478-486
PublisherThe Company of Biologists
ISSN0022-0949
Digital Object Identifier (DOI)doi:10.1242/jeb.148312
Publication dates
Print01 Feb 2017
Online25 Nov 2016
Publication process dates
Accepted17 Nov 2016
Deposited04 Nov 2019
Publisher's version
License
All rights reserved
File Access Level
Open
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https://openresearch.lsbu.ac.uk/item/885x3

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