title: Planar covariation of limb elevation angles during bipedal locomotion in common quails (Coturnix coturnix).
abstract: In human bipedal walking, temporal changes in the elevation angle of the thigh, shank and foot segments covary to form a regular loop within a single plane in three-dimensional space. In this study, we quantified the planar covariation of limb elevation angles during bipedal locomotion in common quails to test whether the degree of planarity and the orientation of the covariance plane differ between birds, humans and Japanese macaques as reported in published accounts. Five quails locomoted on a treadmill and were recorded by a lateral X-ray fluoroscopy. The elevation angle of the thigh, shank and foot segments relative to the vertical axis was calculated and compared with published data on human and macaque bipedal locomotion. The results showed that the planar covariation applied to quail bipedal locomotion and planarity was stronger in quails than in humans. The orientation of the covariation plane in quails differed from that in humans, and was more similar to the orientation of the covariation plane in macaques. Although human walking is characterized by vaulting mechanics of the body center of mass, quails and macaques utilize spring-like running mechanics even though the duty factor is >0.5. Therefore, differences in the stance leg mechanics between quails and humans may underlie the difference in the orientation of the covariation plane. The planar covariation of inter-segmental coordination has evolved independently in both avian and human locomotion, despite the different mechanical constraints.
authors.affiliation: Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan ogihara@mech.keio.ac.jp.
authors.forename: Naomichi
authors.initials: N
authors.lastname: Ogihara
authors.affiliation: Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Oku
authors.affiliation: Science of Motion, Institut für Sportwissenschaft, Friedrich-Schiller-Universität Jena, 07749 Jena, Germany.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Andrada
authors.affiliation: Science of Motion, Institut für Sportwissenschaft, Friedrich-Schiller-Universität Jena, 07749 Jena, Germany.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Blickhan
authors.affiliation: Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany.
authors.forename: John A
authors.initials: JA
authors.lastname: Nyakatura
authors.affiliation: Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany.
authors.forename: Martin S
authors.initials: MS
authors.lastname: Fischer
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003370:Coturnix; D007596:Joints / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology*; D016138:Walking / Q000502:physiology*
keywords: Grounded running; Human; Inter-segmental coordination; Kinematics; Macaque