Positioning of pivot points in quadrupedal locomotion: limbs global dynamics in four different dog breeds

Emanuel Andrada; Gregor Hildebrandt; Hartmut Witte; Martin S Fischer

doi:10.3389/fbioe.2023.1193177

Positioning of pivot points in quadrupedal locomotion: limbs global dynamics in four different dog breeds

Front Bioeng Biotechnol. 2023 Jul 7:11:1193177. doi: 10.3389/fbioe.2023.1193177. eCollection 2023.

Authors

Emanuel Andrada^{1

2}, Gregor Hildebrandt^{1

2}, Hartmut Witte², Martin S Fischer¹

Affiliations

¹ Institute of Zoology and Evolutionary Research, Friedrich-Schiller-University Jena, Jena, Germany.
² Group of Biomechatronics, Institute of Mechatronic System Integration, Technische Universität Ilmenau, Ilmenau, Germany.

Abstract

Dogs (Canis familiaris) prefer the walk at lower speeds and the more economical trot at speeds ranging from 0.5 Fr up to 3 Fr. Important works have helped to understand these gaits at the levels of the center of mass, joint mechanics, and muscular control. However, less is known about the global dynamics for limbs and if these are gait or breed-specific. For walk and trot, we analyzed dogs' global dynamics, based on motion capture and single leg kinetic data, recorded from treadmill locomotion of French Bulldog (N = 4), Whippet (N = 5), Malinois (N = 4), and Beagle (N = 5). Dogs' pelvic and thoracic axial leg functions combined compliance with leg lengthening. Thoracic limbs were stiffer than the pelvic limbs and absorbed energy in the scapulothoracic joint. Dogs' ground reaction forces (GRF) formed two virtual pivot points (VPP) during walk and trot each. One emerged for the thoracic (fore) limbs (VPP_TL) and is roughly located above and caudally to the scapulothoracic joint. The second is located roughly above and cranially to the hip joint (VPP_PL). The positions of VPPs and the patterns of the limbs' axial and tangential projections of the GRF were gaits but not always breeds-related. When they existed, breed-related changes were mainly exposed by the French Bulldog. During trot, positions of the VPPs tended to be closer to the hip joint or the scapulothoracic joint, and variability between and within breeds lessened compared to walk. In some dogs, VPP_PL was located below the pelvis during trot. Further analyses revealed that leg length and not breed may better explain differences in the vertical position of VPP_TL or the horizontal position of VPP_PL. The vertical position of VPP_PL was only influenced by gait, while the horizontal position of VPP_TL was not breed or gait-related. Accordingly, torque profiles in the scapulothoracic joint were likely between breeds while hip torque profiles were size-related. In dogs, gait and leg length are likely the main VPPs positions' predictors. Thus, variations of VPP positions may follow a reduction of limb work. Stability issues need to be addressed in further studies.

Keywords: VPP-control; dog breed; dog locomotion; effective legs; leg dynamics.

Grants and funding

The study was supported by Biologische Heilmittel Heel GmbH. This work was also supported by DFG FI 410/16-1 as part of the NSF/CIHR/DFG/FRQ/UKRI-MRC Next-Generation Networks for Neuroscience Program. We acknowledge support by the German Research Foundation Project-No. 512648189 and the Open Access Publication Fund of the Thueringer Universitaets- und Landesbibliothek Jena.