Trunk deformation in the trotting horse.
Abstract: Estimates of the position of the centres of mass (CM) of body segments are usually extrapolated relative to bony landmarks as determined in cadaver studies. This extrapolation assumes that segments are rigid bodies. Since the trunk represents a large percentage of the total body mass in horses, violation of the rigid body assumption by the trunk segment has important consequences for studying the biomechanics of equine locomotion. Objective: To assess the magnitude of error in CM position due to deformability of the trunk segment and the timing of these errors during the trotting stride. The hypothesis was that shape changes during a stride are repeatable and predictable. Methods: Forty skin markers were attached in a grid pattern on the trunks of 6 adult horses, with an additional marker attached to each hoof. The markers were tracked using an 8 camera motion analysis system. Each horse was tested at 10 different velocities during trotting. The CM of the trunk was calculated under the assumption of a rigid body, based on 5 spine markers and from the volume encompassed by the 40 markers. The difference between the 2 calculation methods quantifies the effect of trunk deformation on the position of the CM. Results: The trunk changed shape during locomotion in a repeatable manner resulting in cyclic changes in CM position. Amplitudes of the CM displacement due to trunk deformation were equal in magnitude in the transverse and longitudinal directions. In the vertical direction, the CM moved only at half the amplitude. Magnitudes were strongly horse-dependent. Conclusions: Shape changes in the equine trunk segment in the horizontal plane should be taken into account when modelling locomotion of horses. Amplitudes are horse dependent, complicating the development of correction routines.
Publication Date: 2009-05-28 PubMed ID: 19469221DOI: 10.2746/042516409x393194Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research investigates the impact of the horse’s trunk deformation on the calculation of the center of mass (CM) during trotting, emphasizing the importance of taking this into account for accurate locomotion modelling in horses.
Objective and Hypothesis
The objective of this study was to analyze the magnitude of error in the position of the center of mass (CM) due to the flexibility of the horse’s trunk during trotting. The study also attempted to analyze the timing of these errors in the trotting stride. The hypothesis indicated that changes in the horse’s shape during a stride are consistent and predictable.
Research Methodology
- A total of forty skin markers were adhered in a grid pattern on the trunks of six adult horses with an additional marker attached to each hoof.
- An eight-camera motion analysis system tracked these markers to study the movement and deformation of the trunk.
- Each horse was tested at ten different velocities during trotting.
- The researchers calculated the center of mass (CM) of the trunk considering it to be a rigid body, using five spine markers. This was then compared to the center of mass calculated using the volume represented by the forty markers to understand the impact of the trunk’s deformation on the CM’s position.
Results
- The results showed a repeatable change in the shape of the horse’s trunk during locomotion causing cyclical changes in the CM’s position.
- The shift in the CM due to the deformation of the trunk was found to be equal in the transverse and longitudinal directions.
- In the vertical direction, the CM’s movement was only at half of the amplitude.
- These shifts were strongly dependent on the individual horse implying varying levels of trunk deformabilities across subjects.
Conclusions
The study concludes that changes in the shape of a horse’s trunk should not be overlooked while modeling the locomotion of horses. However, these changes occur at different magnitudes with different horses complicating the development of correction routines.
Cite This Article
APA
Nauwelaerts S, Clayton HM.
(2009).
Trunk deformation in the trotting horse.
Equine Vet J, 41(3), 203-206.
https://doi.org/10.2746/042516409x393194 Publication
Researcher Affiliations
- Mary Anne McPhail Equine Performance Center, Department of Large Animal Clinical Sciences, D202 Veterinary Medical Center, East Lansing, Michigan 48824-1314, USA.
MeSH Terms
- Animals
- Biomechanical Phenomena
- Energy Metabolism
- Gait / physiology
- Horses / anatomy & histology
- Horses / physiology
- Video Recording
Citations
This article has been cited 2 times.- Hobbs SJ, Bertram JE, Clayton HM. An exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in trotting horses. PeerJ 2016;4:e2190.
- Webb AA, Kerr B, Neville T, Ngan S, Assem H. Kinematics and ground reaction force determination: a demonstration quantifying locomotor abilities of young adult, middle-aged, and geriatric rats. J Vis Exp 2011 Feb 22;(48).
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