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An exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in trotting horses.

Hobbs SJ, Bertram JE, Clayton HM - PeerJ (2016)

Bottom Line: Discussion.The results indicate that at moderate speeds individual horses use dissociation patterns that allow them to maintain trunk pitch stability through management of the cranio-caudal location of the COP.During the hoof-ground collisions, reduced mechanical energy losses were found in hind-first dissociations compared to fully synchronous contacts.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Applied Sport and Exercise Sciences, University of Central Lancashire , Preston , Lancashire , United Kingdom.

ABSTRACT
Background. Although the trot is described as a diagonal gait, contacts of the diagonal pairs of hooves are not usually perfectly synchronized. Although subtle, the timing dissociation between contacts of each diagonal pair could have consequences on gait dynamics and provide insight into the functional strategies employed. This study explores the mechanical effects of different diagonal dissociation patterns when speed was matched between individuals and how these effects link to moderate, natural changes in trotting speed. We anticipate that hind-first diagonal dissociation at contact increases with speed, diagonal dissociation at contact can reduce collision-based energy losses and predominant dissociation patterns will be evident within individuals. Methods. The study was performed in two parts: in the first 17 horses performed speed-matched trotting trials and in the second, five horses each performed 10 trotting trials that represented a range of individually preferred speeds. Standard motion capture provided kinematic data that were synchronized with ground reaction force (GRF) data from a series of force plates. The data were analyzed further to determine temporal, speed, GRF, postural, mass distribution, moment, and collision dynamics parameters. Results. Fore-first, synchronous, and hind-first dissociations were found in horses trotting at (3.3 m/s ± 10%). In these speed-matched trials, mean centre of pressure (COP) cranio-caudal location differed significantly between the three dissociation categories. The COP moved systematically and significantly (P = .001) from being more caudally located in hind-first dissociation (mean location = 0.41 ± 0.04) through synchronous (0.36 ± 0.02) to a more cranial location in fore-first dissociation (0.32 ± 0.02). Dissociation patterns were found to influence function, posture, and balance parameters. Over a moderate speed range, peak vertical forelimb GRF had a strong relationship with dissociation time (R = .594; P < .01) and speed (R = .789; P < .01), but peak vertical hindlimb GRF did not have a significant relationship with dissociation time (R = .085; P > 0.05) or speed (R = .223; P = .023). Discussion. The results indicate that at moderate speeds individual horses use dissociation patterns that allow them to maintain trunk pitch stability through management of the cranio-caudal location of the COP. During the hoof-ground collisions, reduced mechanical energy losses were found in hind-first dissociations compared to fully synchronous contacts. As speed increased, only forelimb vertical peak force increased so dissociations tended towards hind-first, which shifted the net COP caudally and balanced trunk pitching moments.

No MeSH data available.


Related in: MedlinePlus

An example of the 25 segment model developed for each horse.(A) Sagittal plane view, (B) frontal plane view, (C) oblique view. The blue sphere represents the position of the centre of mass (COM). The cranio-caudal location of the COM is projected on to the ground and is shown as a yellow dot between fore and hindlimbs. The blue arrows represent the resultant ground reaction force vectors for fore and hind limbs. The green spheres represent the location of anatomical markers attached to the horse and the yellow lines represent the model segments. The origin and global coordinate system for the laboratory is depicted by the XYZ axes that can be seen underneath the horse model.
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fig-1: An example of the 25 segment model developed for each horse.(A) Sagittal plane view, (B) frontal plane view, (C) oblique view. The blue sphere represents the position of the centre of mass (COM). The cranio-caudal location of the COM is projected on to the ground and is shown as a yellow dot between fore and hindlimbs. The blue arrows represent the resultant ground reaction force vectors for fore and hind limbs. The green spheres represent the location of anatomical markers attached to the horse and the yellow lines represent the model segments. The origin and global coordinate system for the laboratory is depicted by the XYZ axes that can be seen underneath the horse model.

Mentions: Kinematic and force data were recorded and prepared for analysis and a 25 segment model (see Fig. 1) was developed for each horse as described by Hobbs, Richards & Clayton (2014) and, in accordance with the results of that study, the segmental model COM was adjusted to the COP ratio during standing by shifting the trunk COM location. Consequently, the cranio-caudal segmental model COM location matched the body COP location during standing. The standing COP ratio (COPSTAND) was determined as follows; (1)\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy}\usepackage{upgreek}\usepackage{mathrsfs}\setlength{\oddsidemargin}{-69pt}\begin{document}}{}\begin{eqnarray*}{\mathrm{COP}}_{\mathrm{STAND}}\mathrm{Ratio}= \frac{{\mathrm{GRFV }}_{F}}{{\mathrm{GRFV }}_{T}} \end{eqnarray*}\end{document}COPSTANDRatio=GRFVFGRFVTGRFVF = forelimb vertical force; GRFVT = summed forelimb and hindlimb vertical forces.


An exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in trotting horses.

Hobbs SJ, Bertram JE, Clayton HM - PeerJ (2016)

An example of the 25 segment model developed for each horse.(A) Sagittal plane view, (B) frontal plane view, (C) oblique view. The blue sphere represents the position of the centre of mass (COM). The cranio-caudal location of the COM is projected on to the ground and is shown as a yellow dot between fore and hindlimbs. The blue arrows represent the resultant ground reaction force vectors for fore and hind limbs. The green spheres represent the location of anatomical markers attached to the horse and the yellow lines represent the model segments. The origin and global coordinate system for the laboratory is depicted by the XYZ axes that can be seen underneath the horse model.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4933092&req=5

fig-1: An example of the 25 segment model developed for each horse.(A) Sagittal plane view, (B) frontal plane view, (C) oblique view. The blue sphere represents the position of the centre of mass (COM). The cranio-caudal location of the COM is projected on to the ground and is shown as a yellow dot between fore and hindlimbs. The blue arrows represent the resultant ground reaction force vectors for fore and hind limbs. The green spheres represent the location of anatomical markers attached to the horse and the yellow lines represent the model segments. The origin and global coordinate system for the laboratory is depicted by the XYZ axes that can be seen underneath the horse model.
Mentions: Kinematic and force data were recorded and prepared for analysis and a 25 segment model (see Fig. 1) was developed for each horse as described by Hobbs, Richards & Clayton (2014) and, in accordance with the results of that study, the segmental model COM was adjusted to the COP ratio during standing by shifting the trunk COM location. Consequently, the cranio-caudal segmental model COM location matched the body COP location during standing. The standing COP ratio (COPSTAND) was determined as follows; (1)\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy}\usepackage{upgreek}\usepackage{mathrsfs}\setlength{\oddsidemargin}{-69pt}\begin{document}}{}\begin{eqnarray*}{\mathrm{COP}}_{\mathrm{STAND}}\mathrm{Ratio}= \frac{{\mathrm{GRFV }}_{F}}{{\mathrm{GRFV }}_{T}} \end{eqnarray*}\end{document}COPSTANDRatio=GRFVFGRFVTGRFVF = forelimb vertical force; GRFVT = summed forelimb and hindlimb vertical forces.

Bottom Line: Discussion.The results indicate that at moderate speeds individual horses use dissociation patterns that allow them to maintain trunk pitch stability through management of the cranio-caudal location of the COP.During the hoof-ground collisions, reduced mechanical energy losses were found in hind-first dissociations compared to fully synchronous contacts.

View Article: PubMed Central - HTML - PubMed

Affiliation: Centre for Applied Sport and Exercise Sciences, University of Central Lancashire , Preston , Lancashire , United Kingdom.

ABSTRACT
Background. Although the trot is described as a diagonal gait, contacts of the diagonal pairs of hooves are not usually perfectly synchronized. Although subtle, the timing dissociation between contacts of each diagonal pair could have consequences on gait dynamics and provide insight into the functional strategies employed. This study explores the mechanical effects of different diagonal dissociation patterns when speed was matched between individuals and how these effects link to moderate, natural changes in trotting speed. We anticipate that hind-first diagonal dissociation at contact increases with speed, diagonal dissociation at contact can reduce collision-based energy losses and predominant dissociation patterns will be evident within individuals. Methods. The study was performed in two parts: in the first 17 horses performed speed-matched trotting trials and in the second, five horses each performed 10 trotting trials that represented a range of individually preferred speeds. Standard motion capture provided kinematic data that were synchronized with ground reaction force (GRF) data from a series of force plates. The data were analyzed further to determine temporal, speed, GRF, postural, mass distribution, moment, and collision dynamics parameters. Results. Fore-first, synchronous, and hind-first dissociations were found in horses trotting at (3.3 m/s ± 10%). In these speed-matched trials, mean centre of pressure (COP) cranio-caudal location differed significantly between the three dissociation categories. The COP moved systematically and significantly (P = .001) from being more caudally located in hind-first dissociation (mean location = 0.41 ± 0.04) through synchronous (0.36 ± 0.02) to a more cranial location in fore-first dissociation (0.32 ± 0.02). Dissociation patterns were found to influence function, posture, and balance parameters. Over a moderate speed range, peak vertical forelimb GRF had a strong relationship with dissociation time (R = .594; P < .01) and speed (R = .789; P < .01), but peak vertical hindlimb GRF did not have a significant relationship with dissociation time (R = .085; P > 0.05) or speed (R = .223; P = .023). Discussion. The results indicate that at moderate speeds individual horses use dissociation patterns that allow them to maintain trunk pitch stability through management of the cranio-caudal location of the COP. During the hoof-ground collisions, reduced mechanical energy losses were found in hind-first dissociations compared to fully synchronous contacts. As speed increased, only forelimb vertical peak force increased so dissociations tended towards hind-first, which shifted the net COP caudally and balanced trunk pitching moments.

No MeSH data available.


Related in: MedlinePlus