Hobbs, Sarah Jane and Clayton, Hilary M and Bertram, John EA An exploration of the influence of diagonal dissociation and moderate changes in speed on locomotor parameters in trotting horses. [DataSet]
Background. Although the trot is described as a diagonal gait, movements of the limb pairs 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 preferred 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, 5 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. Significant differences in speed-matched trials between all three dissociation categories were found for mean COP cranio-caudal location. The COP moved systematically and significantly (P=.001) from more caudally in hind-first dissociation (mean location = 0.41±0.04) through synchronous (0.36±0.02) to more cranially 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 (R=.594; P<.01) and speed (R=.789; P<.01), but peak vertical hindlimb GRF did not have a significant relationship with dissociation (R=.085; P>.05) or speed (R=.223; P=.023).
Discussion. The results indicate that at moderate speeds dissociation patterns allow trunk pitch stability to be maintained through management of the cranio-caudal location of the centre of pressure (COP). During the hoof-ground collisions, 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.
|Research / Data Type:||Collection - various types|
|Depositing User:||Sarah Jane Hobbs|
|Date Deposited:||11 Apr 2016 09:05|