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Is Foot Placement Related to Body Movement Asymmetry During Circular Locomotion?
Author(s) -
Starke S,
Merritt J,
Stubbs N,
Pfau T,
Clayton H
Publication year - 2014
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.12267_148
Subject(s) - asymmetry , centripetal force , movement (music) , kinematics , mathematics , anatomy , foot (prosody) , sacrum , geodesy , orthodontics , geometry , physical medicine and rehabilitation , physics , geology , medicine , classical mechanics , quantum mechanics , mechanics , acoustics , linguistics , philosophy
The mechanics of circular locomotion are relevant to equine training and lameness evaluation. Circular trotting is associated with asymmetries in upper body movement. This study investigated whether changes in foot placement explain upper body asymmetry and whether this asymmetry is dependent on centripetal force. Methods Six functionally sound horses walked and trotted on a 6 m diameter circle and straight line at their preferred speed. Optical motion capture ( M otion A nalysis C orp.) recorded foot position in 3D space. For each limb, horizontal foot placement was calculated in a body‐based reference system. Vertical displacement asymmetry ( V ector S um, VS ) was calculated from inertial sensors ( X sens, The N etherlands) attached above poll, withers, sacrum and tubera coxae. Variables were compared across movement directions and gaits using repeated measures ANOVA (parametric datasets) or F riedman T est (non‐parametric datasets). Results Changes in foot placement relative to body position and orientation were small for both gaits in cranio‐caudal and medio‐lateral direction (maximum effect size at walk/trot: 66/102 mm). The amount of systematic movement asymmetry on the circle was comparable between walk (mean VS head/sacrum: 36/15 mm) and trot (30/15 mm, respectively), despite a 3‐fold higher centripetal force during trot. Conclusions Foot placement relative to body position and line of travel does not differ markedly between straight line and circle and cannot solely account for the observed upper body movement asymmetry. Since movement asymmetry was comparable at walk and trot (despite differences in adopted movement pattern), centripetal force may not be the primary variable responsible for movement asymmetry on the circle. Ethical Animal Research The study was approved by the MSU Institutional A nimal C are and U se C ommittee, protocol #06/11‐112‐00. Sources of funding: Sandra Starke's collaborative research visit for this project was funded by the B ritish Society for A nimal Science ( BSAS ), M urray Black Award. Competing interests: none.