Premium
The Effect of Centre of Mass Location on Pitching Moments in Trotting Horses
Author(s) -
Hobbs S,
Richards J,
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_125
Subject(s) - warmblood , stride , mathematics , kinematics , moment (physics) , forelimb , anatomy , physical medicine and rehabilitation , horse , physics , medicine , geology , paleontology , classical mechanics
The diagonal limb support pattern at trot provides pitch and roll stability, controlled by regulating pitching moments about the centre of mass ( COM ). Correct COM location is critical in calculation of pitching moments, as COM location influences the contribution of loading in the fore and hindlimbs. This study examined the effect of COM location on pitching moments in trotting horses and explored how COM location could influence balance. Methods Kinematic (120 H z) and GRF (4 force plates, 960 H z) data were collected at trot from three strides of eight horses overground. The position of the COM was determined from the weighted summation of the segmental COMs from previously determined inertial data of Warmblood horses. The COM of the standing model was manipulated cranially and caudally to test the effects of pitching moments during trotting. Pitching moments were calculated for each manipulation of the model and their relationship determined using reduced major axis regression. Results Over the stride, the moments must sum to zero to prevent accumulation of rotational motion. This was found when the weight on the forelimbs in standing was 58.7% ± 3% (mean ± 95% C . I .). With this weight distribution moments were typically nose‐up changing to nose‐down at around 35% of stance, and then reversing again to nose‐up in late stance. Conclusions Divergence of the COM from the COP creating a vertical force moment arm prior to midstance may aid in accelerating the COM about the hind foot, thereby passively assisting hindlimb propulsion. Lower forelimb weighting resulted in mean nose‐up moments. Higher forelimb weighting resulted in mean nose‐down moments. Both would cause an accumulation of pitching motion. Ethical Animal Research The study was performed with approval from the institutional animal care and use committee under protocol number 02/08‐020‐00. Sources of funding: This study was funded by M ichigan S tate U niversity and the U niversity of C entral L ancashire. Competing interests: none.