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First published online May 21, 2007
Journal of Experimental Biology 210, 1885-1896 (2007)
Published by The Company of Biologists 2007
doi: 10.1242/jeb.02774
Validation of vertical ground reaction forces on individual limbs calculated from kinematics of horse locomotion
1 Institute for Fundamental and Clinical Human Movement Sciences, Vrije
Universiteit, van der Boechorstraat 9, NL-1081 BT Amsterdam, The
Netherlands
2 Department of Equine Sciences, Faculty of Veterinary Medicine Utrecht
University, Yalelaan 12, NL-3584 CM Utrecht, The Netherlands
3 Department of Equine Studies, Swedish University of Agricultural Sciences,
750 05 Uppsala, Sweden
4 Equine Hospital, Vetsuisse Faculty, University of Zurich,
Winterthurerstrasse 260, CH-8057 Zurich, Switzerland
* Author for correspondence (e-mail: M_F_Bobbert{at}fbw.vu.nl)
Accepted 7 March 2007
The purpose of this study was to determine whether individual limb forces could be calculated accurately from kinematics of trotting and walking horses. We collected kinematic data and measured vertical ground reaction forces on the individual limbs of seven Warmblood dressage horses, trotting at 3.4 m s1 and walking at 1.6 m s1 on a treadmill. First, using a segmental model, we calculated from kinematics the total ground reaction force vector and its moment arm relative to each of the hoofs. Second, for phases in which the body was supported by only two limbs, we calculated the individual reaction forces on these limbs. Third, we assumed that the distal limbs operated as linear springs, and determined their forcelength relationships using calculated individual limb forces at trot. Finally, we calculated individual limb forcetime histories from distal limb lengths. A good correspondence was obtained between calculated and measured individual limb forces. At trot, the average peak vertical reaction force on the forelimb was calculated to be 11.5±0.9 N kg1 and measured to be 11.7±0.9 N kg1, and for the hindlimb these values were 9.8±0.7 N kg1 and 10.0±0.6 N kg1, respectively. At walk, the average peak vertical reaction force on the forelimb was calculated to be 6.9±0.5 N kg1 and measured to be 7.1±0.3 N kg1, and for the hindlimb these values were 4.8±0.5 N kg1 and 4.7±0.3 N kg1, respectively. It was concluded that the proposed method of calculating individual limb reaction forces is sufficiently accurate to detect changes in loading reported in the literature for mild to moderate lameness at trot.
Key words: Equus caballus, trot, walk, biomechanics, limb stiffness, model, duty factor