Acceleration and balance in trotting dogs.
During quadrupedal trotting, diagonal pairs of limbs are set down in unison and exert forces on the ground simultaneously. Ground-reaction forces on individual limbs of trotting dogs were measured separately using a series of four force platforms. Vertical and fore-aft impulses were determined for each limb from the force/time recordings. When mean fore-aft acceleration of the body was zero in a given trotting step (steady state), the fraction of vertical impulse on the forelimb was equal to the fraction of body weight supported by the forelimbs during standing (approximately 60 %). When dogs accelerated or decelerated during a trotting step, the vertical impulse was redistributed to the hindlimb or forelimb, respectively. This redistribution of the vertical impulse is due to a moment exerted about the pitch axis of the body by fore-aft accelerating and decelerating forces. Vertical forces exerted by the forelimb and hindlimb resist this pitching moment, providing stability during fore-aft acceleration and deceleration.
Lee
D V
DV
College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA. lee@biology.utah.edu
Bertram
J E
JE
Todhunter
R J
RJ
D000818:Animals; D001699:Biometry; D004285:Dogs / Q000033:anatomy & histology / Q000502:physiology*; D005260:Female; D005552:Forelimb / Q000502:physiology; D005684:Gait / Q000502:physiology*; D006614:Hindlimb / Q000502:physiology; D007700:Kinetics; D008297:Male; D004856:Postural Balance / Q000502:physiology*; D011312:Pressure; D012420:Running / Q000502:physiology*; D014741:Video Recording