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First published online December 14, 2007
Journal of Experimental Biology 211, 138-149 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.008243
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Steady locomotion in dogs: temporal and associated spatial coordination patterns and the effect of speed

Ludovic D. Maes*, Marc Herbin, Rémi Hackert, Vincent L. Bels and Anick Abourachid

CNRS, MNHN, Université P6, Col. De France, Muséum National d'Histoire Naturelle, Département Ecologie et Gestion de la Biodiversité, UMR 7179, Pavillon d'Anatomie Comparée, CP 55, 57 rue Cuvier, 75231 Paris cedex 05, France


Figure 1
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  		Fig. 1. Gait diagrams and track diagrams of one anteroposterior sequence (APS) at different speeds and gaits. Each colour corresponds to one foot: f1, 1-forelimb (red); f2, 2-forelimb (orange); h1, 1-hindlimb (dark green); h2, 2-hindlimb (pale green). On gait diagrams, coloured lines correspond to stances and coloured crosses represent the next footfall. On track diagrams, coloured squares indicate the positions of foot contacts on the runway. (A) APS temporal and spatial parameters [adapted from Abourachid et al. (Abourachid et al., 2007Go)]. Time lags, reflecting temporal coordination between forelimbs (fore lag; FL), hindlimbs (hind lag, HL) or pairs of limbs (pair lag; PL), are calculated as a percentage of f1 cycle duration. Space gaps, which express spatial coordination between the forelimbs (fore gap; FG), hindlimbs (hind gap; HG) or pairs of limbs (pair gap; PG), are expressed as a percentage of f1 stride length. (B) Two experimental gait (left) and track (right) diagrams for each gait. The two pairs of gait–track diagrams correspond to low (top) and high (bottom) speed for the considered gait. For each foot, the duration of the cycle decreases, whereas stride length increases with increasing speed. The changes in kinematics and limb coordination support this decrease in cycle duration and increase in stride length.

 

Figure 2
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  		Fig. 2. Distribution of the sequences over the whole range of speeds (A). The number of sequences is represented for each gait: lateral walk (blue), pace (red), trot (green), transverse gallop (violet), slow (yellow) and fast (brown) rotary gallop. Frequency of appearance of the first suspension phase, sp1 (B) or the second suspension phase, sp2 (C), plotted against ranges of speed or Froude number for each gait. Frequencies are plotted as bars. Stars indicate the presence of the considered gait without a corresponding suspension phase. N, number of sequences; Nsp1, number of sequences with sp1; Nsp2, number of sequences with sp2. Sp1 and Sp2 are explained in the text.

 

Figure 3
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  		Fig. 3. Stance (filled diamonds), swing (open triangles) and cycle (filled squares) durations plotted against speed (u) or Froude number (Fr) for each gait: lateral walk (blue), pace (red), trot (green), transverse gallop (violet), slow (yellow) and fast (brown) rotary gallop.

 

Figure 4
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  		Fig. 4. Duty factor (A) and fore–hind duty factor difference (B) plotted against speed or Froude number for each gait: lateral walk (blue), pace (red), trot (green), transverse gallop (violet), slow (yellow) and fast (brown) rotary gallop.

 

Figure 5
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  		Fig. 5. Relationship between stride length and speed or Froude number for each gait: lateral walk (blue), pace (red), trot (green), transverse gallop (violet), slow (yellow) and fast (brown) rotary gallop.

 

Figure 6
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  		Fig. 6. Fore lag (A; FL), hind lag (B; HL), fore gap (C; FG) and hind gap (D; HG), plotted against speed or Froude number for each gait: lateral walk (blue), pace (red), trot (green), transverse gallop (violet), slow (yellow) and fast (brown) rotary gallop.

 

Figure 7
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  		Fig. 7. Pair lag (A; PL), pair gap (B; PG) and pair gap added to trunk length (C; PG+TR) plotted against speed or Froude number for each gait: lateral walk (blue), pace (red), trot (green), transverse gallop (violet), slow (yellow) and fast (brown) rotary gallop.

 

Figure 8
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  		Fig. 8. Particular cases in the relationship between temporal and spatial interpair coordination. In the static posture, the delay in pair gap (PG) is easy to explain as a function of pair lag (PL). TR, trunk length; u, speed.

 




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