Figure 1.
Accelerometer data analysis along the vertical axis at the trot and canter.
Panel A: Representative coordination patterns between horse's limbs for each gait. Panel B: Recorded dorsoventral (DV) acceleration signal. Panel C: Calculated DV displacement. As shown by the vertical dashed lines, the DV displacement presents two repeated oscillations per stride at the trot (2 contact and flight phases) and only one at the canter. The corresponding DV frequency at the trot is thus higher than at the canter. The description of the acceleration data is based on the previous works of Barrey et al. [1], [10] at the trot and canter, respectively.
Figure 2.
Lissajous plots of horse (x axis) and rider's (y axis) vertical displacements.
A angle reflects the ratio between the amplitude of the horse's dorsoventral (DV) and rider's craniocaudal (CC) displacements. A reduction of the rider's CC displacement, while horse's DV displacement was kept constant, resulted in a smaller α angle (panel B vs. A). The global form of the Lissajous plot illustrates difference in spatiotemporal relationship (relative phase) between the horse and the rider along the stride cycle. The sign of the relative phase is related to the sense of rotation of the plot indicated by the small arrows (counter-clockwise for a positive delay when the rider's reversal movement is delayed as compared to the horse's one).
Figure 3.
Quantification of the stride occurrences for each of the two riding techniques per horse's gait.
The stride distribution at the trot (left graph) and at the canter (right graph) is based on the rider's craniocaudal (CC) displacement, which is of lower amplitude in the two-point technique (A and C) as compared to its value in either sitting canter (D) or rising trot (B). The latter technique was mostly used by the present horse-rider system (dyad 1) in the two loops under interest.
Figure 4.
Influence of the gait pattern and riding technique on the horse-rider coupling (HRC).
Each Lissajous plot combines the horse's dorsoventral (DV) displacement (horizontal axis) with the rider's craniocaudal (CC) one (vertical axis) for each horse's gait (panel A vs. B) and riding technique (left vs. right panels). The shape of the Lissajous plot is clearly gait specific: the trot (panel B) is characterized by two successive coordination patterns instead of one at the canter (panel A), which may either overlap (two-point technique) or differ from each other (rising trot). At both trot and canter differentiation of the riding technique can be made based on the lower inclination (α angle) of the Lissajous plot in between its two points of reversal. Emphasizing the stability of the HRC patterns, the mean Lissajous plot (black line) is very similar to the plots of 100 successive strides (grey line).
Figure 5.
Influence of horse's gaits and riding techniques on relative phase at the lowest reversal point.
Mean and standard deviations of the relative phase at the lowest point of the horse's and the rider's vertical displacements in each riding gait and technique. A positive RP value means that the horse reaches the lowest point before the rider. The higher RP values in the two-point techniques indicate a greater delay than in the two other techniques (rising trot and sitting canter).
Figure 6.
Differentiation of horse's gaits and riding techniques based on the α angle.
(A) Mean (± SD) value of α angle for each of the two riding techniques per gait and (B) associated gait proportion for the two loops under interest for dyad 1. At both trot and canter gaits, the two-point technique is systematically associated with a smaller α angle. More than half of the strides are performed at the rising trot.
Figure 7.
Lissajous plots characterizing each riding technique for the six dyads.
Individual Lissajous plots (averaged over 100 strides) for each combination of horse's gait (panels A & B) and riding technique (left and right panels).
Table 1.
Proportion of each combination of horse gait-riding technique per dyad.
Table 2.
Group mean and SD values of the different variables in the four horse gait-riding technique combinations.