Flying Changes of Leg in Canter (continued)
The flying change from right canter (counter canter) to left canter occurs in a stride where the hind legs swap position and the bend is changed. Still Frames 2 and 9 show the right and left canters respectively at Time 3 (horse rocks forward on inside fore). The difference in phasing of the hind legs from the change reflects the preparation for landing Time 1 of the true canter (outside hind). Still frames from the change stride are 6-8. Frames 1 and 10 show the outside hind of the right and left leads grounded.
The change stride has its own pattern of limb phases and is not a standard canter stride (see Frames 6-8). This phase/interlimb coordination difference is why viewing a photo tells an observer the horse is performing a change rather than a canter stride.
In performing changes, the horse faces the challenge of swapping the hind legs or finishing some of the toe-off thrust of a regular canter stride.
This limb swap/thrust at toe-off during the change is why many horses lose impulsion in sequence changes. As the series of changes gets closer and closer together (fewer intervening canter strides), the recovery of thrust lost in the swap of the change must be accomplished with fewer intervening canter strides. This is why balance/straightness in the canter in which the changes are embedded is so important in maintaining their fluency and regularity.
And the flying change from left canter to right canter...