In the above movie, Vulkan (Württemberger gelding) is performing left collected canter while being free longed. Let the movie play through and then use the controller to step through the frames to see how the suspension of medium canter is absorbed into the time the diagonal pair is grounded in collected canter. Collection in dressage gaits increases contact time with the ground.
Issues of engagement are illustrated by comparing ordinary, collected and medium canters. Engagement judged in dressage performance is defined as "increased flexion of the joints of the hind legs supporting a greater proportion of the load; a prerequisite for thrust/impulsion." The relation between collection and engagement is that collection is a special case of engagement. Engagement is a condition of the spine posture in any dressage gait that involves trained propulsive function of the hindquarters and generally positive relative elevation of withers and croup (developed gymnastic capacity).
Differences between collected canter and medium canter are shown in the table of still frames below. The horses are Vulkan and Rio Sereno (Rhinelander cross). Medium canter has the most even spacing of phases: three hoof beats followed by suspension. General data for gaits are given below. These are dressage gaits and do not cover the full range of athletic performance of horses. For instance, gallop might be 17 meters/second.
Additional data on gaits come from the following articles and are available in a number of books.
•Denoix, 1999 (Spinal biomechanics and functional anatomy, Veterinary Clinics of N. Am.: Equine Practice, Vol. 15 No. 1, pp. 27-60)
•Clayton (1994 Comparison of Collected, Medium and Extended Canters Equine Vet. J. Suppl. 17, pp. 16-19: 1994
Comparison of the Stride Kinematics of Collected, Medium and Extended Trot
Equine Vet. J. 26, pp. 230-234:1995 Comparison of the Stride Kinematics of Collected, Medium and Extended Walks in Horses
Am. J. Vet. Res. 56, pp. 849-852: 1995
Classification of Collected Trot, Piaffe and Passage Using Stance Phase Temporal Variables, Equine Vet. J. Suppl. 23, pp. 54-57).
| GAIT |
Approximate Velocity
(meters/second)
|
Tempo or Stride Rate
(strides per minute)
|
| WALK |
1.5 to 2+
|
51 to 57
|
| TROT |
4 to 5
|
75 to 84
|
| CANTER |
collected 3, medium 4, extended 7
|
102 to 89
|
| Canter pirouettes |
n/a
|
63 to 65
|
| Piaffe |
zero to 0.4
|
52 - 55
|
| Passage |
1.5 to 1.8
|
53 to 56
|
In collected canter, the diagonal pair lands sooner (in terms of percent of stride) than in the medium canter. Collected tempo is slower and the horse will spend a larger percentage of the stride on three or two legs. The outside hind lands before the inside fore leaves the ground (frame 6), creating a brief diagonal pair in place of suspension. Collected canter has longer contact time than medium canter and covers less ground per stride, as indicated by the angle of separation of the hind legs (frames 2, comparison is approximate, as angles of view are slightly different). In the collected canter, the foreleg of the diagonal pair reaches mid stance sooner than the same phase of the medium canter (frames 2), another indication of the amount of ground covered in the two canters.
Comparison of collected and medium canters (free longe):
selected frames from digital video of one stride.
| Collected Canter Vulkan |
2
|
3
|
4
|
5
|
6
(no suspension)
|
 |
 |
 |
 |
 |
 |
Medium Canter
Rio Sereno |
2
|
3
|
4
|
5
|
6
(suspension)
|
 |
 |
 |
 |
 |
 |
In both canters (A collected, C medium), the horses are engaged more than they would be in ordinary canter, as indicated by the flexion of the joint between the lumbar spine and the sacrum (S-L joint). This places the trailing hind leg (time one) well under the horse. This landing from suspension sets the conditions for the next part of the stride, which is why it is important to look at the posture of the horse at this moment. Classical equitation authors and current judges speak of "equal bending of the joints of the hindquarters" as a characteristic of engagement. A sense of the anatomy involved is indicated in the diagram B below (medium canter time one). Diagram D shows a front view of the sacrum part of the SL joint, emphasizing the extended articular surfaces unique to equids. It is an anatomical feature that supports powerful flexion for engagement. Diagram E shows some of the complexity of movement at this critical joint.
Engagement of the horses in A and C is reflected in the relative elevation of their withers above the croup at landing of the trailing hind leg. Note that the lift in the withers in A is correlated with intense activity of the complexus system of muscles to maintain the alignment of neck vertebrae. This activity appears as a continuous "roll" of muscle from the back of the jaw to the shoulder. Click on images to enlarge.
In the diagram B above, labels indicate leading and trailing legs for canter as well as the composition of the "elastic ring" of the horse. The elastic ring is made up of a variety of biological materials with different mechanical properties that respond to or integrate actions of the legs. These are bone (stiffest component), ligaments (elastic response), cartilage (intermediate between bone, ligament, or "stiff elastic"), and muscle (active, contractile, elastic and can act as brace, strut or motor). Muscular activity in the trunk and neck allows the horse to "tune' the responses of the elastic ring to a specific gait.
