Matching spacing of diagonal pairs and prolonging tempo can be addressed by riding selected transitions. This diagram summarizes some relations of a good medium walk to other gaits in terms of the diagonal spacing of stance legs. In this way, walk work can serve as a foundation for developing collection and the timing of cadence. Relations shown between gaits are based on a rider’s feel of diagonal pair timing in each gait. Transitions involve the gymnastic effort to cross a VELOCITY GAP as well as a swing phase leg position gap (PHASE GAP).

1) A rider can know by feel which half of a gait the horse is performing because the gait-specific motions of the back plus the muscles that work the legs in the air can be felt as the horse cycles through its gaits,
2) A rider may select either lead of the canter or either half (Right Hind or Left Hind touch down) of walk or trot for a transition,
3) A rider may produce collection of the first degree or level balance by riding dressage transitions between medium walk and either trot or canter. This produces a basic version of collected trot and collected canter from medium walk because the timing of leg swaps that produce fluency and promptness develop core muscle strength.
4) Collection in level balance develops enough core muscle strength to manage modest extension (control of momentum),
5) Progression from collected walk to piaffe and passage redevelops the original walk-trot transition in a more “advanced” context. The transition is enabled by the strength to maintain a cadenced walk where the diagonal pair reaches mid stance nearly simultaneously. This tempo permits

a) hindquarters and forehand to match braking/propulsion of forelegs and hindlegs at mid stance, and
b) the diagonal swing legs to find their positions for piaffe without hesitation or hurry.

6) Transitions up and down for dressage take about half a second, in contrast to a longer series if the transition is rushed or on the forehand. If this seems strange, the images below could help clarify the issues of timing. A rushed transition does not have enough time for swing legs to find new positions for the next gait, so they often land short and ground covering character of the new gait is decreased. A transition on the forehand interferes with both balance and timing of the new gait, because the hind leg should be positioned so it can be effective at propulsion in the next stride of the new gait.

Dressage transitions involve a number of stance limb positions that brake, support, propel a horse across "velocity gaps" between dressage gaits as well as make the phase adjustment of legs when they are in swing phase. If this sounds like a neuromuscular achievement, it is!

Once a horse has mastered prolonged balance requirements on each diagonal pair at nearly simultaneous mid stance, the base of support can be adjusted gradually to achieve collection of the second degree (the spacing of collected walk plus cadence appears in passage and piaffe. The canter for pirouettes has stance positions that are specialized for that movement. In increasingly collected forms of canter, the diagonal pair and duration of the stride moment when three legs are grounded gradually absorb the time spent in suspension. Rather than a fault, this progression of balance on two and three legs creates predictable tempo and capacity to balance with minimal advance per step on a small circle for a pirouette, or these leg placements support fluent halts from canter. It is, however, very "heavy lifting" as mass of horse plus rider is moved in a deliberate, controlled fashion.

The value of collection is indicated by an increased number of options for riding gymnastic transitions. Canter for pirouettes has the diagonal stance pair spacing for collected walk with swing phase legs in similar position to those of one phase of collected walk. This is one indication of how crucial accurate timing of transition aids becomes for development of high collection with clear elevation of poll and withers relative to the croup (relative elevation).

Correct timing of aids with the stance phase hind leg encourages a horse to make a transition from walk into the chosen gait without shifting diagonal pair stance distance by making the transition via a series of limb positions (not shown here). Spreading the stance distance too much is an evasion of collected trot or canter from medium walk (about1.5 to 2 m/s). It is an understandable tactic for the horse because a wider distance at stance adjusts the braking/propulsion relationship to work in moving the body. Quicker steps are less demanding of effort from the large muscles that maintain spine posture and that operate the legs.

In a transition from collected walk to piaffe advancing, a soft passage or the school walk (pas d'ecole, see note a), the longer distance is an intermediate stage in developing cadence (prolongation of stance time: see note b) and in coordination of braking and propulsion phases of fore legs and hind legs. Right or left hind makes a conveient reference because the lump made by contracting medial gluteal muscles can be felt under the saddle.

NOTES:
a) The school walk or pas d'ecole is a gait not widely practiced in our times. It possibly fell into disuse because some trainers began to regard it as a flawed gait, which would have been the case if it was performed without impulsion. Old masters used the pas d'ecole to develop passage, piaffe and the transitions between them. It is a cadenced stepping trot without suspension or time off the ground. The school walk requires enormous concentration and balance on the part of a horse and tact (invincible softness) on the part of a rider. If carefully done, it allows a horse to learn which muscles to activate or deactivate during the change from forward movement (passage) to piaffe (in place) and vice versa. It is a strenuous weight carrying exercise almost without impact and should be used with discretion. I have a video of Egon von Neindorff performing a vigorous school walk on his horse Jaguar. Will try to compress it and have it available for viewing.

b) There are occasional misconceptions about the source of cadenced gaits as time spent with all four legs off the ground. Prolongation of suspension requires that a horse "come more off the ground" with its steps. Physics dictates that the fall back to earth takes 32 feet per second per second, making the landing of half a ton or more of mass from even a few inches of height a strain on tendons, ligaments, muscles and bone. Rather than achieve cadence by suspension, it can be approached by gradually prolonging the time a horse spends in stance balanced on a diagonal pair. This develops elastic quality to gaits with minimal stress on limbs. It also allows time for a horse in passage to make the "grand gesture" with swing phase legs, giving artistic expression to this high school air. The character of cadence can be examined on video by advancing the tape one frame at a time and counting the frames in a stride where the horse is on or completely off the ground (standard video is 29.95 frames per second).

COMPARISON: Posture of Horse with Right Diagonal Pair Grounded (RH-LF)
(Vertical 3 horse image panels are half size: click on each one to display at full size.)

All images are checked against still photographs and video frames. All are outputs from a computer model developed by the author and are not drawings. Standards for canter pirouette posture are horses of several breeds ridden by Egon von Neindorff, Waldemar Seunig or Ernst Lindenbauer.

For reference, here is an image of muscles shown in the diagrams above. Click on the image to show at full size.