Diagonals refer to the pairing of the horse’s legs during trot and the convention of rising — or posting — in time with a specific diagonal pair. At trot, the horse moves in two diagonal pairs: the left foreleg and right hind move together, then the right foreleg and left hind. A rider posting to the trot rises as one pair lifts and sits as the other lifts. Which diagonal you choose affects balance, straightness, and muscular development in the horse.
How to Identify Your Diagonal
The simplest method is to watch the horse’s outside shoulder as you post. When you rise, the outside shoulder should be moving forward. This is the correct diagonal for flatwork — you sit as the outside hind engages, encouraging impulsion and collection on a circle.
If you prefer to feel rather than look, sit quietly for a moment and notice which hip lifts you — it will correspond to the same side as your rising diagonal. With practice, identifying and correcting your diagonal becomes instinctive and requires no visual check.
Why the Correct Diagonal Matters
Consistently rising on the same diagonal causes the horse to develop unevenly. The muscles under the rider at the sitting phase work harder; those under the rising phase receive relative relief. Over time, a horse always ridden on the same diagonal in the same direction will show asymmetric muscular development — often visible as unevenness behind the saddle or inconsistent engagement from each hind leg.
Correct diagonal use also supports balance on circles. On a 20-metre circle to the left, the correct diagonal is the left diagonal — you rise as the left fore and right hind lift. This frees the inside hind to step under and engage during the sitting phase, supporting correct bend and rhythm. Riding on the wrong diagonal on a circle makes it harder for the horse to balance, pushes the horse to fall in or drift out, and disrupts the quality of the rhythm.
How to Change the Diagonal
To change diagonal, sit for one extra beat before rising again. This is done automatically when changing the rein — as you cross the centre line or diagonal of the arena, sit for one beat and pick up the new diagonal. Failing to change diagonal when changing direction is a common error in early schooling and is penalised in dressage tests.
Some horses develop a strong preference for one diagonal and feel distinctly uneven on the other. Mild asymmetry is normal and usually resolves with correct, varied training. Significant asymmetry — where the horse feels choppy, short-stepping, or uncomfortable on one diagonal — warrants a veterinary assessment to rule out hind limb pain or back issues.
Diagonals Compared to Canter Leads
The concept of diagonals applies only to rising trot. At canter, the relevant concept is the canter lead — which foreleg leads the sequence. The two are related in that on a circle the correct canter lead and the correct trot diagonal are both determined by the direction of travel, but they are distinct concepts requiring separate awareness. For rider position and how it influences these choices, see Equitation and Inside Leg.
Frequently Asked Questions
What happens if I ride on the wrong diagonal?
On a circle, the wrong diagonal makes it harder for the horse to balance, can cause the horse to fall in or drift, and over time contributes to uneven muscular development. In a dressage test, being on the wrong diagonal is visible to the judge and attracts marks deductions. Correct yourself by sitting for one extra beat. In hacking and general schooling, the impact is less acute but riders should still change diagonal regularly to ensure even loading of the horse’s hindquarters.
Does diagonal matter on straight lines?
Yes, but less critically than on circles. On straight lines and long sides of the arena, alternating diagonals regularly is good practice. It ensures even muscle loading across both hind limbs and prevents the horse from becoming habitually stiffer on one rein. Changing diagonal every few minutes during a long hack or schooling session is a simple, effective way to support even development.
My horse feels very different on each diagonal — is that normal?
A mild difference is normal and reflects the natural one-sidedness present in all horses, just as most humans favour one hand. A significant difference — particularly if the horse feels choppy, uneven, or resistant on one diagonal — warrants investigation. A veterinary examination to rule out hind limb asymmetry or back pain is a sensible first step, especially in horses in regular work or those that have recently changed in way of going.