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Activating and Opening the (1)–(4)

Diagonal From Crossing to Functional Impulsion.

APPLIED BIOMECHANICS

This is not about crossing legs for its own sake. It is about organizing the diagonals so that propulsion, balance, and elevation can emerge progressively, without force or tension.

Activation and opening of the (1)–(4) diagonal(inside hind – outside fore)

Objective:

To achieve that the outside foreleg (4) does not only move forward, but begins to open along a diagonal trajectory, in synchrony with the crossing of the inside hind leg (1).

This coordination prepares the horse for active lateral work, developed progressively, without tension, blocking, or loss of balance.

Why is it important to work with the outside foreleg?

In the first stages of this work, when the horse is just beginning to cross the inside hind leg (1) under the belly, the outside foreleg (4) will usually continue to travel straight forward.

This is normal and entirely acceptable at this stage.

However, as the inside hind becomes more active, we often observe the following response: The outside hind leg (3) begins to step outward as a natural compensatory reaction to the increased crossing of the inside hind (1).

This reaction is understandable at this phase, but it is not yet functionally organized.

Here is where refinement begins.

Our goal is not crossing alone, but organized propulsion combined with balance and elevation.

Progressive phases of the exercise:

1.- Observe the reaction of the outside hind leg (3).Once the horse can calmly cross the inside hind leg (1) for three or four consecutive steps, the outside hind leg (3) will often begin to step outward. This outward step is a compensatory response, not yet a true pushing and supporting action.

At this stage, we do not correct it aggressively.

We observe it.

What we want, progressively, is for the outside hind leg to push and support, not merely react laterally.

2.- Change the position of the neck to change the body’s intention.

This is a key moment.

Teaching the crossing: Light flexion to the inside. Facilitates crossing of the inside hind leg (1).

Teaching impulsion: Neck straight. Activates the pushing function of the outside hind leg (3).With the neck straight, torsion in the topline is reduced. This encourages the horse to use the outside hind leg as a propulsive and stabilizing limb, instead of escaping outward.

The change is subtle, but essential.

3.- Opening the outside foreleg in diagonal (4). Once the following elements are present: Calm and consistent crossing of the inside hind leg (1),stability of the neck, clarity of the central body axis, we can begin to observe and influence the trajectory of the outside foreleg (4).

What we are looking for is that the outside foreleg does not continue straight forward, but begins to draw a diagonal line forward and outward.

This prepares: Yielding to the leg, from the ground or under saddle, the first steps toward shoulder-in, coordination of crossed diagonals, shortening and organization of the outside of the body, functional mobilization of the inside rib cage.

At this stage, relaxation of the jaw and the first elements of contact start to become relevant, as the outside rein begins to play a role... but this is another subject and not the purpose of this post.

Active biomechanics in this phase:

Inside hind leg (1).Crosses under the body ,Hip flexion and activation of abdominal muscles.

Outside hind leg (3).Pushes and supports Elevation of the trunk and controlled propulsion.

Outside foreleg (4).Opens in diagonal. Releases the external shoulder and allows lateral mobility without torsion Straight neck Stabilizes the axis Enables transmission of energy from the hindquarters

Pedagogical recommendations:

Do not rush to combine all elements at once.

Make sure the horse understands each component separately.

Rest between each micro achievement remains essential: pause, release, breathe.

Keep your emotional intention neutral and focused.

Do not demand mechanical precision too early.

Functional reference:

(1) Inside hind (left hind)Motor of crossing and engagement under the body.

(2) Inside fore (left fore)Guides the movement, receives less load in balance.

(3) Outside hind (right hind)Controls propulsion and stabilizes the curve.

(4) Outside fore (right fore)Opens the arc of the circle, key for lateral work.

Applied example:

When we ask the inside hind leg (1) to cross toward the centerline, we want its trajectory to orient toward the outside foreleg (4), which in turn should open diagonally forward and outward.

This is where true coordination of the diagonal begins.

This image illustrates a pedagogical moment within a learning process. It is not intended as a model of final posture, balance, or aesthetic ideal.

More to come soon

Isaac Ares

www.dressage-isaac.com