Human Asymmetry - Patterns, Patterns Everywhere

David Kempsell is the co-founder and Managing Director of First Thought Equine Ltd, the company behind WOW Saddles, Flair, FreeSpace, Korrector, and Duskin Saddles.

He is also a qualified saddle fitter with The Society of Master Saddlers (SMS), bringing scientific precision, logical design expertise, and problem-solving skills to saddlery - all grounded in a lifelong passion for riding and upholding the highest standards of Ethical Equine Performance.

In the first instalment of this blog series we looked at the broad factors that influence asymmetry within the musculoskeletal system. Here, we will dig deeper into human asymmetry and how it affects the way a rider loads a horse; and, in turn, how the horse develops its own asymmetries.

When riding in a saddle, the rider must sit centrally if their weight is to be distributed evenly across the horse’s back. It almost goes without saying that the saddle itself must fit the horse correctly. But even with a well-fitting saddle, the rider’s own structure plays a major role in how that load is applied.

What Does the Rider Actually Sit On?

When you sit, you are cushioned by muscle and soft tissue around the pelvis, but the primary contact points are the seat bones; the tubera ischiadica.

The difficulty is that the position of the pelvis, and therefore the position of those seat bones, depends heavily on the legs and the surrounding musculature. These structures determine whether the pelvis sits in what we might call a neutral position; the same neutral alignment you would have when standing comfortably upright.

As already discussed, leg length in humans can vary. Differences of up to around 15 mm can exist without producing an obvious limp. The body compensates for this discrepancy, and most of that compensation happens through the orientation of each os coxae; the two halves of the pelvis.

Each os coxae is formed by the fusion of three bones:

• the ilium

• the ischium

• the pubis

  
  

The right and left os coxae meet at the front at the pubic symphysis and join the sacrum at the back, forming the pelvic girdle. The hip joints connect the legs to this structure, while the sacrum forms the base of the spinal column.

As we grow, the skeleton adapts to differences in loading and limb length. By the early teenage years, the bones have largely fused in a way that accommodates whatever asymmetry exists. These adaptations allow us to function normally, even if we are not perfectly symmetrical.

Dominance and Pelvic Orientation

Consider a rider with a slightly longer right leg.

To keep the spine upright and the head balanced, the body will often rotate and tip the pelvis. The right side of the pelvis may be carried slightly up and forward while the sacrum attempts to remain level so the spine can stay relatively straight.

This longer leg is often also the dominant or “dynamic” leg; the one more involved in active movement. Just as a tennis player develops more muscle and bone density in their racket arm, the dominant leg can develop greater mass and, over time, even a subtle increase in length.

The pelvis compensates and rotates throwing the hip joint forward and that seat bone comes up. 

These adaptations are natural and helpful. They allow us to function efficiently despite asymmetry. However, they are not perfect solutions. The spine still makes compensations, and the overarching aim of the body is simply to keep the head balanced over the centre of gravity.

The Seat of the Matter

These pelvic adaptations become problematic when trying to sit on a horse and achieve symmetrical loading.

Imagine a rider with a neutral spine attempting to sit on a flat surface. If one seat bone sits slightly lower than the other, it will make contact first. The higher seat bone cannot meet the surface without the pelvis tilting away from neutral. As the pelvis tips, what may only be a few millimetres of difference at the seat bones can translate into centimetres of deviation higher up the spine.

The body instinctively corrects for this. Our sense of balance and self-preservation demands that the head remains centred. To achieve this, the spine subtly curves; often forming a mild functional scoliosis. The shoulders then appear twisted, with one sitting further back than the other.

This is why riders frequently look crooked in the saddle even when they feel straight.

And this is where patterns begin to emerge.

The rider believes they are centred.The horse feels the asymmetry.Over time, the horse adapts to the load it receives.

Understanding these patterns is the first step in managing them.

A truly harmonious partnership begins with perfect balance and symmetry

WOW make the world’s only saddles with seatbone support and Flair™ air flocking, providing the ultimate saddle balance by correcting asymmetry in both horse and rider.