It is a reality that everybody is dominant on one side of their body or the other. As human beings it’s normal that we’re asymmetrical. Think for a moment about the core axial organ configuration of the human body – we have a heart on the left and a liver on the right. Our side dominance, although often exaggerated by the jobs we do or the sports we play, is a result of our internal asymmetrical design and not handedness. The human body is neurologically driven to balance itself between the left and right halves of the body.
But what happens when the asymmetrical activities of the body are not balanced or there is over use, under use or misuse of the respective joints and muscles such that structural imbalances and musculo-skeletal pain syndromes eventuate?
These concepts of structural weaknesses and instabilities can explain how a person develops a gradual onset of pain only on one side or why a joint on one side wears out faster than the other.
Achieving a state of “neutral” or balanced asymmetrical function is beneficial for those in rehabilitation or injury prevention. Moreover, it’s highly valuable for those who wish to enhance athletic performance and movement variability. Neutrality will be considered in this post as a transitional zone an individual moves into between both ends of a given range of motion.
Neutrality is the transitional zone an individual moves through between both ends of a given range of motion
Let’s take a look at the lumbo-pelvic-femoral complex to take these ideas further.
The lumbo-pelvic-femoral complex is a term used to collectively describe the lumbar spine, pelvis and hip joints and how they function as an integrated system.
This system is made up of 6 joints, which are arranged to create a «ring of bones»:
A pubic symphysis at the front, 2 sacroiliac joints at the back, 2 hip joints (ball-and-socket joints) at the sides and an interface between L5-S1 (last bone of the lumbar spine to the top bone of the sacrum S1).
Due to the nature of this ring, you cannot get movement on one side of the ring of bones without having an opposite or reverse influence on the other side of the ring of bones. Each part has a direct influence on the all the other parts.
Consider for a moment the rotation of the pelvic bones in an upright position:
A forward and downward movement of the pelvis on the heads of the thigh bones is called anterior rotation or flexion.
A backward and upwards movement of the pelvis on the heads of the thigh bones is called posterior rotation or extension.
What happens to the other parts in this ring of bones when the pelvis rotates in one direction or the other?
When the pelvis tilts forwards (anteriorly), the lumbar spine extends (arches) and the hips flex.
When the pelvis tilts backwards (posteriorly), the lumbar spine flexes (flattens) and the hips extend.
However, these movements have only described movement of the bones in one plane of motion – the sagittal plane. When looking at the lumbo-pelvic-femoral complex, it is appropriate to consider the tri-planar relationships between the bones. Tri-planar movement is any movement that occurs through all three planes of motion (sagittal, frontal, transverse). Because bones and muscles change their position in locomotion / bipedal gait.
Let’s consider a snippet of the gait cycle for example. When one side of the pelvis advances and moves forward ahead of the opposite side, there is an oblique axis across the sacrum that will allow movement and a transfer of weight. When the left hemi-pelvis rotates to the right on a right oblique axis, it will tip forward anteriorly and move it ahead of the right. The sacrum rotates to the right on a right oblique axis and the centre of gravity also shifts to the right. This is mid-stance on the right with a right femur oriented outwardly and a left femur oriented inwardly (see picture below on the right).
Alternating reciprocal gait viewed from above, Postural Restoration Institute®. Copyright 2017, www.posturalrestoration.com
When this is reversed, the bones move back through neutral so that the right hemi-pelvis can advance and be anteriorly tipped and in a forwardly rotated state ahead of the left hip. The sacrum then rotates left on a left oblique axis and the center of gravity shifts to the left. This is mid-stance on the left with a left femur oriented outwardly and right femur oriented inwardly (see picture above on the left). For more details on the rotational patterns of the pelvis, lumbar spine and femurs and how they influence movement check out the Myokinematic Restoration course from the Postural Restoration Institute.
What happens if reciprocal movement as described above becomes limited due to repetitive overuse of particular muscle chains or postural habits? The body will indeed change its postural orientation and assume compensatory strategies such that the resting position of one half of the body does not match the resting position of the other. This is where “neutrality” has been lost.
Can the positional dynamics of these bones in the ring be changed? Absolutely. Namely, by addressing the position of the surrounding muscles. And this is key! If you restore the position of the muscles to their optimum, you’ll restore the position of bones and joints. It’s a win-win for all involved – the muscles and hence the joints will be in a proper position to generate force when they are asked to anticipate and participate in tri-planar functional movement.
The ultimate objective is to get reciprocal movement back where it is lacking in order to keep the right and left halves of the body balanced.