The spinal engine is a term given to a phenomenon seen in nearly all-natural human movement, but especially in walking and running. The term describes the spines' ability to create and originate the movements of walking and running without the use or input of the legs and arms.
Whereas it used to be assumed that the legs in particular, are what establishes and maintains human gait movements, experiments by Serge Gracovetsky in the 1980's showed that even those who had both arms and legs amputated could still “walk”. This walking was done on the sit bones utilizing only movements of the spine and pelvis.
This meant that human gate motions do not even require arms and legs, and that the use of the appendages is actually an extension of the movements created by the spine. In a sense, it was determined that the spine is the primary engine behind walking and running and not the legs and arms, as had previously been believed.
However, the arms and legs were designed to be excellent extensions of the spine and to feed into the spinal engine, make it more efficient and making humans capable of upright locomotion.
During walking and running motions, the spine rotates to allow the pelvis to rotate, bringing first one leg in front and then the other as the spine rotates back the other way. In order to make this movement more efficient, the upper spine rotates the opposite direction of the lower spine. This counter rotation serves to load up the oblique sling of muscles on one side of the body as it's stretched to its end range of motion.
This loads the tendons and fascia with elastic energy which will recoil after reaching end range. This elastic energy assists the spine in its need to counter rotate the opposite way during the next step. The arms and legs, in this sense, are adding momentum to the spinal rotation as they swing through their gate cycle, effectively pulling against each other to load up the core like a spring, releasing it with each new step to propel the spine into the next counter rotation.
When done properly the spine rotates and counter rotates with very little effort, creating very efficient walking and running mechanics. This requires proper timing of the counter rotation, who's rhythm can often become out of sync with postural issues and lower body injuries. The postural issues can creep up in any portion of the spine, but the most common rhythmic issues tend to pop up in the lumbar spine.
A good way to try and improve your gait rhythm is to attempt to walk in cadence with the steady beat of a song. This will even out the timing of your steps so that one foot is not making contact with the ground longer than another, which is so commonly seen in postural issues. "Up Town Funk" by Bruno Mars is a great example of a song with a steady and clearly audible rhythmic beat, with a timing nearly identical to a lively walk.
The timing of the steps is important for another reason as well. Each step creates a shock wave that travels up the legs and into the hips and spine. This shock wave pushes on the bottom of the spine and sends a compressive wave through the spine itself, causing the vertebrae to attempt to straighten. The vertebrae straighten because the compressive force of the foot strike forces the facet joints of the spine closer together, which can only happen if the spine de-rotates.
Essentially, this means that the shock wave of the foot striking the ground assists the spine as it de-rotates and begins to counter rotate in the other direction. It's one more way in which the body saves energy and creates a more efficient walking and running pattern.
When the timing of the steps is off, the shock wave travels through the spine at the wrong moment in its rotation. Instead of helping to de-rotate at the appropriate moment it will instead create a jarring effect on the spine which the muscles of the core have to compensate for. In the short run this makes running and even walking, tiring and inefficient. In the long run this can damage joints and lead to serious overuse injury.
The Power of Levity
The spinal engine, when not hampered by deformed posture, injury or off beat gait rhythm, will work so efficiently that walking and running begin to feel nearly effortless. The posture remains tall while the body moves forward easily, with smooth and graceful motion.
In this state the spine works so effectively that it ceases to be held up by muscular effort and instead is held upright by the balanced forces of the fascial tissues (tensegrity systems) that surround it. This state is often called levity, as it feels like one is naturally uplifted by an unseen force which is easily opposing gravity.
This is also a natural reaction to the emotion of joy. Joy creates an unstressed and highly efficient biochemical environment inside the body. So efficient in fact, that it energizes the body to the point of literally uplifting the posture into a state of levity. The opposite of this is seen in depression, where the body is a toxic soup of stress hormones causing very low energy levels and a very drooping and lifeless posture.
The uplifting power of both joy and the spinal engine can be taken advantage of in daily life as well as in training. Causing levity through the correct use of the spinal engine will help create feelings of ease, grace and joy, increasing the very fulfillment of the life experience itself. The opposite is also true, finding reasons to feel joyful throughout the day will also energize the body and help create levity. Levity will then empower the spinal engine to do its work properly, increasing movement efficiency, decreasing the likelihood of injury and increasing one's energy levels throughout the day.
If you would like to implement the proper use of the spinal engine into your life but you feel your current spinal posture might be an issue, check out my 3-part blog article all about correcting the most common issues of the spine.