Despite the name, spinal column is not straight, but rather S-shape curved from lateral view. Upper back is naturally kyphotic or rounding to give space for the lungs, whereas the cervical and lumbar spine are lordotic or in a natural backbend. Just as there are many body types and shapes, there are also many different angles of the spinal curvature. If in a yoga class we ask you to ‘straighten the spine’, it simply means to stand tall or to return the spine to its neutral position still honouring its natural curvature. And this of course means a different curvature for everyone.
If the spinal curves have different angles for everyone, how do we know whether our posture is anatomically correct? To understand the natural curves of the spine, we need to understand the possible pelvic positions. In sagittal plane, the pelvis can be in three different positions; neutral (a), posteriorly (b) or anteriorly (c) tilted. A neutral pelvis allows the spine to be neutral, whereas a posterior pelvic tilt would flatten out the natural lumbar curve and an anterior pelvic tilt would require excessive lumbar lordosis to keep the spine upright.
How can we tell the difference between an appropriately lordotic lumbar curve with a correct force transfer and a hyperextended lumbar curve that can get compressed under load? There are of course various orthopedic assessments that would determine the angle of the pelvis and find its neutral position, but if you’d like to try this at home there is an easy weight transmission test you could try.
Stand tall in your natural position without trying too hard to realign your spine. Then ask a friend to place one hand on each shoulder and pull the shoulders directly down (not backward or forward). Check where you feel the weight. If you feel the weight distribution on the shoulders and feet, but nowhere in between, the weight transmits correctly though the spine and sacrum into the legs. But if you feel pressure in the lower back, the weight doesn’t go though the spine but straight into it. In this case the most common cause would be an anterior pelvic tilt. Over time this posture could cause lower back pain.
In her book ‘Making Connections’ Peggy Hackney introduces a tool for a dynamic sense of alignment. Stand in Tadasana and imagine a figure-8 loop around your pelvis and ribcage viewed from the side. Start tracing the figure-8 from the lower back towards the tailbone, then from the pubis up towards the navel. Continue tracing the figure-8 through navel to the upper back towards the head, and finally down from the sternum towards the navel (image 1).
This is an easy tool to keep the lumbar spine long and the bottom of the sternum ‘hooked down’ towards the navel to prevent the lower ribs splaying out when opening the chest. This imagery doesn’t actually mean that you would maintain a neutral spine at all times, but rather remind to maintain some length in the lumbar spine and some tone in the abdominal wall to keep the lower ribs contained in all spinal positions. On the other hand, in case of an anteriorly tilted pelvis, the direction of the figure-8 loop is reverse. The reverse figure-8 loop shortens the lumbar spine as shown in image 2.
If you had pressure in your lower back in the previous test, remember to unlock your knees, as locked hyperextended knees push the head of the femur forward, which tilts the pelvis anteriorly. After softening the knees, trace the figure -8 in your mind to bring the pelvis back to its neutral position and repeat the same test again. If you now feel a new length and lightness in your lumbar spine, try to remember to unlock the knees and recreate the figure-8 as many times as day as needed, and use it in your yoga practice.