This article was originally published in Positive Health issue 58 – November 2000

“Whether the lower back should be flexed (bent forwards) or extended (arched) is the latest controversy. Both approaches may be right or wrong depending on the patient’s specific problem…”, says René Caillet, an MD., in Understanding your Backache.

According to my understanding of the biomechanics of the spine, both approaches are wrong. I explained last month why I think slouching (bending forwards) is not good for the back. Let me explain now why I think arching is no better, if not worse.

First, we must clarify the meaning of some words. René Caillet uses ‘flexed’ as synonymous with ‘bent forwards’, and ‘extended’ with ‘arched’. This is an incorrect use of these words, which inevitably leads to erroneous conclusions about the workings of the spine and its treatment.

‘Flexing’ is a generic term: the spine, for example, can be flexed forwards, sideways – or backwards. If, from the upright position, the spine is flexed or bent backwards it will be arched or concave, but certainly not extended. The word ‘extended’ means, in this context, ‘straightened or stretched out’. To say that an arched spine is extended, i.e. straightened, defies reason.

If you don’t know it already, I would like to introduce a medical term which will prove useful for our discussion, namely ‘lordosis’. This word, from the Greek, simply means ‘bent backwards’. In medical parlance, lordosis refers to the inward curvatures of the spine. The human spine has two normal or physiological lordoses: the cervical and lumbar. However, the term lordosis is usually used to designate an abnormal inward curvature causing an excessive concavity of the back. So, an abnormally arched, a bent backward or incurved segment of the spine is said to be lordotic.

Kyphosis, the opposite of lordosis, designates the bump in our spines, and is normally situated at shoulder-blade level. Think of it as the point of junction between the two lordoses. The size of the kyphosis is governed by the size of the lordoses: the deeper the latter become, the more prominent the former. Thus, the Dowager’s hump is the result of excessive lordosis. Although the hollows and bumps have a specific, reserved place in the spine, they can, in certain conditions and positions, leave their elective site momentarily, or permanently as in the spinal shape known as ‘reverse curves’. An example of reverse curves is where the lower back is rounded instead of being concave.

The champion of the use of arching (bending the spine backwards) as a treatment for bad backs is Robin McKenzie, a physiotherapist. His therapeutic approach seems in complete contradiction with the one devised by François Mézières, another physiotherapist who, following empirical discoveries, revolutionized and turned her profession topsy-turvy.

To Mézières, the lordosis is the primary source of all our distortions and musculo-skeletal troubles. Lordoses are the arch enemy of Mézières; she is the enemy of the arch. Accordingly, she spent most of her working life cursing and curbing lordotic curves. To McKenzie, the loss of the lumbar lordosis, mainly through sitting or bending forwards wrongly, is the main cause of back pain; most of his therapeutic efforts consist in arching the lower back of his patients. As usual, the specialists disagree and the non-professional does not know who to believe.

Instead of believing anything or anybody, let’s study the body mechanics. The S-shape spine is subtended by powerful muscles that can rotate it and flex it backwards or sideways. Their chief action is postero-flexion, i.e. arching. These muscles always end up too short and too tight, thus deepening the lordoses. But the muscles at the back of the legs, closely linked to the back muscles, also tend to shorten and to affect the shape of the spine. For example, during sitting or bending forwards the hamstrings pull the pelvis backwards, causing the lower back to become rounded. On these occasions, the lumbar lordosis has not totally disappeared; it has only been displaced upwards. Even in inveterate slouchers, or in the reverse curves cases, the lordoses still predominate largely over the kyphosis.

To get to know your lordoses, stand against a wall with the back of your skull and sacrum touching it. In this position you can probably feel that, between these two extremities of the spine, only a few vertebrae (from one to four) are in contact with the wall. Below and above this region are big gaps: these are the lordoses.

When the posterior muscles shorten there is not enough space to accommodate the normal shape and curves of the spine: the curves increase and/or leave their normal place. It is true that a lower back that is frequently rounded will suffer from strain and damage. But the solution is not a regime of arching exercises, since it not only doesn’t address the primary cause (bad use and bad shape) but, moreover, it will shorten the back muscles to an even greater extent.

As usual, the solution is to remove the cause. Firstly, one has to stop misusing oneself; secondly, one has to regain normal spinal curves by lengthening the muscles that subtend them. To achieve this, one has to stretch out the whole spine along its length. Pushing the bump in by arching the spine, which means working in a right-angle direction to the spine, does not and cannot lengthen it and its muscles. On the other hand, it surely can aggravate the lordotic state of the spine, the very cause of back pain.

By taking care of only part of the spine, the ‘arching treatment’ is a partial and symptomatic approach that does not address the cause and may even aggravate it. Arching often means aching!