This article was originally published in Positive Health issue 101 – July 2004

In the bodywork and fitness world, the concept of core muscles and core strength is a fairly recent but already well adopted one, in spite – or because – of its lack of scientific rigour. Just when we had decided to dispense with the harmful corset, it is coming back in a muscular form. Most people are buying into the idea that they need to wear a muscular corset, a girdle of strength whose fabric derives from the elusive core muscles. This belief stems directly from the idea that we are suffering from weakness, from a generalized lack of muscle tone. Nothing could be further from the truth.

The idea of a core applied to the body is not altogether a bad one but, in my mind, it would be very different from the popular conception: it won’t be comprised of the same muscles and their tone would need to be decreased rather than increased. Let me explain.

F Mézières urged her colleagues to study the human animal in the manner of a palaeontologist, by ‘dividing’ the body into a hindquarter and a forequarter. The forequarter comprises the head, neck, upper limb, shoulder girdle and the spine down to T7 (level of the inferior angle of scapula). The hindquarter is made of the spine from T7 to the coccyx, the pelvic girdle and the lower limb. All the elements of a quarter are interdependent. Some muscles and nerves are specific to each quarter whilst five muscles link the forequarter with the hindquarter.

If, in the past, some bodyworkers, such as J Pilates, believed that the normal spine should be straight, nowadays everybody, except maybe a few eccentrics, accepts that the spine is a naturally curved affair made up of two lordoses (concavities) and one kyphosis (convexity). The cervico-thoracic lordosis runs from the occiput to T4 and belongs to the forequarter; the thoraco-lumbar lordosis, from T7 to the sacrum belongs to the hindquarter. These two lordoses are divergent: the upper one ‘looks’ upwards; the lower one, downwards. The meeting point of the lordoses forms what is known as the kyphosis, a short segment made of only a few thoracic vertebrae.

Because of its protruding nature, it is usually the kyphosis (round back) that worries and preoccupies both the therapist and patient. However, to Mézières, it is the departure of the lordoses from their physiological, normal limits which is the enemy of good shape. The increase of the lordoses is the origin of most of our distortions and misshapes and, as a consequence of our musculo-skeletal ills, since shape conditions function. Apart from congenital causes, the deepening of the hollows in our backs is induced by a shortening of the muscles that subtend them in the same way that tightening the string of a bow would increase its curve. Now, our lordoses are especially well-endowed muscularly. The lordoses have muscles running in the front as well as the back of the spine as if they were contained in a muscular sheath. Our kyphosis does not have this privilege since there are no muscles attached to the front part of the spine from T4 to T11. Lordoses have more than one string to their bows!

The anterior part of the upper lordosis is covered by a small muscular chain (three muscles) running from the occipital bone to T4. When shortened, these muscles, in spite of being on the convex side of the lordosis, increase it instead of flattening it. There is the same configuration with the lower lordosis, where the anterior part of the thoraco-lumbar spine is the point of attachment to another muscular chain made up of the diaphragm and ilio-psoas muscles, which, when shortened, increases the hollow in our lower back. The small muscular chains situated in front of the spine act in synergy with the big one running posteriorly to it. So we can see that our lordoses are covered, front and back, by muscles hugging them in a tight embrace that conspires to gradually, or sometimes rapidly, deepen our hollows and by the same token gives us a lot of muscular grief. This is why our neck and lower back have a propensity for various pains and pathologies.

In this anatomical concept, the two lordoses are the true cores of the body; the muscles which clothe them are the core muscles. To borrow the corset metaphor, it’s clear that we need to loosen our stays rather than stiffen them further, if we are to achieve optimum comfort and good function.