fitness

Strengthening of the abdominals and paravertebrals as a cure for back pain: is this true?

By Dr. Ilio Iannone

Body levers and muscle balance

Before answering this question it is important to make a premise about some fundamental concepts.

Since gravity is a vertical force directed downwards, man needs a force of opposite value that pulls him directly upward. This function is performed by the antigravity muscles, which in their activation make use of levers.

The intermediate fulcrum lever is the most used in physiology and, to be able to clearly explain what happens, it is necessary to resort to some elementary concepts of physics.

The triangle represents the joint support point (for example intervertebral disc), we consider that gravity (G) falls exactly on the point of support. For the system to be in balance the strength of the anterior (Fma) and posterior (Fmp) muscles must be equal. This system is called mutual tensions .

If G falls away from the point of support, the Fmp force must increase to safeguard the balance. For this reason the antigravity tonic muscles will be more numerous and strong in this district. In physiology this force is called erection force .

This essential organization causes the compression of the support point and is called the crushing component .

Demonstration

The proposed example corresponds to the middle fulcrum system of the dorsal region. The spinal, arranged on the opposite side of the support point, represented by the intervertebral disc, contrast the weight of the thorax.

We depict the bone with a lever.

The bone (or lever) is therefore subjected to:

Ft : action due to the weight of the chest

Fd : action of the disk on the bone

Fmp : muscle action

For equilibrium we will have: Ft + Fd + Fmp = 0

Or

Case1 Fd = -Ft-Fmp

In this first case it is deduced that the action of the disk on the bone is directed upwards. Reciprocally, the action of the bone on the disc is facing downwards; in other words, the bone rests on the disk and crushes it.

Case2 Fd = Ft + Fmp

In this situation it can be deduced that the intensity of the action on the bone on the disc is the sum of the weight of the chest and the action of the muscle.

These examples want to demonstrate how, in the specific case of the dorsal column, a situation of "unfavorable levers" is highlighted: the point of application of the posterior muscles is close to the point of support (vertebra), while the weight to be contrasted (thorax) is away from the fulcrum.

Conclusions

Given this information, it is possible to finally answer the initial question.

It is absolutely wrong to cure back pain by strengthening the abdominal and paravertebral muscles, as this type of work will lead to further impairment of the intervertebral disc. The more a muscle is rigid, hypertonic and shortened, the more the joint crushing component increases. Moreover, the more the weight is far from the point of support, the greater the antigravity muscle strength must be.

Another thing we should think about is the patient with dorsal hypercyphosis: also in this case, it is incorrect to strengthen the paravertebral muscles as the abnormal displacements of the masses anteriorly require a greater activity of the spinal muscles by increasing the joint crushing component.

Another mistake that is made is to consider the rectus of the abdomen as a lumbar de-lordosizer. The rectum of the abdomen has no relation to the lumbar spine, its action only causes the lowering of the ribs. As for its insertion at the pubic level, it is forgotten that the iliacs are related to the sacrum through the sacro-iliac articulation, for this reason the iliac bone moves independently without modifying the lumbar curve.

In conclusion, the posterior erector muscles must contrast, not only the weight, but also their complementary antagonists. The dorsal spinal muscles are opposite to the abdominals that lower the thorax and to the anterior muscle-fibrous system; their reinforcement causes a crushing of the intervertebral disc.