Vertebral Loads: The studies of Alf Nachmenson

As shown in the table, assigning a value of 100 to the load recorded between the third and four lumbar vertebrae while standing, and expressing the other loads as a percentage of this, one can note how the inter-disc pressure decreases by 75% when lying on one’s back, and increases by 40% when sitting.

The position of greatest risk are those bending forwards, both from sitting and standing. These cause an increase of the disc pressure from 50% to 175% depending on the weight carried in front.

These studies show how some positions adopted in daily life can be damaging for the back ( in the car, at work, during housework etc.)

It must be said that a healthy vertebral column is able to withstand the strains due to the various positions indicated in the table. Problems arise when one must maintain a certain position for a long time. Sitting for 8 hours at a time or carrying out work involving bending forwards all day, can result in over pressure of the discs which can give rise to protrusions and hernias of them.

I advise trying to vary as much as possible the position which one usually assumes: es. people who sit for many hours should frequently stand up and walk around.

I consider this study to be of great use in that it shows which positions can increase the risk of compression of the discs, and therefore is of great help in the prevention of the back pain.