The Correct Way To Do Deadlifts. Sarah Key On How To Avoid Back Pain 

It's important to know the correct way to do deadlifts because injuries are legion (back pain and deadlifts go hand-in-glove). Even though they are seriously strengthening for your gluts and long spinal muscles, deadlifts are seriously bad for your back. It's all about spinal stability related to spinal biomechanics and the problems brought on by lifting with the lower back too arched. 

The Correct Way to Do Deadlifts Minimises Shear Forces Across the Lumbar Segments

When standing normally, the lower two lumbar spinal segments (L5 and to a lesser degree L4) have a tendency to slide forward because they are sitting on the forward-sloping sacrum. Shear is unwanted. Even the tiniest degree of uncontrolled shear creates a sickening jolt of pain that can be the beginnings of a lifelong back-saga. 

To Understand the Correct Way to Do Deadlifts You Have to Understnnd a Little Bit of the Anatomy of the Back

Doing Deadlifts Correctly Safeguards Spinal Stability, Which in Turn is Influenced By...

• Load-sharing between the intervertebral discs & the facet joints
  
  
• The active role of the muscles, both trunk and spinal
  
  
• The passive or restraint role of the spinal ligaments

Doing Deadlifts Correctly Optimally Loads the Intervertebral Discs

The intervertebral discs are at the front of the spine. They work as tense bags of fluid that thrust the vertebrae apart, while also shock absorbing to contain errant movement between the vertebrae. They work best under pressure - the higher the intradiscal pressure, the stronger and  more whippy the spine is - and the more secure under load. Doing deadlifts correctly increases the holding pressure of the lumbar discs by pulling the tummy in hard and rounding the lower back. 

The Correct Way to Do Deadlifts Minimises 'Wobble' of the Spinal Segemnts Under Load

Arching the lower back takes the pressure off the discs, which can allow errant movement to creep in. This is felt as a definitive, deep-seated happening deep inside the back - a movement, a click, a ripping sound - which despite being relatively minor, also in a peculiar way feels sinister. It brings on a troubling 'Uh-oh' feeling that's somehow deeply alarming. This minor shearing strain targets the outside of the disc - the annulus fibrosis, or the disc wall - and strains the 'outer skin' which is the only part of the disc with a nerve supply.  Being tensile, this outer annulus is termed 'ligamentous' and so sprain here is like a ligament sprain anywhere else in the body. 

You can see from the diagram that nerve filaments (in black) supply sensation only to the very outer layers of the disc, slightly more at the back. The outer disc is tensile and sensitive to yanking - even minor yanking - just like say the lateral ligament of the ankle when you roll over on it - by unguarded movement of the spinal segments under load. The bigger the load the greater the strain mishap. 

The Correct Way to Do Deadlifts Avoids Overloading the Facet Joints at the Back of the Spine

The facet joints are bone-to-bone junctions at the back of the spine. They are not load-bearers; they are movement controllers, reducing twist through the lower back and acting as a brake on bending. They do this by controlling the forward travel of each upper vertebrae on its neighbour below. By lifting with an arched back you harm the facet joints  by making them bear load. 

The Correct Way to Do Deadlifts Avoids Excessive Bone-to-Bone Contact of the Facets When at the Same Time the Disc is Depressurised

Unlike the intervertebral discs, the facet joints are not built for load. The two opposing joint surface are covered by a protective glistening buffer of hyaline cartilage that cushions the bone-to-bone contact. In normal standing posture their contact is fleeting, bearing only about 16% of load.

With the hyper-extended, or excessively arched posture of deadlifts the facets can be destructively compressed, while at the same time the lack of pressure in the disc means more 'rattle' of the segment. This micro-movement targets the synovial joint structures of the low lumbar facets and leads to joint strain. 

Also unlike the discs, lumbar facet joints have a highly sophisticated nerve supply. They are wired for pain and easily pick up messages when the joint is hurt.  Traumatic compressive forces on the facets are added to by the bowstring action of the long spinal muscles working hard to compensate for the reduced holding pressures of the disc.

You can go to the page Are Deadlifts Bad For You? to see more on the correct way to do deadlifts to minimise damage. You can also watch in depth what it is in the back that causes pain. Read more about this video of Sarah's.