Maintaining Intervertebral Spinal Disc Health
Life is about finding balance and health-homeostasis. Spinal discs also need to be kept in fluid equilibrium, ‘Disc Hydrostasis’. Unfortunately, our lifestyles today put unreasonable stresses on our bodies in many ways, and our sedentary lifestyles, tension and stress coupled with extreme exertions also place further strain on our spinal discs.
Normal disc function – Disc Hydrostasis or Imbibition
Fluid moves in and out of the disc, a natural healthy process to help keep the discs flexible and responsive with tensile and ductile strength; healthy discs have the ability to stretch and deform under stress, but to return to normal without being strained. Spinal discs have no direct blood supply, so they need to absorb the nutrients by changes in pressure, and through a process called ‘imbibition’ – the absorbance of fluids by a solid matter.
The lubrication process occurs by a sort of flushing mechanism, when load is applied and then removed from the tissue repeatedly. Activities that involve repeated smooth joint movement, such as stationary cycling and walking, can promote this lubrication process without creating too much stress on injured cartilage tissue.
Vary activities and keep active for healthy discs!
The key message here is that we need to avoid sitting too long. Vary your activities, rest your back lying down sometime during the day if possible, avoid slouching, and exercise gently and regularly. I cannot stress this enough.
Why we are taller in the morning than the evening
The disc heights change with the variation in fluid content. When we sleep or rest our back lying down, our spines no longer have the muscular contractions and gravitational & compressive forces that occur during the day. The discs replenish their fluid content and nutrients to stay healthy.
At Night: ↑ disc height ↑
The increased fluid in the discs increases our height up to about half an inch in the morning, which is similar to when an astronaut travels to outer space, where they can gain up to two inches of height! The discs also retake nutrients, oxygen, glycogen, platelet, growth and healing factors to repair and maintain disc health.
During the Day: ↓ disc height ↓
Our spines loose height as the gravitational the compression on the spine forces the fluid out of the discs. This process is healthy to an extent; the metabolic waste in the disc can be eliminated, as well as scar tissue, damaged cells, debris and lactic acid.
Reduced disc flexibility as we age, or with injury
As we age, the discs begin to lose their height and fluid content, so that in old age there will be much less of a height change, as with any damaged or worn discs. The discs, however, will generally become more stable with fibrous adhesions and scar tissue and whilst not as flexible as in our youth, they can still support and give some degree of movement to allow us to carry out our daily activities.
Muscle contractive forces affecting disc hydrostasis
Muscle tightness and posture has a huge influence on increasing the compressive forces on the spine during the day, increasing the fluid loss.
If we do not relax at night, are tense or sleep hunched or taught, we do not allow the compressive forces to release, and the discs cannot then regain the essential fluid content they need to self-repair and remain healthy.
Types of Intervertebral Disc Degeneration
The difficulty for our spinal discs is that we place too much stress and strain on them and do not allow them to rehydrate and heal as they need. Below shows the types of disc degeneration. Although two thirds of people have back pain at some stage, it is now shown on MRI scan that people with back pain have more degeneration and wear in the discs and spine. Degenerating discs are usually the result of lack of nutrient flow into the spinal discs. If the discs herniate, bulge or protrude, they can put pressure on the spinal nerves, causing sciatica in the leg or arm pain from a cervical or nerve disc injury.
Sitting too long, or badly
Too much sitting puts compression forces on the spine, which is exacerbated by our sitting positions and commonly lack of exercise or resting the back
Lifting wrongly
Clearly the discs can be strained if we lift wrongly, or lift objects that are too heavy! We put too much compression, shear or rotational forces through them.
Exercising when our discs are in a weakened state
It’s all too common that we may sit too long, compress the spine, the muscles are tight, the discs are dehydrated from the sitting and then we go and exercise too hard to make up for it all!
This is a very common reason for overstraining the spine. I talk about warming up for exercise and the dangers of over-exercising.
Smoking and disc degeneration
One study showed smoking can restrict the blood flow by damaging the small arteries on the sides of the spinal discs which in turn inhibits or stops red blood with oxygen and nutrients from reaching your discs, thus accelerating the disc degeneration.
Degenerative disc disease
This causes the discs to dry out and loose height as we age, or with injury.
Pressure on the discs and may cause a bulging or herniated disc. It can lead to nerve compression, commonly with leg or arm pain. In addition, cartilage wear leads to facet joint degeneration or wear and tear.