All About Your
Back
Today back pain is one of
the most common of all physical complaints in the world. About 70 to 90% of men
and women in the U.S. have had or will have a least one bout of incapacitating
low back pain. Back pain contributes to lost work time and may cost as much as
$100 billion annually (if lost productivity is included1).
Doctors generally agree
that most back problems are caused by stress or by weak muscles. We need strong
back , stomach, and hip muscles to resist gravity and to hold us up. As
societies around the world become more mechanized and computerized, they have
also become less exercised. We lock ourselves behind desks and in front of
computers. When we sit, our back muscles hold us erect, but our stomach and hip
muscles are inactive. When they are not exercised, stomach and hip muscles
become weaker, putting a painful strain on the back muscles. Sitting places
higher loads inside the lumbar disc than standing (between 150% to 250%
depending on posture).
The condition of your back
is very important to your health. A better back can lead to a better body.
Anatomy of the Back
Briefly explained, your
spine is made up of the following components:
 1)
Vertebrae - the bones that make up your spine
2) Nerves - your entire nerve system runs through your spine
3) Discs - spongy material that separates your vertebrae, allowing the
nerves to run between each bone segment. Discs act like shock absorbers and
allow the spine to flex.
Each vertebrae is held in
its proper place by three different kinds of soft tissue-discs, ligaments, and
muscles. Almost all back problems are related to the dysfunction of one of these
three. To understand the sources of your particular back problem and/or how to
prevent back pain, it helps to understand the anatomy of your spine.
 The
natural curves of the spine are vitally important for giving your back strength
and resilience. There are 24 vertebrae in your spinal column. The lumbar
vertebrae are approximately two inches in diameter reflecting their
weight-bearing role. The cervical vertebrae are smaller, since they must support
only the head. Facet joints are located in pairs on the back of the spine, where
one vertebra slightly overlaps the next. The facet joints guide and restrict
movement of the spine. To the rear of each vertebra is a hole and when the
vertebrae are stacked up, these holes form a continuous channel which holds the
spinal cord.
The spinal cord provides a
vital link between the brain and all body functions below the neck. Spinal
nerves emerge from the spinal cord through gaps between the main body of the
vertebrae and the facet joints. One frequent cause of back pain is a worn facet
joint, which can result in a pinched nerve. Therefore, it is very important to
keep your vertebrae in good shape.
 This
drawing shows a normal disc. The main function of your discs is to act as shock
absorbers and provide separation between each vertebrae. The outer layers of
your discs are formed from tough cartilage. The inner core of your disc is a
jelly-like nucleus.
In total, your discs account for one-quarter the length of your vertebral
column- 4.50" to 6" (12 to 15 cm) for most people. The disc acquires its
nourishment through fluid-attracting and fluid-absorbing qualities of its
jelly-like nucleus.
 With
no blood supply of its own, the disc is dependent on sponge action for
attracting and absorbing nutrients from adjacent tissues. During non-weight
bearing activities (sleeping) the discs expand as they soak up fluid, increasing
the length of the spine by as much as one inch overnight. During weight bearing
activities (sitting, standing, exercising), this fluid is squeezed back into the
adjacent soft tissue.
Your vertebra are
supported and moved by many different muscles. Muscles are used for three basic
functions; support, movement, and posture control. If muscles are tight or weak,
they create or worsen back pain. Joints are controlled by at least two sets of
muscles, flexors which bend the joint, and extensors which straighten it. In
addition, most joints have rotator muscles that twist and rotate your bones.
Good posture is only possible if the flexors, extensors, and rotators are in
proper balance.
Your paraspinal muscles
(which run parallel to your spine) rotate your spine, bend it backwards, and
sideways, and influence posture by creating and maintaining the curves of your
spine. Your erector spine muscles are involved in movement and run the length of
your spine. These muscles help you to bend over by resisting the force of
gravity, and to straighten up by contracting and exerting great compressive
force on your spine.
Your abdominal muscles
play an important role in helping to support the spine by maintaining pressure
inside the abdomen. This pressure is an essential measure of counter support to
the spine.
Your psoas muscles (hip
flexors) are a large group of muscles in the abdomen. These muscles help to flex
your hips when walking or climbing stairs. They play an important role in
maintaining posture for sitting and standing.
Intravertebral joints are
supported by ligaments, tough and inelastic fibers which support the spine and
hold it together by allowing only a limited range of movement in any one
direction. Ligaments require regular movement and loading, otherwise they will
eventually become stiff and weak.
Summary
- There are 24
vertebrae in your back which encase your spinal cord.
- Spinal nerves run
through each vertebral joint in your spinal column.
- Your discs act as
shock absorbers.
- With no blood supply
of their own, discs depend on sponge-like action to soak up nutrients.
- Muscles and ligaments
require regular movement in order to maintain flexibility.
Back Pain
Since every nerve root leaves the spine through a space between the vertebrae,
discs that are plump and contained in their ligament "wrappers" are necessary to
keep the nerve roots free of pressure and your body free from pain.
Stress and tension can cause muscle spasms in the back, neck and shoulders,
as well as headaches and other problems. Tense muscles produce spasms and pain
by reducing the supply of oxygen and by reducing blood and lymph flow, allowing
the accumulation of waste chemicals in the muscles.
A back injury is usually not caused by one single incident. The extent of
your injury is determined by how much wear and tear your back has been through
prior to the injury. Over a lifetime, many minor stresses or irritations add up
to cause damage that can gradually weaken and stiffen your spine, setting you up
for a significant injury. Many doctors agree that main causes of back pain are:
Gravity, Weak Back Muscles, Muscle Imbalances, and Poor Flexibility.
Gravity  To
understand just how dramatically gravity affects your spine, try this exercise
at home: Measure your height in the morning and then measure your height again
at night. You will be 1/2" to 3/4" shorter at the end of the day because of the
compressive effects of gravity on your spine. During weight bearing activities
(sitting, standing, exercising), fluid is squeezed out of your discs and into
the adjacent soft tissue. This lost of moisture results in height loss by the
end of the day!
During non-weight bearing activities (sleeping), the discs
expand as they soak up fluid increasing the length of the spine. However, you
will not gain the full 100% of the height lost back. This is evident in the fact
that as a baby, your discs are 90% water. By the time you reach 70 years of age,
your discs are only 70% water! Over a lifetime, this loss of moisture causes
thinning discs and you will lose ‡" to 2" in height!
Loss of height due to gravity would be easy to live with if
it was the only result of thinning discs. However, another result of thinning
discs is worn facet joints due to increased pressure. The joints can become
irritated and inflamed, and the capsule of lubricating fluid that surrounds each
joint might swell and press on a nerve root.
How do activities affect the amount of pressure on your
discs?
 Our
daily activities (running, sitting, weightlifting) and the force of gravity
places pressure on your discs. For example, sitting places 50% more pressure on
your discs than standing. Sitting and leaning forward (i.e., typing at a
computer) places 150% more pressure on discs than standing. The average person
will spend 16 hours (2/3 of your life) day sitting or standing.
What evidence shows that gravity is a major cause of
thinning discs? Astronauts grow in space! After 84 days in space (a gravity-free
environment) astronauts grew 2" in height. During twelve weeks in orbit, their
discs had continued to take moisture from the blood stream, but with no
gravitational pull to squeeze moisture out, the discs remained plump, making
their spines longer, and themselves taller. In fact, space suits are designed to
accommodate the extra 2" spinal stretch. After a few days on earth (a gravity
environment), they returned to their normal height.
How can Inversion reduce the effects of gravity?
When you invert and relax, your body can stretch up to 2
inches. "Muscles relax quite quickly in the fully inverted position, and the
length of the spine measurably increases after only a few minutes. Some of the
lengthening effect is gained from re-absorption of fluid into the center of the
disc. Used over a longer period, this may delay the degeneration process that
occurs due to 'drying out'" (Beating Back Pain, Tanner).
Image 1. Supine - Lumbar curve maintained, posterior
erector muscles contracted (shortened), intravertebral disc pressure, and psoas
exerts pressure on spine.
Image 2. Pre-Inversion - Lumbar curve reduced,
muscular relaxation, and pressure of psoas muscle decreases.
Image 3. Seated Inversion - Joint spaces widened,
pain relief, intravertebral disc pressure reduced, and musculature stretching.
Summary
- Over a lifetime, you will lose, 1/2" to 2" due to
thinning discs.
- Since your discs act as shock absorbers, thinning
discs can cause intravertebral joints to become irritated and inflamed.
Gravity is a major cause of thinning discs. Inversion reverses the effect of
gravity on your spine.
- While inverted your spinal length increases partly due
to the reabsorption of moisture into the center of the disc.
Weak Back Muscles
 It
is estimated that 60%-70% of all back pain is the result of muscle strain. Your
musculo-skeletal system needs a basic level of strength and endurance in order
to protect itself against back pain. Your muscles need a good supply of blood
and energy in order to be maintained at peak performance. Poor posture or muscle
spasms can deprive the cells and tissues in your back muscles of a good supply
of blood and oxygen.
For example, when you sit and bend forward (i.e., typing at a
computer) two of the three muscle groups which support your back (abdominal and
hip flexors) are inactive and, therefore, being detrained (weakened). If this
posture is maintained, muscles will become painful, weak, less elastic, and
shortened.
Muscle Imbalance
Often muscles acting on a joint are out of balance. For
example, the flexors may be tighter and shorter than the extensors, so that the
joint cannot be fully straightened; or the muscles that rotate the joint in one
direction may be stronger than those that rotate it the other direction (i.e.,
one-sided sports like golf). These unequal forces make the joint weaker and more
vulnerable. Parts of the bone surfaces bear more weight than they should. This
imbalance can cause pain.
Gently stretching your back muscles, through inversion,
can help increase the supply of blood and oxygen to your back muscles. With a
regular inversion program of stretching and strengthening, the muscle groups can
be brought back into balance.
Summary
- Muscles need regular exercise in order to maintain
posture.
- Various one-sided activities (i.e. golf) can cause
muscles to be unbalanced
- Inversion provides a gentle stretch to help increase
the supply of blood and oxygen to muscles.
- Inversion can help bring muscle groups back into
balance and thus improve body alignment (posture).
Poor Flexibility
Muscles and ligaments require regular movement, otherwise they will become
stiff and inflexible. As you age, your discs become thinner, bringing the
intravertebral joints closer together. The ligaments that support the spine
become more slack and joints become looser. It is like a worn machine with a
loose drive belt or pulley. Any undue strain may throw something out of gear.
Throughout your life you obtain strains by bending the spine too far, placing
too much load on the spine while in the bent position, or bending repeatedly.
Ligaments have a limited blood supply and thus do not heal easily. Sometimes
they fail to heal completely, thus leaving scar tissue. Scar tissue is not as
strong or flexible as regular ligaments or muscles and leaves the area stiffer
and weaker. This is how your back ages and becomes less flexible. Without
regular loading and movement, ligaments can become stiff, which may increase the
risk of injury.
Unless appropriate exercises are performed to restore normal flexibility, the
unhealed tissue may produce a continuous source of back pain and/or stiffness.
Simple, gentle loading and movement can help scar tissue become more flexible
and more strong, or absorbed and replaced by more normal ligament and muscle
tissue. This strengthening can help to prevent a re-injury. Although there are
exercises to stretch parts of your back separately, inversion helps to gently
load and move all the ligaments encasing your spinal column at once.
Summary
- Muscles and ligaments require regular stretching to maintain normal
flexibility and strength.
- Inversion helps to gently stretch muscles and load ligaments.
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