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
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.
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.