What is Repetitive Strain Injury?

The Repetitive Strain Injury is called with diffrent names, computer related injuries, cumulative trauma disorder.

The term "repetitive strain injury (RSI)" and "cumulative trauma disorder (CTD) mean the same thing - a muscle that has been used so frequently, doing the same motion, that is has become injured

Muscles are the reason we can move - when a muscle pulls on a bone, the bone moves. When the bone moves, we can walk, lift our arms, turn our head, wiggle a finger or a toe, in fact it even takes a muscle to blink an eye. Our bodies have 300 pairs of muscles for a total of 600 muscles.

All muscles have similar characteristics
•all muscles pull - they never push
•muscles go in a straight line, not around corners
•muscle originate on one bone and cross over a joint
•muscles merge into fibers called tendons
•the muscle tendon attaches to a bone
•when the muscle pulls the tendon, the bone moves


Muscles are made of many small fibers all lying next to each other, in some cases there are thousands of fibers, merging into the tendon. Each individual fiber works exactly the same way - it contracts and pulls on the tendon. Depending on the amount of strength needed to perform a task, a variety of the fibers will contract (shorten and pull) causing the action to occur. With this amazing system we have the strength to pick up a feather - or a heavy weight. The more fibers contracted, the greater strength expended.

There is a phenomenon called "muscle memory". When a muscle is contracted repeatedly, the brain registers it as needing to be shorter, and it changes the "set-point" of the muscle, making it shorter. Likewise, when a person stretches on a regular basis, the brain registers the change and lengthens the muscle. This lengthening releases the tension on the insertion points of the muscle, and eliminates pain that is caused by the short muscle, or its tendon, pulling on the bone.

When you do the same motion over and over, contracting the muscle continuously, several things happen:
1.The muscle fiber responds to "muscle memory" and permanently changes the muscle to the new shortened length. When this happens a problem occurs because the origination point and the insertion point remain the same, but the muscle is now too short to easily make the distance, so tension is placed on the muscle. While the tension can be at either end, it is more frequently felt at the insertion point at, or just over, the joint.

2.As the muscle fiber is contracting, but the insertion points remain the same, the fiber may tear, causing pain in the muscle.

3.The tendon may begin to tear away from the bone. When this happens the body sends bone cells to the area to hold onto the tendon. The build-up of bone cells forms a "spur". Nothing will stop the growth of the spur while the tendon is being pulled away from its insertion point.

4.If you try to remove the spur, without first releasing the muscle's tension on the bone, it will either quickly return, or the tendon will tear. This is commonly seen when the calf muscles are putting strain onto the Achilles tendon. As the muscles tighten, the tendon is pulled away from the heel, and a spur is formed on the back of the heel.

5.In the case of muscles that insert onto the spine, the vertebre are pulled out of alignment, and pressure is placed on the spinal cord and nerves. While there are many muscles that cause this problem, it is clearly seen in the case of the psoas (pronounced "so-as") muscle. The psoas originates on the lumbar (low back) vertebre, goes around the inside of the hips, and inserts into the front of the thigh bone. When the muscle contracts normally, you bend over or lift your leg. However, when the muscle is shortened by muscle memory, the lumbar vertebre are pulled forward, and the spinal cord is pressed by the moving vertebre. You now have low back pain.

6.Muscles can also trap a nerve, causing pain far from the site of the spasm. This is clearly seen in the case of the muscles of the neck, the scalenes. When the scalenes are in spasm they trap the bundle of nerves that become the nerves of the arm and hand. While the spasm is in the neck muscle, the pain and numbness is felt in the wrist and fingers. Until the spasm is released in the neck, the pain in the hand will not go away.

7.Tight muscle tendons can also trap a nerve, causing the burning pain and tingling common with nerve damage. This is most clearly seen when the flexor (forearm) muscles are contracted, causing the tendons to become taut, and the nerve to the hand is trapped by the tendons. You have all the symptoms of carpal tunnel syndrome, but all you actually are experiencing is the result of muscle tension impinging on a nerve.

8.When a muscle is pulling tightly on a joint, it is common for the joint to become stiff. Many people are told to strengthen the muscles that move the joint - but this is exactly the opposite of what actually needs to be done. The muscles need to be stretched, not strengthened. This is often seen in all the major joints - especially the shoulders, hips, knees and elbows. People will be told to lift weights, squeeze balls, cycle, or exercise to strengthen the muscles that move the joint. As they continue to contract the muscle even further, the joint becomes less and less mobile, and the person is told they have "arthritis", "bursitis", or they may even tear a tendon or ligament.

Repetitive Strain Injury can, and does, happen to muscles throughout the body. Every muscle spasm has its own referred pain area, frequently far from the source of the spasm. The spasms are commonly called "trigger points".