Repetitive Strain Injury and Myofascial Pain Syndrome

During the last few years I have followed the postings to online Repetitive Strain Injury (RSI) discussion lists with considerable interest, and have occasionally offered some suggestions for myofascial pain sufferers. Scott Wright encouraged me to write this FAQ to assist in understanding myofascial pain, a syndrome that is still quite a mystery to many people including physicians, chiropractors, and therapists.

When muscles are overused, fatigued, and strained, trigger points form in the muscle and its associated fascia. Fascia is the variable thickness connective tissue that holds muscle fibers together, attaches muscles to bone, and holds bones together. These trigger points can be felt as small knots within taught and ropy bands of muscle. The trigger point causes the tightness along the muscle fibers, thereby forming the taught or ropy band.

Each trigger point generates two pain patterns, whether the person is conscious of it or not. One pain pattern is localized, causing local soreness and tenderness, while the other may be local or distant. The distant or referred pain pattern will be interpreted by the brain as numbness, tingling, burning or aching. All trigger points may generate some degree of these pain patterns all of the time. Trigger points may also cause the muscle to cramp.

Trigger points may be classified as active, latent, or satellite.

An active trigger point is a focus of hyperirritability in the muscle or its fascia that generates pain. It will usually cause more pain with use of the muscle.

A latent trigger point is less tender than an active trigger point, commonly producing pain with applied pressure. It will generally restrict motion, prevent full lengthening of the muscle and cause weakness without atrophy (atrophy: muscle wasting or smaller in size). A latent trigger point does not usually generate a noticeable level of pain.

A satellite trigger point develops within the zone of referred pain from an active trigger point. When a trigger point is active and refers a strong level of pain to another area of the body, muscles in this other area develop "satellite" trigger points. In this fashion a localized pain pattern may spread to other and larger areas of the body.

Repetitive strain injury causes formation of new trigger points and activation of latent trigger points within the injured muscles. Sustained contraction of muscle to maintain a position (sustained, posture) will also activate trigger points.

During medical and other therapy training programs, we are taught that repetitive strain injury causes inflammation of the overused tissues. This can indeed occur. In the extreme circumstance, there can be physical evidence of an inflammatory condition—called crepitus. Crepitus is the "creaking" that occurs as not-so-well-lubricated tendons fail to glide smoothly. It can sometimes be felt in the swollen and injured tissues. This inflammation can be very serious.