What is a Trigger Point? Part 1

What is a trigger point?

If you have ever gotten a massage therapy treatment  by a RMT, I am sure you have heard the word trigger point.  It is one of the most common cause of myofascial pain, and is treated with all different types of manual therapies.

A trigger point is often described as a painful nodule found in a taut band of muscle.  Trigger points can often refer pain elsewhere, limit range of motion, cause painful movement, and make a muscle weaker.  The question is… what causes these trigger points?!

 

To be honest, the actual cause of trigger points are still in debate, but I will cover the most commonly accepted causes of myofascial trigger point development.

Trigger points, its all electrical and chemical

It all starts with electrical impulses and chemicals reactions.  A muscle contracts when it receives a message from a nerve, via electrical impulses.  This neurological transmission starts in the brain, and makes it way down a nerve until it reaches a receptor called the motor end plate.  when stimulated, by the neurological impulse, the motor end plate releases a chemical called acetylcholine.  This chemical travels to the muscle cell, and causes the cell to release calcium.  Calcium causes the muscle fibers to contract. In a normally functioning neuromuscular unit, when the muscle contraction is no longer needed, the motor end plate stops releasing acetylcholine, and the muscle cell reabsorbs the calcium, which causes the muscle to relax it’s contraction.

neuromuscular-junction.jpg

 

If trauma occurs, like overloading of the muscle,( Ill talk about this later)or there is an significant increase in acetylcholine released by the motor end plate there will be an excessive amount of calcium released by the muscles cell.  This will cause a very strong contraction in the muscle fibers that are affected.  This strong contraction causes a decrease in circulation getting to the affected tissues.  If there is a lack of circulation getting to the contracted muscle fibers, the muscle cells do not get enough oxygen and nutrients that are necessary for them to reabsorb the calcium. The result is muscle fibers that are chronically stuck in contraction, with a decrease in healthy circulation. This is what causes the taut band in the affected muscle, and the hyper irritable spot, aka trigger point, is the location of the dysfunction.  Because this dysfunction causes a cycle of muscle contraction, leading to decrease circulation, leading to more muscle contraction, the trigger point, and pain will not go away on its own.  Intervention, such as massage therapy and stretching is needed to break the cycle by increasing circulation and releasing adherences between muscle fibers.

 

Part 2 of  “What is a trigger point?”, coming next week,  will cover causes of muscular overload that can lead to the development of a trigger point.

See you next week