A trigger point is a spot on your muscle that feels like a taut band or some might say ‘knot.’ They can cause pain when I touch them, or you might just feel spots of dull pain every now and then with no known reason as to why.
These happen due to problems with muscle cells metabolising and producing energy and nerves communicating with each other. It can be like the chicken or the egg analogy, where the muscle cell wasn’t processing things properly and producing the right information for your nerves therefore creating a problem or the nerve was having trouble either receiving or sending off a signal to the muscle that is creating the problem. These points are often pre-set and common in certain places on the body.
It is still a mystery as to why they are preset or common in certain areas….. however, a lot of them lie over mechanical points of strain or junctions in muscle, so a theory could be they are areas commonly stressed in what could be seen as common or general human movement patterns.
As with any mystery, there is always science out there, breaking it down to its smallest parts, deciphering and theorizing ways to solve this chicken or egg problem.
For those into that deeper scientific juicy stuff! Read on:
A trigger point is a taut band and pre-set point on a muscle.
Trigger points can be active or latent.
Latent trigger points only produce pain when you palpate them.
Active ones are present pain regardless of touch.
Trigger points are spots in muscle fibres (that house in descending order myofilaments, myofibrils, to myosin and actin filaments) where myosin and actin filaments do not bind and slide as affectively and frequently due to cell dysfunctions causing neuron stimulation to be too low to create an action potential to cross the neuromuscular junction.
The reason musculoskeletal cells and peripheral and central nervous system neurons don’t potentiate action potentials properly can be numerous and it is up to yourself as a practitioner to use your diagnostic sieves to filter through all the systems that could be affecting this dysfunction and formulate a differential diagnosis.
Active trigger points also have central sensitisation present.
Some current theories for trigger point formation on a cellular level include the Energy Crisis Theory and the Motor End Plate Theory.
Energy Crisis Theory
The energy crisis theory dictates a trauma or tear occurs in the sarcoplasmic reticulum found in muscles cells. This causes it to leak calcium ions, which in turn causes the muscle to stay bound or contracted as there is now too much calcium present for achetylcholine to allow the myosin to un-bind with the actin and lengthen. This results in muscle spasm, shortening or cramping, which in turn, results in less blood flow and a failure to remove metabolites and waste.
Summary of what happens in the Energy Crisis Theory
Motor End Plate Theory
Dictates the tear in the sarcoplasmic reticulum and central sensitisation are responsible for trigger points when combined with spontaneous electrical activity.
Main take away: A sensitive locus caused by what is described in the energy crisis theory AND a site of sponetaneous electrical activity is responsible for a MTrP (Muscular Trigger Point).
So now you know a little bit more about what trigger points are and what your therapists magic hands are doing.
If you’d like to know more about how trigger points are treated, read ‘What does Dry Needling do?’
Wishing all health, wellness & success
Jess Jelleff
BhSc. Clinical Myotherapy
Owner/Operator of Affinity
Image Sources in Order of Appearance:
https://upload.wikimedia.org/wikipedia/commons/f/f2/Trigger_Point_Complex.jpg
