What is a Trigger Point (TrP)

Trigger points, also known as myofascial trigger points (MTrP), can be thought of as tension or cramps in the muscles. These tensions usually arise due to chronic overload, traumatic overstretching, or prolonged static load and originate at the smallest functional muscle level, the sarcomere.

To this day, it is challenging to obtain precise insights into the structural anomalies of trigger points because there are no suitable imaging methods available. Current knowledge emerges from consistent results in electrodiagnosis and histopathology.

At the center is the concept of an energy crisis. This concept assumes an increase in calcium due to an injury in the muscle. The increase in calcium concentration leads to permanent contraction of the sarcomere, thus increasing metabolism while simultaneously causing a lack of oxygen. This leads to an energy crisis in the muscle, and the excess calcium cannot be reabsorbed.

This means that over prolonged periods, parts of the muscles are undersupplied with oxygen and remain in constant tension – the muscle fibers can no longer relax and contract. MTrP's arise with an associated taut band that disrupts the overall function of the muscle.

There is a distinction between latent and active trigger points. Active TrP leads to distinct clinical complaints, which the patient recognizes when they are irritated by pressure or traction. These complaints are not limited to the affected muscle and the muscles that support or inhibit its action but affect the entire functional unit, including the joints over which the muscles exert their force.

Latent trigger points often go unnoticed but can still lead to significant motor function restrictions in the muscles. These functional limitations can lead to mechanical misuse of the muscle (overload), turning a latent TrP into an active one.

Further findings indicate that the area previously referred to as a trigger point is actually an accumulation of numerous, microscopically small points that cause the known pain. The TrP resembles an ant nest, storing numerous wrongdoers.

The physiotherapist uses various techniques to resolve MTrP, including manual trigger point therapy and dry needling.