Within those muscle fibers or the fascia covering them, constrictions can occur that restrict blood circulation to the area, causing small but sometimes very painful contractions of portions of the muscle or fascia.

These constrictions can be caused by trauma to the muscle from an injury or surgery, dehydration, over-exertion or even bad posture (for example, hours hunched over a computer keyboard).

The poor circulation prevents the affected tissue from receiving necessary oxygen and causes a buildup of toxins and other waste materials in the cells. 

It is common for multiple trigger points to develop in the same zone. Once one trigger point begins to have involuntary contractions, other portions of muscle and fascia are also likely to be affected. 

If the constrictions are severe, it may require several treatments to work them out. Remember, that “knot” in your muscle probably developed over time, and may not completely disappear all at once either. But you definitely should feel significant relief from the first treatment.