What Causes A Trigger Point?

During a normal muscle contraction, a chemical called Acetylcholine, is released at the junction between the nerve and the muscle.  This chemical sends a message to the muscle, which stimulates the muscle, causing it to contract.

After a normal muscle contraction, the chemical, Acetylcholine , is flushed from the neuromuscular junction and the muscle can then lengthen and relax.

However, when a trigger point exists in a muscle belly, the Acetylcholine does not get flushed from the neuromuscular junction, but rather 'bathes' the muscle in its conductive juices. As a result, the muscle continues to receive a message to contract and remains in a spasm.  If the muscle stays in this contracted state, the muscle becomes shortened and weakened, and is identified as a palpable knot in the muscle belly.