What is a trigger point?
Muscles are made of up of fibres, called sarcomeres, that overlap each other. When the sarcomeres contract, they attach to the adjacent fibres and pull, resulting in movement of the muscle. To release this movement the sarcomeres let go of their hold on the adjacent fibres and the contraction stops.
A knot, or more accurately a trigger point, is formed when the sarcomeres are constantly firing, or 'switched on'. It can feel like a nodule or knot in the muscle when felt through the skin and can refer pain beyond the knot itself.