Trigger points are sore spots that occur in a muscle; they’re big enough to feel, and most people know them as muscle knots. Trigger points may be active or latent.
Muscle pain is the result of active trigger points. Latent trigger points lie dormant in the muscle, only to cause pain at some future point when stress, tension or movement releases them. Practitioners of trigger point therapy believe that latent trigger points are behind the joint stiffness and limited range of movement that accompanies old age.