There are 2 basic types of trigger points: active and latent. Active trigger points cause muscular pain and will refer pain and tenderness to another area of the body when pressure is applied. Latent trigger points only exhibit pain when compressed, they do not refer pain to other areas of the body and are one of the causes of stiff joints and restricted range of motion in old age. The pain caused by trigger points may be the biggest cause of disability and loss of time.
Attribution: Straight Talk Foundation