With vaginismus, the mind and body have developed a conditioned response against penetration (see causes). The body has learned to expect or anticipate pain upon penetration, so that the powerful PC muscle 'flinches' or contracts to protect against the potential of intercourse pain. This can be equated to automatically blinking one's eyes and wincing when an object is hurled toward us. It is not something a woman thinks about doing- it just happens.
The tightened PC muscles may cause burning or pain with sex or may completely block entry. Instead of preventing pain, the tightening of the PC muscle group ultimately causes pain; although acting as a defense mechanism against pain, the opposite effect results.
Vaginismus has a wide range of manifestations, from impossible penetration, to intercourse with discomfort, pain or burning, all resulting from involuntary pelvic tightness. When a woman has never been able to have pain-free sexual intercourse due to penetration difficulties, it is generally classified as primary vaginismus. When a woman develops the vaginismus condition after having previously enjoyed problem-free sex, it is generally classified as secondary vaginismus. Depending upon the classification, there may be some minor differences in the way in which vaginismus is treated (see diagnosis).