In clinical practice, a response can often be encountered, when managing a painful coccyx, not only in muscles in the pelvic region but, also, in paraspinal erectors of the torso. Our study was designed to test the hypothesis that spasm of the m. gluteus maximus and muscles of the pelvic floor are factors capable of modulating the pattern of hip extension. Using PEMG before and after post-iso- metric relaxation of the above muscles, we examined the stereotype of hip extension in a group of 24 patients with the typical picture of painful coccyx. We have shown that, in 22 out of the 24 patients, treatment of painful coccyx using PIR resulted to an immediate change of the movement pattern.

        Key words: coccygodynia, hip extension pattern, low back pain, coocyx, polyelectromyo- graphy