Our study was designed to test the hypothesis that the painful coccyx syndrome is capable of affecting the overall activity as well as the latency of onset of this activity in the m. gluteus maximus in the stereotype of hip extension. Using PEMG, we examined the stereotype of hip extension in a group of 23 patients with the typical picture of painful coccyx before and after its treatment. We demonstrated that, in 17 patients, treatment of painful coccyx by isometric relaxation of the lower portion of the m. gluteus maximus and pelvic floor muscles resulted in immediate improvement of the activity in the above movement pattern.

        Key words: coccygodynia, gluteus maximus muscle, ischiocrural muscles, low back pain, coccyx, polyelectromyography