Some women treat low back pain for years, through physiotherapy, muscle relaxants and new mattresses, and it keeps returning. The structure that often never gets examined is the pelvic floor, which forms part of the trunk support system along with the deep abdominal muscles, the back muscles and the diaphragm.
When one part of that system is not coordinating, the others work harder to compensate. A pelvic floor that is too tight, or that is not moving with the breath, can present as low back pain, hip pain, or pain referring into the thighs. The relationship runs both ways: bracing the trunk and holding the breath to protect a painful back increases pelvic floor tension, which sustains the cycle.
Clues that the pelvic floor is involved include back pain accompanied by urinary leaking, urgency, incomplete emptying, chronic constipation or pain with intercourse; a history of childbirth or perineal tearing; and symptoms that worsen with stress and ease with rest.
Management is often not more squeezing. In many cases it begins with learning to release: breathing so the abdomen expands and the pelvic floor moves with the breath, changing toilet habits so straining stops, and only then rebuilding strength in a deliberate order.
See a doctor if back pain comes with urinary or bowel symptoms, if it has not responded to treatment aimed directly at the back, if intercourse is painful, or if you develop numbness around the perineum or lose control of your bladder or bowels, which requires prompt attention.