This condition is the culprit behind most lower back problems, where herniated disks and sciatica most often occur. The hip flexors, spinal erectors, TFL, piriformis, and QLs are tight and overdeveloped, while the gluteus maximus, gluteus medius, and abdominal muscles are weak. (The hamstrings and adductors are also usually tight.) In this syndrome, the abdomen may protrude, the lower back arches, and one or both feet turn out. This posture places a great amount of stress on the disks in the lower back. As the abs get relatively weak, the QLs and hip flexors tighten and further stress the lower portion of the spine—until a simple twist or forward bend “pulls your back out”!
—Perfect Posture, 16