Gluteal Sets
Notice in this image the "forward tilt" of the pant line.  This is INCORRECT.  It occurs with both tight hip flexors and weak abdominals.
This image shows the CORRECT positioning of the pelvis.  Notice that the pant line is straight.  To practice this, contract your gluteal (or butt) muscles.  Do NOT contract your stomach muscles at the same time!
Links:
Piedmont Physical Medicine and Rehabilitation

We Help What Hurts

Exercise Pictures Home

Sacroiliac Exercise

Abdominal/Back Exercise

Back/Legs Exercise 1

Back/Legs Exercise 2

Hip and Knee Exercise

Knee Exercise

Neck Exercise

Shoulders Exercise

OA Exercise

Scapulo-Thoracic