The butt or shall I say the gluteals. A woman comes into the office with back pain. She bends over from her waist to get her insurance cards out of her purse which she has placed on the floor. Hmmm....that kind of bending done a lot will cause fatigue and eventually back pain.
On observation, the woman's buttocks is very flat -she does not seem to have much bulk to the gluteal muscles that make up the buttocks. She is likely bending the way she is-from her waist-because she does not have a great deal of strength.