The Hip Extension
Possibly the second most reviled machine in the studio is the Hip Extension (#1-Leg Press). Without question, it is the hardest machine to teach and the hardest to learn proper form.
The belt is the reason the Hip Extension is not an eagerly anticipated part of the workout. The belt, when properly placed, should cross the hips just below the iliac crest. It prevents the machine from throwing you out of alignment during the eccentric portion of the movement and it helps keep you stable during the concentric portion of the exercise. The belt is a little snug, especially at the top of the range-of-motion, which can cause a little discomfort. The trick to minimizing that feeling is to anteriorly roll your pelvis (i.e. push your tailbone down to the floor) which will allow you to focus more on the involved musculature, take your lower back muscles out of the picture, and relieve the abdominal pressure caused by the belt.
The primary muscles used in the Hip Extension machine are the Gluteus Maximus and the Hamstrings. At the beginning of the exercise, your thighs should be approximately perpendicular to the floor and your shins should be parallel to the floor. The movement should be initiated by the glutes. Think about pulling your leg around the hip joint. The next thought should be to extend the heels across the room (not up to the ceiling). This will allow your hamstring to help conclude the movement. A slow reversal of the movement arm will bring you back to the top to start another repetition.
This exercise is truly a pain in the butt!