How to: Place both feet flat on the floor knees bent, draw-in your navel & extend through your hips by driving through your glutes until knee, hip & shoulders are aligned. Then extend 1 leg straight out keeping the thighs in-line with each other by stabilizing the pelvic. Hold for 2-3 sec then alternate sides for prescribed sets & reps.
Compensations: Watch for dropping of the hips, even the slightest. The goals is to show no movement. Watch for elevation of the shoulders to help brace.