HOW: Sit in a chair, ideally a taller one so your feet are off the floor. Tie a theraband or other resistance band around one end of the chair and place your ankle through it. Squeeze your top thigh muscles as hard as you can and try to straighten your knee.
FEEL: You should feel all the muscles in the front of your thigh working. It will feel harder the higher you lift your foot.
COMPENSATION: If the band is slipping, pull the band away from your ankle and cross the bands to form a loop. Put your toes through the loop to secure the band to your ankle.