Hold on to something for balance. Standing on one leg, grasp the foot of the other leg. Keep your knee pointing down. Pull up with light pressure. You do NOT need to pull up all the way to your buttocks. If it feels uncomfortable or painful, you are putting too much strain on the knee joint.
Hold your foot behind you for 10-20 seconds, then switch sides. You should feel the stretch in the front of the thigh.
Update Date 8/17/2014
Updated by: Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.