30 seconds each rep, 2-3 reps per leg, 2-3x per day
Lie on the back, supporting the thigh with the hand or with a towel wrapped around it..
Slowly straighten the knee until a stretch is felt in the back of the thigh, trying to get the bottom of the foot to face the ceiling, one leg at a time.
Hold the position initially for 10 seconds, and gradually work up to 20 to 30 seconds.