Exercises for the PF Joint
First warm up- run, bike, run in place, elliptical machine, ergometer-whatever it takes to raise heart rate to a cardio conditioning level that is appropriate for you. For most healthy young people, this is double your normal heart rate.
Avoid any exercise that increases pain.
Then work on toe touching (yoga is great for this) for 2-3 minutes,
Followed by quad stretching (lie on your stomach, grab one ankle at a time and gently pull ankle to fully flex knee, progressively increasing the stretch over one minute. Then switch to the other side and do each side 3 times
Next work on the lateral knee. One way is to lie on a bed on your side, flex the down side leg to your chest, and then drop the upper leg, fully extended, off the side of the bed until you feel the lateral stretch. Hold for 30-45 seconds, repeat 3 times and then switch to the other side.
Now focus on hip and lower body balance. One great way to do this is to jump rope with your knees pointing straight forward, like the headlights of a car.
Finish up by working on your core, trunk stability. Sit ups or ab curls, followed by lying on your stomach and arching with hands and feet off the ground works well. Spend about 2 minutes on each, then repeat.