I have recently gotten serious pains in my knees and my foot. I think the reason for this is because I play ALOT of basketball outside on the concrete and recently I have been trying to dunk with 2 hands. I think that all that hard jumping has taken a toll on my knees and feet. How do I prevent this from happening without having to stop going to the park? The pain is pretty bad too like I have to be cautious the way I walk because my knee hurts every time I step, especially up the stairs.