Seen it happen to a few buddies when playing football. Usually only happens (my experience) with guys who are way over weight. One thing I remember the trainers always doing was have the guys stretch their legs and then feet but then they would put towels down on the floor and have then pull in the towel with their toes. Once they got to doing that easily they would add 2.5lb weights and then up to 10lb weights.
Call the Athletic Trainers at one of your local colleges and ask their advice on it as well. If they can't help then ask for someone they can refer you to. Usually they can help put you in touch with someone who can help you.
