Originally Posted by HIPCHIP

Knees have so many different structures that it can be anything. Do some careful stretching of the knee area, and ice it for 20 minutes on, and at least 40 minutes off after activity. This will help reduce any inflammation. If it keeps causing problems, get it checked by a good sports orthopedist. It sounds like it was just a mild strain of the quads at the insertion, but it could be a meniscus problem, or cartilage behind the kneecap or anything else. All can go from being a minor problem to something that sidelines you for some time, so get things checked if you can.