Pain in the medial knee after swimming, mainly consider the following aspects: 1, medial knee bursitis, is due to knee flexion and extension activities are too frequent, back and forth friction leads to aseptic inflammation between the surrounding tendons and soft tissues, and the formation of fluid, manifested as bursitis, clinical symptoms are mainly pain when walking, can be relieved when resting, local can feel the mass, ultrasound examination can be clear. 2, cold or strain In the case of arthritis, it is better to rest and reduce activities.