A rest on the side of the knee pain will be reduced when walking, mostly due to chronic strain injury, patellofemoral arthritis, knee cold, and so on. 1. Chronic strain injury: often due to chronic aseptic inflammation of the lateral part of the knee, if you sit and rest for a long time, it will lead to slow local blood circulation, inflammatory metabolites can not be metabolized in time, will cause some stimulation of the peripheral nerves, thus causing leg pain, when walking, blood circulation is accelerated, inflammatory metabolites can be metabolized, pain relief. 2. Patellofemoral arthritis: when suffering from patellofemoral arthritis, due to the patellofemoral joint part of the pressure is relatively large, which leads to pain around the knee joint, and when walking, the pressure is reduced, and the pain will also be reduced. 3. Cold knee: It may be due to muscle spasm caused by cold in the lateral part of the knee, after walking, because the blood circulation in the leg is accelerated, the symptoms of cold are alleviated, and the pain is alleviated. Once resting the side of the knee pain will be reduced when walking, there may be other causes, if the symptoms recur, it is recommended to consult a doctor in a timely manner to identify the cause of targeted treatment.