Long-distance running for two days knee pain consider joint strain, meniscus injury and other reasons. 1. Joint strain: it may be caused by too much exercise when running or because the muscles are not fully relaxed before running without doing sufficient warm-up, so the amount of activity is too large to cause joint pain, especially flexion and extension of the knee joint or squatting action pain is obvious, this symptom can be alleviated through rest. 2. Meniscus injury: it may be caused by excessive exercise intensity or joint sprain, joint pain is obvious, accompanied by flexion and extension activities sound or stuck, through the knee MRI film can be clearly diagnosed. So two days of long-distance running knee pain if you can reduce through rest is not serious, usually reduce the amount of exercise, if the pain is not reduced, should check the knee MRI film clear.