Occasional leg shaking is generally not harmful, but if you shake your legs frequently, it may cause some damage to your knee joints. Shaking legs belongs to a bad habit, just occasionally shaking legs will not have any harm, and frequent shaking legs will make the legs constantly vibration, due to rapid knee flexion and extension may accelerate the knee joint strain and degeneration, if there is a bad habit of shaking legs, be sure to timely and actively correct. Some people in the leg shaking, posture may also be cocked legs shaking legs, in the long run may even be on the hip joints and lumbar vertebrae caused by a certain impact, but also increase the pressure of the other leg, may also induce varicose veins of the lower extremities in severe cases.