Soreness and weakness of the left foot are common in the following cases: 1. Most commonly, after prolonged walking or overwork, muscle strain and inflammation of the fascia in the lower extremities, which generally causes soreness, swelling and muscle weakness, which can be relieved after rest. 2. 4.Cranial lesions, cerebral infarction, cerebral hemorrhage, resulting in weakness and difficulty walking in the lower extremities, mostly combined with weakness in the upper extremities and central neurological symptoms such as distorted mouth and eyes. 5.Vascular lesions in the lower extremities, such as deep vein thrombosis and arterial embolism, resulting in weakness due to local blood flow failure.