Waking up in the morning with sore and weak calves may be caused by overwork, or it may be caused by hypokalemia, lumbar spondylosis and other diseases. 1. Overwork: If there is a lot of labor or strenuous exercise on the previous day, lactic acid accumulates in large quantities, which may cause calf weakness, and waking up in the morning after a night’s rest will result in calf soreness and weakness, and the symptoms can be gradually relieved after sufficient rest. 2. Hypokalemia: In the early stage of hypokalemia, patients may experience weakness of limbs in addition to soreness and weakness of calves, and with the development of the disease, muscle weakness of the whole body may occur. 3. Lumbar spondylosis: when the protruding intervertebral discs and hyperplastic bone compress the local nerve roots, it may radically lead to weakness and tenderness of the lower limbs. In addition to the above, diseases such as spondylitis and Guillain-Barre Syndrome may also cause aching and weakness of the legs. It is recommended to go to the hospital as soon as possible to find out the cause of the disease and standardize the treatment under the guidance of the doctor.