Calf weakness is mainly caused by physiological reasons, arterial disease, venous disease, lumbar spine disease, cervical and thoracic spine disease and brain disease. 1. Physiological reasons: Excessive exercise, such as prolonged high-intensity exercise, or exercise intensity significantly more than the body’s tolerance, the calf muscles will be fatigued and weak, you will feel sore and weak. 2. Arterial diseases: arterial diseases of the lower limbs such as arterial stenosis, arterial occlusion can lead to poor blood and oxygen supply to the calf, causing calf pain and weakness. 3. Venous diseases: venous lesions in the lower limbs such as varicose veins and other diseases lead to poor venous blood return, and the blood in the lower limbs will be stagnant in the lower limbs, leading to soreness and weakness of the calves. 4. Lumbar spine diseases: Lumbar spine diseases such as lumbar spinal stenosis and lumbar spondylolisthesis because of the compression of spinal nerves, spinal nerves innervated by the muscles of the lower limbs can appear soreness and weakness of the lower limbs. 5. Cervical and thoracic spine diseases: lesions in the cervical and thoracic spine lead to abnormalities in the spinal cord, which can also lead to lower limb weakness and tenderness. 6. Brain diseases: lesions of the brain and brainstem can also lead to lower limb tenderness and weakness because of the involvement of the nerves that innervate limb movement. The appearance of calf muscle soreness and weakness need to go to the hospital in time, do not delay and miss the time of treatment.