Left leg inner calf pain may be caused by physiological factors such as prolonged poor posture, as well as traumatic injuries to the calf and other pathologic causes including lumbar spine disease, lower limb vascular lesions and local lesions. 1. Physiological factors: mainly due to prolonged fixed posture, strenuous exercise, standing or cold and other physiological factors caused by pain, physiological causes will cause fatigue injury to the inner calf muscles, the accumulation of metabolic products such as lactic acid, leukotrienes, oxygen free radicals, etc., to stimulate the peripheral nerve roots of the calf, the emergence of pain symptoms. 2. Pathological causes (1) Lumbar diseases: Lumbar diseases such as lumbar disc herniation, lumbar spondylolisthesis, and occupational lesions inside and outside the spinal canal may be the result of lumbar disc herniation, lumbar spondylolisthesis, and occupational lesions inside and outside the spinal canal compressing the nerves that innervate the medial nerve of the calf, causing pain in the medial side of the calf. (2) Lower extremity vascular problems: such as venous thrombosis, arterial thrombosis, varicose veins and other lower extremity vascular diseases can cause the symptoms of left leg inner calf pain. (3) Localized lesions: problems in the knee and ankle joints, such as localized myofasciitis, osteoarthritis of the knee joint, or muscle ligament injuries in the inner side of the ankle joint can cause medial calf pain in the left leg. The symptoms of left calf pain alone can not accurately determine the cause, but also need to be combined with the characteristics of the medical history, other test results to make an accurate judgment, it is recommended to clarify the cause of the disease under the guidance of a doctor.