Calf pain, may involve a variety of reasons, common are as follows: 1, the calf suffered acute injury, such as strenuous exercise caused by strains, contusions, or direct violence hit injuries and fall injuries, etc., will lead to the calf due to acute injuries, local hemorrhage, hematoma compression, inflammation reaction, resulting in pain. 2, can be seen in the calf chronic strain injury, such as long time high load labor, long standing, long walk, and athletes long time training, there will be a chronic cumulative injury to the calf, resulting in local aseptic inflammation, resulting in pain 3, can be seen in the calf of the blood circulation is unfavorable, such as varicose veins, vascular disease, vasculitis and so on, will appear due to blood stagnation, resulting in pain. 4, the calf nerve problems, such as peripheral neuritis, and the lower extremity sciatic nerve trunk is compressed, such as the pear-shaped muscle outlet syndrome. 5. Sudden pain in the back of the calf at night or during sleep is often a sign of low calcium or osteoporosis. For middle-aged women, such as before going to bed will also appear in the body of the precursor of calcium deficiency, so after the frequent occurrence of symptoms, you should promptly go to the hospital for bone mineral density or electrolyte calcium and phosphorus examination, to see whether it is in the pre-calcium deficiency or calcium deficiency period.