Many people may have calf cramps in winter, there are many reasons, mostly seen in calcium deficiency, there is a decline in calcium in the bones or osteoporosis patients appear cramps. There is also a part of muscle cramps, when the day is cold, the night warmth is not done well, there will be this kind of cramps, so it is necessary to analyze what kind of cause is caused, if the bone density decreases, already have osteoporosis, to supplement calcium and vitamin D as early as possible, will relieve muscle cramps. If the muscle spasm is due to cold weather or vascular factors, it may be very helpful to keep warm, especially when the weather gets colder, to keep warm relatively early and notice the change in temperature or muscle changes. If there are other causes of tonicity and spasm, such as some other lesions of nerves and muscles, it may be necessary to do electromyography or go to neurology to further investigate the causes, including sciatic nerve problems, to further clarify other causes.