When you have leg cramps, especially calf cramps, it is easy to feel the muscles of your calves tangled hard as rocks, but in fact this is just the muscles in your legs cramping (muscle cramp). What exactly causes muscle cramp in the legs? 1, calcium ions to maintain the normal level of muscle excitement, calcium deficiency is, the muscle will become restless up, a little slight stimulation will occur cramps. 2, and fatigue is the common cause of the collection of metabolic waste. Muscles work for a long time not only consume a lot of energy reserves of glycogen in the muscles, but also produce a lot of creatine, lactic acid and other metabolic products, just like workers who work in a row for a long time, accumulating a lot of dissatisfaction, and once there is a fuse, they go on strike through the form of cramps. 3, cold and fatigue tend to trigger leg cramps, which is reflected in swimming. Our body after a long swim, leg muscle fatigue, resulting in the collection of metabolites inside and outside the muscle cells, plus the stimulation of cold water, the brain frequently launch muscle contraction to produce heat, muscle overwhelmed, so to spasm to protest. So, if you are crazy about shopping during the day and unfortunately let your calves out of the coverage of the quilt at night, it is not so surprising to be woken up in the middle of the night by cramped calf muscles. Of course the above are simple cramps that can be relieved quickly with the right treatment, or even without treatment, after rest