The fourth and most important stage is numbness. As soon as this stage is achieved, remove the ice. Time duration depends upon body weight. Twenty to thirty minutes should be the maximum time per area. If it is necessary to reapply ice, let the skin go to normal temperature or go back to the third stage of aching.
Ice initially constricts local blood vessels and decreases tissue temperature.
This constriction decreases blood flow and cell metabolism, which can limit hemorrhage and cell death in an acute traumatic injury. Ice therapy can help the area heal faster, and there will be a decrease in pain and swelling and an increase in lymphatic drainage. In the past 28 years, there have been many studies of ice as a therapy tool for injuries. Many of these studies have had conflicting conclusions, but improvements in technology are giving researchers new data. There is no doubt in the minds of many researchers and doctors that ice is the most widely used and efficient form of cryotherapy in medicine today.