Decrease metabolic rate
Cryotherapy can be used for sports injuries such as an injured muscle. As a result it lowers of the temperature of the injured tissue and helps the tissue survive the period of the following injury due to the reduced metabolic rate. Hence, cryotherapy decreases the metabolic rate.
In other words, the rate of chemical reactions can be influenced by factors such as temperature. Therefore if there's a drop in temperature, the rate of metabolism will also drop.
By reducing the cells metabolic rate, ice reduces the cells oxygen requirements. Thus when blood flow has been limited by vasoconstriction then the risk of cell death due to oxygen demands, called secondary cell necrosis will be decreased.