Cryotherapy, or cold therapy, is a common modality used in the treatment of soft tissue injuries. Cold therapy has an impact on a tissue’s metabolism, pain response, and hemodynamics, thus aiding in the management of the inflammatory response.  

Cryotherapy reduces tissue temperature, which slows the rate of chemical reactions, thereby decreasing the demand for energy . This is an important concept because an injured cell uses glycolysis for its energy production. This metabolism puts a high demand on the cell and leads to hypoxia and, eventually, to cell death.

By lowering the metabolic/energy demand with cryotherapy, this allows more cells to survive the period of anaerobic energy production .  In addition, when a tissue is injured, specific nerve fibers become activated and begin sending input to the spinal cord.

The faster the conduction of this input, the higher the perception of pain and the greater the possibility for muscle spasm. When cryotherapy is applied, the velocity of the fibers is decreased, an analgesic effect is produced and muscle spasm is reduced . 

When tissue temperature is decreased 1C there is a decrease of 1.2 m per second in motor nerve conduction velocity and subsequently a 2 m-per-second drop in sensory nerve conduction velocity. 

It has also been demonstrated that the application of cryotherapy decreases blood flow to the injured region, thus reducing edema formation . The combined effects of decreased energy requirements, reduced blood flow, analgesic response, and swelling reduction all diminish the tissue’s inflammatory response, ultimately resulting in a shortened healing process and hastened return to activity.