There are multiple known benefits to cryotherapy including:
Diminishes the inflammatory reaction to trauma.
Reduces Edema
Minimizes Hemmorhage
Produces analgesia through altered nerve conduction. This is likely due to diminished amplitude of nerve action potentials, or, if sufficient cooling takes place, to actual blockage of nerve conduction. The analgesic effect is maximal immediately after icing and declines over a 30 minute period.
Local vasoconstriction leading to decreased blood flow to the injured area.
Reduces muscle spasm
NOTE: Cryotherapy is much more effective when uses with compression.