Ice Packs and the Injury Repair Process

The physiology of a common sprain and how applying ice speeds recovery

“Scratch Thee but with a pin and there remains some scar of it”
As You Like It, 111 5-21

When in doubt as to the severity of an injury, consult a physician.
While awaiting medical attention, consider applying these principles.

The application of ice to an injured or inflamed area is called “cryotherapy.” Our high level of interest in sports activities has prompted much-needed scientific inquiry into how the body heals an injury and the effectiveness of cryotherapy. There is now no doubt that the timely application of ice packs will speed recovery. To understand how and why this therapy works, it’s helpful to know the nature of injured tissues and the ways in which the body responds to repair itself.

Injuries actually occur in two stages. In the initial stage of the trauma when the primary damage is done, the fibers that make up the muscles, tendons, and ligaments are torn. This is what occurs in a typical sprain (torn fibers of a ligament) or strain (torn fibers of a muscle). Cells and nerve endings are damaged and blood vessel walls break allowing blood to leak into cell beds.

Now begins the secondary stage — the inflammatory process wherein further injury can occur. The extent of this secondary injury greatly influences the length of recovery. Many processes are occurring in the moments after your initial trauma. Damaged nerves signal a motor response to surrounding muscles to spasm in an effort to immobilize and protect the injured area. The clotting mechanism begins to seal off torn blood vessels, but leaked blood proteins cause further impairment to the nerves.

Along with the blood proteins, damaged cells secrete particles into the cell bed and cause a change in osmotic pressure. This forces fluid to seep from the undamaged cells into the surrounding tissues. As the cell bed begins to swell with edema (excess fluid build-up), the increased pressure further damages cells and stimulates additional nerve firing resulting in more muscular spasming.

Next, blood flow to the area diminishes allowing white cells to migrate through vessel walls and begin the clean-up process. But the inadequate blood supply and the excess fluid surrounding the cells prevent oxygen from getting into healthy cells. More cells begin to die from hypoxia or oxygen starvation. During this inflammatory stage, if the injury receives improper care, the secondary injury could be greater than the initial one.
A third factor bears consideration: the emotional component of an injury. Fear and worry connected with the original injury grow as the pain increases, adding to the likelihood of muscle spasm. An injured person may experience some degree of shock and have difficulty relaxing and drawing full, deep breaths, increasing the pain-spasm-pain cycle. This downward spiral of nerves signaling pain causes further muscle spasms. Immediate ice application will force the injured person to rest; optimally, to lie down with the injury elevated if possible. This pause provides integration time to restore blood pressure and allow emotional recovery, decreasing secondary injury impact.

Eventually, the debris from the injured area, which consists of dead cells, blood and other particles gather together in a bruise, or hematoma. Over time the white cells, the body’s clean-up crew, begin the process of ingesting the hematoma and carrying it off. Connective tissue fibers that are designed to fill in the damaged areas grow rapidly to mend the wound. This is the formation of scar tissue. The quality of care and the application of ice at the time of the trauma and for the next 24 to 48 hours, are critical to a fast and thorough recovery.

The role of ice in speeding recovery from the injury cannot be over-emphasized. Let’s begin with the initial injury. Immediate ice application will constrict blood vessels, limiting internal bleeding and swelling. By chilling the damaged nerve endings, we can decrease pain signals that cause surrounding muscles to spasm. Chilled cells go into a state of hibernation allowing them to live with less oxygen preventing hypoxic cell death. With the periodic but consistent application of ice, we can limit much of the damage of the secondary inflammatory response. For the first 24 to 48 hours or longer if swelling has not subsided, cryotherapy is the treatment of choice.

During the recovery process that follows, massage may begin along with light exercise of the injured muscles. This is essential to proper healing. Massage and movement help to break up excess scar tissue formation and adhesions and realign the new fibers along lines of stress for maximum strength. Follow up post-trauma massage and movement with — yes, your new best friend — the now familiar ice pack. Ice interrupts the pain-spasm-pain cycle, allowing therapy to begin with less inflammation.

For a more complete understanding of first aid and strategies for the rehabilitation of soft tissue injury, please refer to the article — RICE (Rest, Ice, Compression, and Elevation) and Rehabilitation.