Have you ever heard of cryotherapy? Sounds like having a good cry to feel better. Actually, cryotherapy, or cold therapy, refers to cooling body tissue to relieve pain and swelling. Using cold as a form of therapy started back in ancient Greece. Today, we know that cold also changes how fast the nerves send messages. It lowers the metabolic rate and blood flow in the treated area, and it relaxes the muscles.
There are many ways to apply cold to an injury. Some people use a simple cold pack. Others apply ice directly to the area in a circular motion called “ice massage”. Athletic trainers and physical therapists may recommend an “ice bath.” This refers to placing part of the body such as the hand or foot into a bucket of cold, icy water.
Sound too cool to be true? We know how cold affects the skin. But what about the joints, muscles, tendons, and ligaments? How deep does cold go? And how long does it last? Inquisitive physical therapists conducted an experiment to find out.
A cold pack was applied to the thigh muscle (quadriceps) for 20 minutes. Temperature was measured at various depths before, during, and after cold therapy. Within the first eight minutes, the skin and top layer of muscle tissue (about a quarter-inch) were cooled. This area remained cold throughout the rest of the treatment. During that time, the temperature of the deeper tissues remained unchanged.
Once the cold pack was removed, the skin and top layer returned to normal in less than an hour. At the same time, the temperature in the deeper tissues (down a half-inch) actually went down. This happened when blood in the deeper tissues moved up to rewarm the cold tissues above. Blood vessels in the skin and first layer of tissue also widened when the ice was removed. This brought more blood to the area and helped warm it up.
Cold can be used to decrease pain, muscle spasms, and swelling. It causes a direct decrease in skin temperature and an indirect decrease in the temperature of deeper tissues. This is important information for physical therapists in deciding what kind of cold therapy to use for different kinds of injuries.