Cold water immersion is a common technique that some athletes use as a part of their recovery routine after intense physical exercise. The cold water is said to improve recovery speed and reduce muscle pain and soreness after exercise. These methods are widely used but lack in scientific supportive evidence.
During intense exercise, such as training, competition, or rugby and other games, tiny tears occur in the muscle fibers, called microtrauma. Even though the muscle tissues are damaged, this actually helps new muscle cells to grow and promotes overall muscle growth. The damage does come at a price, however, in the form of delayed onset muscle pain and soreness, usually occurring within 72 hours of intense exercise. Cold water immersion is said to help relieve the symptoms of muscle pain and soreness.
A lot of the pain associated with muscle microtrauma is caused by an over-production of lactic acid. Cold water immersion is believed to constrict blood vessels and flush out waste, such as lactic acid. It is also thought to help with pain by slowing down metabolic activity and all other physical processes, such as swelling and further irritation of the muscle tissue.
A typical cold water immersion session is done shortly after exercise. The exact routine varies from athlete to athlete, but most people recommend a temperature of about 54 to 59 degrees Fahrenheit (12 to 15 degrees Celsius). Immersion times range from five to 10 minutes, and some people will even soak in these cold temperatures for up to 20 minutes. Many trainers and athletes also recommend alternating between cold and warm baths for best results.
Whether or not a warm bath follows the immersion, the natural rewarming of the body is a key part of the recovery process. The blood vessels will relax and expand, increasing blood circulation. The increased blood circulation is believed to further speed along the recovery process and help flush out more waste products. Many athletes and trainers swear by these techniques, but the actual science is lacking in supportive evidence of its effectiveness.
A study conducted by the International Journal of Sports Medicine in July of 2008 found that cold water immersion and alternation between cold and warm water baths may improve recovery times when compared with hot water immersion and complete rest. Another study from the British Journal of Sports Medicine in 2007, on the other hand, found that cold water baths had no real benefit and may actually increase muscle pain. A separate study in 2007 by the Journal of Strength and Conditioning Research found that alternating between cold and hot water immersion speeds up recovery times for athletes. These studies offer inconclusive evidence because there are too many variables involved in the types of exercise, temperature of the water, and immersion times.