Contrast therapy, which consists of alternating applications of heat and cold, is also used to treat athletic injuries. The most common approach to contrast treatment consists of alternately immersing the foot, ankle, and leg in a cold water whirlpool or bath and a warm whirlpool (figure 8.13). The temperature of the cold bath and warm whirlpool should be within the ranges previously described in this chapter. The literature provides several recommendations (Walsh 1996; Bell and Prentice 1998) about the length of time cold and heat should be applied, as well as the number of cycles of heat and cold that should be completed during a treatment. A cold-to-warm ratio of 1 to 3 min or 1 to 4 min appears reasonable based upon clinical observations and experience.
Several physiological effects have been proposed to explain the benefits of contrast therapy. Many have suggested that contrast therapy results in cycles of vasodilation and vasoconstriction, thus creating a pumping action to reduce swelling. However, tissue temperatures are not affected by contrast treatments (Myrer et al. 1994, 1997; Higgins and Kaminski 1998). The brief exposure to cold and the fact that superficial heating has minimal effect on deep blood flow suggest that there is little vascular response to contrast therapy.
Even though there is no good explanation for the effects of contrast therapy, this approach has been used to treat some physically active individuals. For example, contrast therapy may be effective in reducing edema in subacute foot and ankle injuries. When swelling limits range of motion several days after injury, contrast therapy along with active range of motion appears to reduce swelling. The sharp sensory contrast between heat and cold appears to reduce pain and therefore muscle spasm. Models of descending influence over dorsal horn processing of nociceptive input certainly offer a plausible explanation for the analgesic response to contrast. A decrease in pain and spasm, combined with active, pain-free range of motion, would in turn increase lymphatic drainage from the area and decrease swelling.
As with many therapies, there has been little investigation of the effectiveness of contrast treatments. Cote et al. (1988) reported that swelling increased in sprained ankles after contrast therapy administered over 3 days after acute lateral ankle sprain. Certainly, these results suggest that contrast therapy should not be administered early in the plan of care. Kuligowski et al. (1998), however, found that contrast or cold therapy had more effect on pain and loss of motion associated with delayed onset muscle soreness than superficial heat. Further investigation is needed on this treatment approach to identify if and when it should be applied.
Pain and muscle spasm indicate the use of cryotherapy, superficial heat, and contrast treatment. This raises the question, which is best? There is no simple answer, and you must consider several factors when selecting a modality, weighing the potential benefits against potential risks.
Contraindications are the first consideration in selecting a therapeutic modality. If the injured person suffers from Raynaud’s phenomenon (cryoglobinemia, hemoglobinuria) or cold urticaria, then cold and contrast cannot be used.
Traditionally heat has been thought to be contraindicated after acute injury because of the associated increase in blood flow. Although superficial heat has little effect on deep muscle temperature and blood flow, many clinicians recall cases where an injudicious application of heat increased pain and swelling after injury to joint structures. Thus, cold is the treatment of choice in the management of acute injuries because it is an effective analgesic and antispasmotic and may minimize secondary tissue injury. In the management of acute injuries, cold should be combined with protection of the healing tissues, compression, and elevation. Thus, cold pack application is preferred over cold water immersion or cold whirlpool, because these treatments place the limb in a gravity-dependent position.
If neither heat nor cold is contraindicated and the condition is not acute, you must consider other factors in choosing between cryotherapy, superficial heat, and contrast therapy. The most important considerations are the severity of pain and muscle spasm and patient preference. Cold is a better choice when pain and muscle spasm are severe. However, the preference of the individual is also important. If a certain treatment has helped a person in the past, he or she is likely to believe that the treatment will work again and is likely to actively participate in a plan of care that includes the specific treatment.
Compliance by the injured individual is especially important in a sports medicine clinic. The certified athletic trainer often must develop home treatment programs for athletes who are treated in the clinic only once or twice per week. Certainly someone who prefers not to be treated with cryotherapy is unlikely to use cold at home unless provided with a very convincing argument about why such treatments are essential to his or her recovery. Thus, the ease of application and the probability of compliance with home use are also considerations when you are choosing between cryotherapy and superficial heat.