Heat and Cold Therapy

 

Heat and COLD Therapy

This discussion, and the next, will focus on the use of therapeutic heat and cold. There is certainly abundant confusion and controversy regarding the indications for and use of these modalities. Hopefully, after these reviews, you will have a better idea about when and where to apply heat and cold treatment to running injuries. Cryotherapy is defined as the use of cold temperature as a form of treatment for an injury. Although cryotherapy dates back to the ancient Greeks (Hippocrates), it is only recently (1940’s) that cold has been used extensively for the treatment of acute and subacute injuries, and rehabilitation.

As we shall see with heat therapy, temperature alterations have four main effects on surface body tissues, including pain relief (analgesia), muscle relaxation, blood vessel alterations, and connective tissue effects. By reducing the speed of impulses conducted by nerve fibers, pain sensations are inhibited by cold. Target temperatures of 10-15 degrees C are recommended. Similarly, decreases in muscle spasm are seen with cold therapy, although the exact mechanisms for this are unclear. It is thought that this result may be mediated through reflex reduction in motor nerve activity secondary to response to increased activity in cold receptors.

With regard to the circulatory system, cold causes constriction of small arteries and veins, by direct stimulation of the smooth muscle lining these vessels. However, a curious reverse relaxing effect occurs with very low temperatures or prolonged cooling. The benefits of vasoconstriction include decreased hemorrhage and swelling within injured tissues, although some animal studies have shown a paradoxical increase in swelling with cold application.

The usual therapeutic techniques include direct application of ice or snow, the use of special cold packs or compression devices (using ice water or cooled water; 10-25 degrees C), cold water baths (hydrotherapy) or cooling topical sprays. These techniques utilize conduction and convection as means of cooling affected areas. General guidelines include the need to protect the skin from cold injury via a layer of intervening material, and limiting exposures to twenty minutes. A convenient schedule is alternating twenty minute periods of application and removal.

Skin and superficial fat is readily cooled by surface cryotherapy, but the effects on deep tissues like muscle and tendon, are somewhat debatable. There is agreement that cooling of underlying muscle requires prolonged exposure exceeding twenty minutes, increasing the risk to the skin. As expected, rewarming of successfully cooled deep tissues takes longer that that of the skin and subcutaneous tissue. Typically, with application of ice, one will experience initial intense cold, then burning sensation, followed by aching and finally, pain relief or anaesthesia (loss of sensation).

Specific techniques useful to runners include direct application of ice to the elevated, injured part, often in combination with elastic wraps or compression devices. Ice massage is a very useful modality: paper or Styrofoam cups containing ice provide a convenient tool, making small overlapping circles of four to six inches for twenty minutes.

Problems with cryotherapy include hypersensitivity and allergic reactions (noted if cold and burning sensations last longer than several minutes), and cold injury, i.e.- frostnip and frostbite. Cryotherapy must be avoided in people with rheumatoid arthritic variants with cold sensitivity, those with skin sensation problems, Raynaud’s phenomenon, cryoglobulinemia, Buerger’s disease, and prior history of frostbite, etc. Caution is necessary when applying cold on or near superficial nerves, or when vigorous activity is expected soon after treatment, especially with prolonged treatment aimed at deeper tissues, such as muscle.

Time to chill…next time, heat therapy will be reviewed.


HEAT and Cold Therapy

This discussion will focus on the use of therapeutic heat. As with cold therapy, warm temperature applications have four main effects on body tissues, including pain relief (analgesia), muscle relaxation, blood vessel alterations, and connective tissue relaxation effects. Heat therapy can have both beneficial as well as adverse effects on the tissues, depending upon the magnitude and duration of application.

It is not well known how heat administration reduces pain, but perhaps it is by altering pain nerve fiber conduction speeds, or raising nerve pain thresholds. Furthermore, pain secondary to muscle spasm can be alleviated by direct heat application to tender spastic muscle areas. It is wise to wait until after the acute stages of injury and inflammation subside however, as heat applied early when swelling is prominent can actually increase pain and swelling because of the effects of heat on the blood vessels. Specifically, heat causes a relaxation of blood vessel smooth muscle, thereby opening the vessels and increasing blood flow to the injured region. This phenomenon, combined with direct inflammatory effects, particularly within the skin, mandate a delay in treatment of muscle injury until after swelling resulting from muscle injury has begun to subside. Beneficial effects of increased blood flow to the tissues include facilitation of drainage and a "wash-out" effect, purging the tissues of debris and by-products of tissue injury.

Following muscle, tendon and ligament damage, these tissues generally undergo shortening because of guarded joint positioning due to pain, swelling, and muscle spasm. Typically, rehabilitative efforts are aimed at gradual restoration of joint motion via stretching and gentle range of motion exercises. Heat therapy promotes "relaxation" via lengthening of the collagen tissues within these structures, and thereby aids tremendously in the stretching process.

Burns must be avoided when using heat therapy. Therefore, this technique is not to be used where damaged or abnormally sensate skin is present. As mentioned earlier, heat can increase bleeding in the face of very recent soft tissue injury, such as muscle strains, traumatic tendonitis, and ligament sprains. It can also increase joint swelling if injury is acute. Furthermore, heat should probably also be avoided in children and in women during pregnancy.

General techniques available to runners include conduction (heat transfer by direct contact) and convection (heat transfer via circulation). Hot packs are a form of conductive treatment. Physical therapists often make use of hydrocollator packs, absorptive packs of silica or gel, warmed in hot water baths to over 70 degrees C, wrapped in thick towels to minimize the risk of burns, and applied for 15-20 minutes. These are useful for treatment of joint stiffness and muscle spasm.

Hydrotherapy and contrast baths are examples of convection treatment. Hot tub or whirlpool use ideally includes turbulent flow with water at 38-45 degrees C for 20-30 minutes. Whole body immersion should be avoided at temperatures greater than 40 C (normal body temperature is <38 C), due to the potential for hypotension. Hydrotherapy is recommended for joint stiffness, sore muscles, and for warm-up. Contrast baths induce alternating periods of vasoconstriction and vasodilation, and as such are useful for relatively subacute afflictions of joints and extremities, e.g.- ankle sprains. Here the affected part is alternated between hot (38-45 C) and cold (10-18 C) baths, usually using something like hot 10 minutes, cold 1minute, hot 4, cold 1, hot 4, cold 1, etc., for about 30 minutes total.

In general, after a pulled muscle, joint sprain, or traumatic tendonitis, when swelling is noted, a good rule of thumb is to use cold therapy for the first 48-72 hours (acute period), or until after swelling and pain have peaked. Thereafter, heat therapy may be more advisable, as one enters the subacute phase (3-7 days), or for prolonged symptoms lasting beyond a week.

                                                                                                        Dan Wnorowski, M.D.

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