The most useful of heat therapy after sports injury consist of: immersion in hot water, hot packs, paraffin-wax baths and electric pads. Heat therapy must not be used immediately after an injury, but should be delayed for at least 12 to 24 hours. It causes a dilatation of the capillaries of the part under heat therapy, and if used too soon aggravates the inflammatory reaction and encourages bleeding from the torn blood vessels. The application of heat to an injured part relieves pain and muscle spasm, through its effects on the nerve endings in the skin. This is particularly true of the moist forms of heat, e.g. paraffin-wax and hot packs. Heat also assists in the repair process by increasing the blood supply to the injured area.
Simple heat therapy have a direct heating effect on the skin, heating of the structures which lie immediately beneath the skin, such as ligaments, is possible to a limited degree by conduction, i.e. the temperature of the skin is raised and the adjacent tissues absorb some of the heat. Short-wave diathermy and ultrasonic therapy are capable of heating the deeper structures after sports injury.
Immersion in hot water
The heat penetrates the skin to a small degree only, and the heating effect on the deeper tissues is negligible. Generally the treatment Is used only when other forms of heat therapy are not available. Immersion time: 20 to 30 minutes.
Hot packs
The heating effect after sports injury is again superficial. Hot packs are widely used, however, because they form a very simple and practical method of applying moist heat in the relief of pain. The toweling pack has now been largely superseded by the steam pad. This pack is inexpensive, and can be easily used at home by the player. It consists of a thick linen pad, 12x10 in., which contains special filler which absorbs up to three times its own volume of water. It is stitched into several sections, so that it is flexible and can be molded to any part of the body.
The pad is placed in a saucepan of hot water, and boiled for about 30 minutes. It is next lifted out of the water by the loops which are attached to each corner, and wrapped in four or five thicknesses of Turkish toweling. The pad is then placed on the injured part, and covered with two or more layers of toweling to conserve heat. The top towel is usually wound round the area being treated, to hold the pack firmly in place. The pack is left in position for about 20 to 30 minutes.
Sheets of foam rubber, 1/2 in. thick, may be used to replace the towels after sports injury, this heat treatment simplifies application. After being boiled, the pad is laid on a piece of foam rubber, which is folded over it. A towel is placed over the injured part, and covered by another piece of foam rubber. The pack is placed on top of the rubber square, and held in place by a towel. The foam rubber can be used a great many times before it needs to be replaced.
Paraffin-wax baths
When a wax bath is used the heating effect is slightly greater than that produced by the two previous treatments after sports injury. If the wax is applied as a pack the heating effect is not so pronounced. Wax baths are only suitable for injuries of the hands, wrists, elbows, feet and ankles.
The wax is usually heated to a temperature of between 110°F. and 120°F, and it is best to use a wax with a low melting point (110°K). A wax pack is made by using a 2 in. paintbrush, and applying six to eight coats of hot wax to the affected area; the wax may also be applied with a soup ladle. The part is then covered with grease-proof paper, well wrapped in a large piece of old blanket, and left for about 20 to 30 minutes.
Electric pads
Superficial heating only, as with the hot pack after sports injury, the dry form of heat produced by an electric pad is not so effective in relieving pain as moist heat.
