EFFECT OF HEAT ON SKIN
Massage is often preceded by application of heat to the involved part. Local heat can be applied in the form of poultices, hot water packs, hot water bottles, electric pads, special electric lamps, chemical pads, paraffin baths, and diathermy. General heat may be used in the form of hot water baths, steam baths, va-por baths, dry thermal cabinets, and electric blankets.
When heat is applied for a short period, it causes peripheral vasodilatation, redness of skin, general and local muscular relaxation, increase in pulse rate and respiratory rate, shallow respiration, decrease in blood pressure, and diminished heat production. Heat opens up vascular channels and softens the tis-sues, permitting more effective application of mas-sage. It stimulates the circulation, speeds removal of inflammation waste products and, thereby, relieves pain, swelling, and spasm.