Heating of injured tissue has been used for centuries for pain relief and reduction of muscle spasm. In physical therapy locally applied heating gents are used not only to promote relaxation and provide pain relief, but they are also used to increase blood flow, to facilitate tissue healing, and to prepare stiff joints and tight muscles for exercise. Superficial heating agents primarily cause in increases in skin and superficial cutaneous tissue temperature. Superficial heating agents such as hot packs, paraffin wax, Deep heating agents, including shortwave diathermy and continuous-wave ultrasound, can increase tissue temperature at depths ranging from 3to 5cm without overheating the skim and subcutaneous tissue.