Local “superficial heating” is recommended in sub acute conditions for reducing pain, increasing tissue elasticity and promoting healing of injured tissue. The most common applications of superficial heat in the clinic are by hydrocollator packs (moist heat) and paraffin bath, a liquid form of heat combining paraffin wax and mineral oil (commonly used for arthritic hands and feet). These basic applications of heat are simple and effective ways to relieve joint pain and residual swelling associated with injury, reduce muscle spasms associated with low back and neck strain, and help increase flexibility of tight muscles that are a result of skeletal muscle (eg., hamstring, quadriceps) strain.
The physical therapist may also use ultrasound to produce a “deep heating” effect in tissues high in collagen, such as tendons, muscles, ligaments, and joint capsules. The deep heating effects of ultrasound have been shown to decrease joint stiffness, reduce muscle spasms, increase blood flow and decrease chronic inflammation.