What distinguishes superficial heat modalities from deep heat modalities?

Superficial heat modalities are characterized primarily by their application of heat to the surface of the skin, which then increases the temperature of the underlying tissues to a limited depth, typically up to 1-2 cm. The correct choice highlights that superficial treatments can utilize dry heat sources such as heating pads or infrared lamps. These methods are effective at promoting local blood circulation, alleviating pain, and relaxing muscles in areas that receive the heat.

In contrast, deep heat modalities, like ultrasound or diathermy, penetrate more significantly into the tissues, promoting therapeutic effects at greater depths, usually greater than 2 cm. Typically, deep heat modalities may also incorporate moist heat methods, but the defining characteristic of superficial modalities remains their application on the skin surface with dry or sometimes moist applications.

Hence, the distinction lies in the depth of tissue heating and the type of heat being applied, with superficial modalities generally utilizing dry heat applications. This understanding clarifies why the correct choice refers specifically to dry heat in reference to superficial treatments.