Which of the following is NOT an example of a superficial heating agent?

• A. Continuous uninterrupted ultrasound
• B. Hot packs
• C. Air activated heat wraps
• D. Fluidotherapy

Answer: (A)

Superficial heating agents raise temperature mainly in the skin and the tissues just below it, typically through conduction or convection, to depths of roughly 1–2 cm. Continuous ultrasound heats mainly through acoustic energy that is converted to heat as it travels through tissues, and it tends to penetrate deeper layers, warming muscles and joints more than the superficial skin. Because its primary effect is deeper tissue heating rather than surface warming, ultrasound is not considered a superficial heating agent. Hot packs, air-activated heat wraps, and fluidotherapy are designed to heat the surface of the body and the shallow tissues, making them classic superficial heat sources.