Which of the following is NOT a superficial heating agent?

Which of the following is NOT a superficial heating agent?

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

Answer: (A)

Heating depth matters. Superficial heating methods warm mainly the skin and just under it, transferring heat by conduction from a hot surface or chemical reaction. Continuous ultrasound, on the other hand, uses acoustic energy that is absorbed inside the tissues and converted to heat within deeper layers (muscle and beyond), especially at therapeutic frequencies. That internal heating makes it a deep heating modality, not superficial. Hot packs, air-activated heat wraps, and paraffin rely on surface heat transfer to the skin and only a limited depth, so they are considered superficial heating agents.

Heating depth matters. Superficial heating methods warm mainly the skin and just under it, transferring heat by conduction from a hot surface or chemical reaction. Continuous ultrasound, on the other hand, uses acoustic energy that is absorbed inside the tissues and converted to heat within deeper layers (muscle and beyond), especially at therapeutic frequencies. That internal heating makes it a deep heating modality, not superficial.

Hot packs, air-activated heat wraps, and paraffin rely on surface heat transfer to the skin and only a limited depth, so they are considered superficial heating agents.