What type of application provides a mechanical effect on the skin?

The correct answer is based on the fact that cold mitten treatments create a mechanical effect on the skin through the application of a specific technique. During this treatment, one hand is submerged in a cold water solution, while the other hand is applied to the skin, resulting in a striking mechanical stimulation due to the temperature difference and the physical movement involved. This technique can improve circulation and trigger sensory receptors in the skin, thereby enhancing treatment outcomes.

The other options pertain more to thermal effects or energy transfer rather than mechanical effects. For example, thermal packs are primarily used for their heat-retaining properties to alleviate stiffness and pain, rather than providing a direct mechanical effect. Ultrasound therapy uses sound waves to produce changes in tissue at a cellular level, focusing on healing rather than mechanical manipulation. Meanwhile, hot stone therapy involves the application of heated stones to create warmth and relaxation in muscles, which again emphasizes thermal rather than mechanical effects. This distinction highlights why cold mitten treatments are classified based on their mechanical action on the skin.