Final answer:
Thermal modalities transfer heat due to temperature difference, relieve pain and improve flexibility in muscles, and help avoid tissue damage caused by overheating and cavitation during treatments like ultrasound diathermy.
Step-by-step explanation:
Thermal modalities have three key functions:
- Transfer heat solely because of a temperature difference.
- Relieve pain and improve flexibility in injured or overworked muscles through deep-heat treatments like ultrasound diathermy.
- Avoid tissue damage caused by overheating and cavitation, which can occur during ultrasound diathermy.