Hot-Pack and 1-MHz Ultrasound Treatments Have an Additive Effect on Muscle Temperature Increase

Area of Science:

• Physiotherapy
• Therapeutic Modalities
• Muscle Physiology

Background:

• Therapeutic ultrasound is a common deep heating modality.
• Prior heating or cooling can modify ultrasound's effects.
• The triceps surae muscle group is a common target for ultrasound therapy.

Purpose of the Study:

• To investigate the tissue temperature rise in the triceps surae muscle.
• To evaluate the effect of prior heating with a hot pack on ultrasound-induced temperature increase.

Main Methods:

• A 2x2x3 factorial design with repeated measures was employed.
• Independent variables included pack temperature (hot vs. room), measurement depth (1 cm vs. 3 cm), and time.
• Tissue temperature was measured using microprobes in 21 healthy college students.

Main Results:

• Both hot packs and ultrasound resulted in a greater temperature increase (0.8°C) compared to ultrasound alone.
• At 1 cm depth, hot pack preheating led to a 3.8°C rise, with ultrasound adding 0.6°C.
• At 3 cm depth, ultrasound added 3.68°C after hot pack preheating, indicating an additive thermal effect.

Conclusions:

• Preheating with hot packs enhances ultrasound's deep heating effect on muscle tissue.
• Combining hot packs and ultrasound can achieve significant temperature increases more rapidly.
• An additive thermal effect exists, but a tissue temperature plateau may influence the response.