Abstract
Research on therapeutic ultrasound has not focused on the duration needed to cause thermal change with various ultrasound intensities. Objective: To analyze triceps surae intramuscular temperature using 4 intensity levels after a 10-min 1-MHz continuous ultrasound treatment at a depth of 4 cm. Design: 1 × 4 repeated measures. Independent variable: intensity of 4 levels—0.5, 1.0, 1.5, and 2.0 W/cm². Dependent variable: peak intramuscular temperature. Setting: Research laboratory. Participants: 19 volunteers with no lower leg pathologies. Intervention: Treatment order was balanced via Latin square and performed 24 hr apart. Main Outcome Measures: Peak intramuscular temperatures. Results: The only significant difference detected was that the mean temperature after the 1.0-W/cm² treatment (37.3 °C) was greater than that at 2.0-W/cm² intensity (36.1 °C). No treatment reached the desired 4° increase needed for therapeutic efficacy. Conclusions: Treatments at 1.0 W/cm² increased tissue temperatures more than those at 2.0 W/cm².