Abstract
It has been suggested that to obtain optimal physiological effects of heating, musculoskeletal temperature (TEMP) should be elevated 3 °C above baseline and maintained for at least 5 min. Objective: To identify a multi-intensity ultrasound protocol that will achieve optimal heating. Design: 1 × 2 between-subjects. Setting: Sports-injury research laboratory. Participants: 20 healthy volunteers. Interventions: A 2.5-mm treatment at 2.4 W/cm² immediately followed by a 7.5-min treatment at 1.0 W/cm² (T1) and a 10-min treatment at 1.5 W/cm² (T2). Outcome Measures: TEMP change during the first 2.5 mm of ultrasound treatment (°C), time the TEMP was ≥3 °C above baseline during and after the treatment. Results: T1 increased TEMP during the first 2.5 mm of the ultrasound treatment (3.22 ± 1.25 °C) more than T2 did (1.68 ± 0.72 °C). No difference was found for the remaining measures. Conclusions: The multi-intensity protocol (2.4 W/cm² and 1.0 W/cm²) did not result in optimal heating.