Effects of Altering Intensity during 1-MHz Ultrasound Treatment on Increasing Triceps Surae Temperature

Abstract

Context: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-min 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 min 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 min 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.