Ultrasound heating is curvilinear in nature and varies between transducers from the same manufacturer.

CONTEXT: Ultrasound heating rates are known to differ between various manufacturers; it is unknown whether this difference exists within a manufacturer.

OBJECTIVE: Determine if intramuscular heating differences exist between transducers from the same manufacturer.

STUDY DESIGN: 3 x 10 repeated measures. Independent variables were Transducer (A, B, and C) and Time (10-min time points during the treatment).

SETTING: Controlled laboratory.

PARTICIPANTS: Twelve volunteers (M = 4, F = 8; age: 23 +/- 4 years; calf-girth: 37.94 +/- 4.16 cm; calf-skinfold: 27 +/- 17 mm).

INTERVENTION: Three 10-min 1MHz continuous ultrasound treatments performed at an intensity of 1.2 W/cm2, over an area 2x transducer.

MAIN OUTCOME MEASURES: Calf temperature increase.

RESULTS: Heating curve generated for each transducer were significantly different (P = .034) but the overall temperature increases following 10 minutes of treatment were within 0.1 degree C (F = 1.023 P = .573).

CONCLUSION: Heating curves differ between transducers from the same manufacturer but peak heating at 10 minutes was similar.