Developing healthy kids in healthy communities: eight evidence-based strategies for preventing high-risk behaviour.

Australian youth engage in behaviour that threatens their health and wellbeing. National surveys report that about a third of young Australians have tried an illicit drug. High rates of substance use and risky sexual behaviour among young Australians suggest that effective prevention efforts based on empirical evidence need to be expanded. Church-associated organisations are an untapped resource that could be used to improve the health and welfare of young people. We describe eight evidence-based elements to consider in designing strategies to prevent high-risk behaviour in young people.

Effect of transducer velocity on intramuscular temperature during a 1-MHz ultrasound treatment.

STUDY DESIGN: A 3 x 2 repeated-measures design was used. The independent variables were transducer velocity (2-3 cm/s, 4-5 cm/s, and 7-8 cm/s) and time (pretreatment and posttreatment). OBJECTIVE: To determine if transducer velocity of a 1-MHz ultrasound treatment affects intramuscular tissue temperature. BACKGROUND: Most authors advocate ultrasound transducer velocities of 2 to 4 cm/s within an area of 2 to 3 times the effective radiating area or 2 times the size of the transducer head. However, a much faster rate of application (approximately 7-8 cm/s) is often observed in clinical settings. METHODS AND MEASURES: Eleven healthy screened volunteers (9 males, 2 females; mean +/- SD age, 22.6 +/- 1.7 years; mean +/- SD height, 175.7 +/- 13.7 cm; mean +/- SD body mass, 82.5 +/- 19.5 kg) were randomly assigned to a treatment order with all conditions administered during a single testing session. Each transducer velocity condition was administered for 10 minutes, using 1-MHz ultrasound with a 100% continuous duty cycle at an intensity of 1.5 W/cm2 over an area twice the size of the transducer head. After the first treatment, the 2 remaining subsequent velocity conditions were administered after the intramuscular temperature returned to within +/- 0.3 degrees C of the initial pretreatment temperature for 5 minutes. The dependent variable was left triceps surae muscle temperature measured at 3 cm below one half the measured skinfold thickness. RESULTS: Temperature increase across the 3 velocities was within 0.4 degrees C (F2.20 = 0.07, P = .93). Posttreatment values (mean +/- SD) ranged from 42.7 degrees C +/- 2.3 degrees C for the slowest velocity to 43.1 degrees C +/- 1.4 degrees C for the fastest velocity. Temperature increase was significant for time (F1.01 = 155.68, P<.00001), increasing from 37.8 degrees C +/- 0.8 degrees C pretreatment to 42.9 degrees C +/- 1.9 degrees C after treatment. CONCLUSION: Very similar intramuscular temperature increases can be observed among ultrasound treatments (10-minute duration, 1-MHz frequency, 100% continuous duty cycle, 1.5 W/cm2 intensity, within an area twice the size of the transducer head), with transducer velocities of 2 to 3, 4 to 5, and 7 to 8 cm/s.