STUDY DESIGN: Randomized controlled trial with pretraining, posttraining, and follow-up repeated measures. OBJECTIVE: To determine the effectiveness of a 4-week elastic resistance exercise program on balance in subjects with and without a history of sprained ankles. BACKGROUND: Several researchers have suggested that improving balance may help alleviate the symptoms of functional ankle instability and reduce the rate of recurrent ankle sprains. METHODS AND MEASURES: Forty subjects (20 males, 20 females; 20 subjects with chronic ankle instability [CAI], 20 healthy) participated in the study. Ten subjects (5 males, 5 females) from each CAI and healthy group were randomly assigned to either the exercise or control group, resulting in a total of 4 groups. Total travel distance of the center of pressure, monitored using a force platform, was measured before training, after 4 weeks of training, and at a 4-week follow-up. RESULTS: There were no interactions between gender, ankle sprain history, or training groups. Balance significantly improved in subjects with and without a history of ankle sprains following 4 weeks of elastic resistance exercises. Mean improvement in balance for the exercise group following training, reflected through a decrease in total travel distance, was −11.1 cm (95% confidence interval: −14.0 to −8.2 cm). These improvements in balance were retained 4 weeks after training. CONCLUSIONS: Balance was improved after 4 weeks of elastic resistance exercise in subjects with and without a history of lateral ankle sprains. Balance improvements persisted 4 weeks following the treatment cessation. LEVEL OF EVIDENCE: Therapy, level 2b.

J Orthop Sports Phys Ther 2009;39(4):246-255, Epub 17 December 2008. doi:10.2519/jospt.2009.2958

KEY WORDS: ankle, chronic ankle instability, sprain, stabilometry

Study Design: A repeated-measure crossover design was used. The independent variable was the type of ultrasound (pulsed or continuous) and the dependent variable was intramuscular temperature. Objective: To compare changes in intramuscular temperature resulting from the use of pulsed ultrasound versus continuous ultrasound with an equivalent spatial average temporal average (SATA) intensity. Background: There is a lack of research on the heat-generating capabilities of pulsed ultrasound within human muscle. Methods and Measures: The subjects were 16 healthy volunteers (mean age ± SD, 21.3 ± 2.5 years). Each subject was treated with pulsed ultrasound (3 MHz, 1.0 W/cm ₂, 50% duty cycle, for 10 minutes) and continuous ultrasound (3 MHz, 0.5 W/cm ₂, for 10 minutes) during a single testing session. Tissue temperature returned to baseline and stabilized between treatments and treatment order was randomized. Tissue temperature was measured every 30 seconds using a 26-gauge needle microprobe inserted at a depth of 2 cm in the left medial gastrocnemius muscle. Data were analyzed using a linear mixed model. Results: Treatment with continuous ultrasound produced a mean (±SD) temperature increase of 2.8°C ± 0.8°C above baseline. Treatment with pulsed ultrasound produced a mean (±SD) temperature increase of 2.8°C ± 0.7°C above baseline. Statistical analysis revealed no significant differences in either the extent or rate of temperature increases between the 2 modes of ultrasound application. Conclusion: Pulsed ultrasound (3 MHz, 1.0 W/cm ₂, 50% duty cycle, for 10 minutes) produces similar intramuscular temperature increases as continuous ultrasound (3 MHz, 0.5 W/cm₂, for 10 minutes) at a 2-cm depth in the human gastrocnemius. Spatial average temporal average intensity is an important consideration when selecting pulsed ultrasound parameters intended to deliver nonthermal effects.

J Orthop Sports Phys Ther. 2004;34(7):395-401. doi:10.2519/jospt.2004.1363 

Key Words: heat, physical agents, spatial average temporal average intensity