| Pulsed shortwave diathermy (PSWD) is an electromagnetic thermal modality used in the clinical setting. It is believed that temperature increases associated with PSWD in combination with stretch may reduce stiffness and increase tissue compliance. Our objective was to assess the short-term effects of PSWD and stretch on the torque-angle relation of the triceps surae muscles when passive stretch is applied both during and after PSWD treatment. We used a 3 X 4 (Time X Treatment) and a 2 X 4 (Time X Treatment) crossover repeated measure designs in this study. The independent variables were condition (stretching during diathermy, stretching after diathermy, and stretching during and after diathermy treatment) and time (pre, post, 15-minutes post treatment). Alpha was set at 0.05. Data was collected at the University of Texas at Arlington, Department of Kinesiology's Neuromuscular Exercise Science and Research Laboratory. Sixteen males (height, 175.86 +/- 9.13 centimeters; weight 82.30 +/- 17.16 kilograms; age, 22.94 +/- 3.75 years) completed a health history form and signed an informed consent. Dependent variables were energy absorbed, energy returned, peak torque, average stiffness, intramuscular temperature, and average range of motion (ROM). PSWD treatments showed an average increase of 3.51 +/- 0.27°C in intramuscular temperature after 20 minutes of PSWD treatment. Whereas, the control treatment's intramuscular temperature decreased 0.85 +/- 0.30°C after 30 minutes of resting on a plinth. Low-load long duration stretching in combination with PSWD seems to have an effect on and significantly increases tissue compliance. Peak torque and average stiffness decreased (12% and 10%, respectively) from pre to post treatment for all heating and stretch conditions. However, there was a greater increase in tissue compliance during treatments when stretch was applied during tissue cooling. From the results of our study, we now believe that stretch combined with heat does affect tissue compliance and that the best time to stretch is after the tissue has been heated sufficiently and while the tissue is cooling. |
