The Long Term Effects of Short-Wave Diathermy and Long-Duration Static Stretch on Hamstring Flexibility

THE LONG TERM EFFECTS OF SHORT-WAVE DIATHERMY AND LONG-DURATION STATIC STRETCH ON HAMSTRING FLEXIBILITY Daniel J. Graham Department of Exercise Sciences Master of Science Objective: To compare changes in hamstring flexibility from treatments of pulsed shortwave diathermy and prolonged stretch versus sham diathermy and prolonged stretch and control and to observe how long those changes last. Background: Heat and stretch techniques have been touted for years. To date, the effect of short-wave diathermy and hamstring stretching has not been thoroughly studied. Because diathermy heats a large area and penetrates deep into the muscle, use of this device prior to or during hamstring stretching may increase flexibility and these gains may last longer. Study Design: A randomized, counterbalanced 3x2x6 repeated measures design. The 3 independent variables were day, pretest/posttest, and treatment mode. Treatment mode had 3 levels: diathermy and stretch, sham diathermy and stretch, and control. The dependent variable was the change in knee extension range of motion (ROM). Methods and Measures: Thirty college-age students with tight hamstrings (inability to achieve >160° knee extension at 90° hip flexion) participated. Subjects were assigned to 1 of 3 groups, (diathermy and stretch; sham diathermy and stretch; control). Range of motion was recorded before and after each treatment every other day for 2 weeks. Additional ROM measures were taken on days 15, 22, 29, and 36. A straight-leg raise stretch was performed using a mechanical apparatus. Subjects in the diathermy and stretch group received 10 minutes of diathermy (distal hamstrings), 5 minutes of diathermy and stretch, followed by 5 minutes of stretching only. Subjects in the sham diathermy and stretch group followed the same protocol, except the diathermy unit was turned off. Subjects in the control group lay on the table for 20 minutes. Data were analyzed using an ANOVA, an ANCOVA, and post hoc t-tests. Results: Least Squares (LS) Mean (± Pooled SE) increases in knee extension after 6 treatments were: 11.3 ± 1.2° for the diathermy and stretch group; 10.0 ± 1.2° for the sham diathermy and stretch group; and 3.2 ± 1.2° for the control group. At Day 15, 3 days after the last treatment, the diathermy and stretch group lost 6.9 ± 0.8°; the sham diathermy and stretch group lost 6.6 ± 0.8°; and the control group changed 1.6 ± 0.8°. At Day 22 the diathermy and stretch group had lost 7.4 ± 0.8°; the sham diathermy and stretch group lost 6.8 ± 0.8°; and the control group changed 1.7 ± 0.8° from the last treatment. At Day 29 the diathermy and stretch group had lost 8.2 ± 0.9°; the sham diathermy and stretch group lost 7.1 ± 0.9°; and the control group changed 1.7 ± 0.8° from the last treatment. At Day 36 the diathermy and stretch group had lost 8.3 ± 0.8°; the sham diathermy and stretch group lost 7.4 ± 0.8°; and the control group changed 2.1 ± 0.8° from the last treatment. Conclusion: These results indicate that hamstring flexibility can be improved when longduration or prolonged stretching is used and that those improvements will slowly diminish over several weeks. Clinicians should consider the use of long-duration stretch to help patients with tight hamstrings increase flexibility and maintain those gains over time. ACKNOWLEDGEMENTS I would first of like to thank my committee for their expertise and guidance through this study. I would also like to thank them for their patience. Special thanks go to those who gave of their time to serve as either a subject or assistant. I would like to thank my wife for her love, patience, support, and also for setting the example. Thank you sweetie. Lastly I want to thank my kids for serving as the motivation to finish.