Effect of Hamstring Stretching on Pelvic Angle and Biofeedback Pressure during Passive Straight Leg Raising

Abstract

Background In clinical settings, a pressure biofeedback unit (PBU) is sometimes used to detect pelvic movement and retrain movement patterns during lower limb movement. Hamstring length influences changes in pelvic movement during passive straight leg raising (PSLR). Purpose To determine the relationship between pelvic motion and biofeedback pressure measured by a PBU during PSLR, and to identify changes in biofeedback pressure after hamstring stretching. Study design Cross-sectional study Methods Twenty participants with short hamstrings were recruited for this study. A three-dimensional motion analysis system and PBU were used to measure pelvic angle and biofeedback pressure during PSLR, respectively. The pelvis angle and biofeedback pressure were measured before and after hamstring stretching, increasing PSLR in 10-degree increments. Results There was a significant relationship between pelvic motion and biofeedback pressure (Pearson’s <italic>r</italic>=0.76, <italic>p</italic>&lt;0.05). Linear regression equation using lumbopevic angle as an independent factor was as follows: Pressure of PBU=45.05+(3.35×angle of lumbopelvic motion) (R²=0.57, <italic>p</italic>&lt;0.05). Biofeedback pressure decreased significantly between PSLR angles of 10–60° after hamstring stretching (<italic>p</italic>&lt;0.05). The pelvic angle decreased significantly at PSLR angles of 50° and 60° after hamstring stretching (<italic>p</italic>&lt;0.05). Conclusions Biofeedback pressure measured with a PBU can be used to assess pelvic motion during muscle length tests following hamstring stretching.