Effectiveness of hamstring stretching using a pressure biofeedback unit for 4 weeks: A randomized controlled trial.

Background: Stretching and length test of hamstring muscles have been performed commonly to manage lower back pain (LBP) in sports rehabilitation. Previous literatures addressed that stretching techniques and length test of hamstring muscles should be performed with the pelvic maintained in an anterior tilt position. However, there is no study to determine the effectiveness of pressure biofeedback unit (PBU) to maintain in anterior pelvic tilting (APT) on length test and stretching of hamstring muscles.

Objective: To determine the effectiveness of hamstring muscles stretching using a PBU.

Methods: Forty participants with shortness of hamstrings randomized into two groups. Participants performed the active knee extension (AKE) stretching without (control group) or with PBU (intervention group) for four weeks. AKE tests without and with PBU were administered three times before and after hamstrings stretching by each group.

Results: The AKE test without PBU showed a significant main effect of time ( $p<0.01$ ) but not of group ( $p=0.55$ ) on the AKE angle. The AKE test with PBU showed a significant increase in the AKE angle in the post-intervention compared to the pre-intervention assessments in both groups ( $p<0.01$ ). The difference of AKE angle between the pre- and post-intervention results was significantly greater in the intervention group than in the control group ( $p<0.01$ ).

Conclusion: We recommend the use of a PBU to maintain the pelvic anterior tilting position when performing the AKE test or AKE stretching.