Neurophysiologic influences on hamstring flexibility: A pilot study

Objective: To examine the potential contribution of neurologic influences o n hamstring length during passive range of motion. Design: Prospective study. Settings: Academic sports medicine center. Patients: 15 subjects undergoing arthroscopic surgery for unilateral knee i njuries without previous injury to the contralateral knee. Interventions: Subjects received: 1) spinal anesthesia with bupivacaine, 2) epidural anesthesia with lidocaine, 3) general anesthesia, or 4) femoral n erve block of injured leg only. Main Outcome Measures: Noninjured leg popliteal angle preoperatively, intra operatively under anesthesia, and postoperatively after recovery from anest hesia. Results: The overall mean popliteal angle was 132.5 +/- 3.1 degrees preoper atively, 134.31 +/- 11.6 degrees intraoperatively, and 130.7 +/- 10.2 degre es postoperatively. Overall, the intraoperative angle was significantly gre ater than the postoperative angle (p = 0.02). The mean change in popliteal angle was 8.1 +/- 2.2 degrees (Group 1), -0.4 +/- 1.9 degrees (Group 2), 0. 9 +/- 1.4 degrees (Group 3), and -2.4 +/- 3.8 degrees (Group 4). There was no significant change in pre- to postoperative popliteal angle in relation to postoperative pain. Females had a greater mean popliteal angle (139.84 d egrees) compared with males (128.84 degrees) (p = 0.04). Clinical Relevance: Understanding the neuromuscular influences on muscle fl exibility will assist in the development of new rehabilitative and injury p reventative techniques. Conclusion: The present pilot study implicates neural contributions to musc le flexibility. Further studies are needed to delineate the relative contri butions of neural and muscular components and to facilitate new techniques in the rehabilitation and prevention of injury.