Repeated passive stretching:: Acute effect on the passive muscle moment and extensibility of short hamstrings

Objective: To examine the response of short hamstring muscles to repeated passive stretching. Design: A repeated measures design. Setting: A university laboratory for human movement analysis in a department of rehabilitation. Subjects: Students (7 men, 10 women) from the Department of Human Movement Sciences. Main Outcome Measures: The lift force, range of motion, pelvic-femoral angle, first sensation of pain, and electromyogram of the hamstrings were measured. Results: Comparison of the data of the test group (n = 17) after five successive passive stretch tests by means of an instrumental straight-leg raising test showed no significant change of the variables passive muscle stiffness and extensibility (P >.05). Conclusion: The acute effect of repeated passive stretching of short hamstring muscles is negligible. With an instrumental straight-leg raising test, the relevant muscle variables can be examined noninvasively. (C) 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.