Passive knee extension test to measure hamstring muscle tightness.

The purpose of this study was twofold: (a) to examine the reliability of a test designed to measure tightness of the hamstring muscles, and (b) to assess the pelvic motion during this test. The knee was passively extended by a standardized force, while the hip was stabilized in 120 degrees of flexion. The knee angle was measured with a goniometer and represents the hamstring tightness. Twenty-eight test-retests were performed. The correlation coefficient was found to be 0.99, and the CV was found to be 1%. We used a MacReflex measurement system to assess the associated pelvic motion. Eight measurements were taken, and the median of associated pelvic motion was 4.1 degrees. It is concluded that the passive knee extension test is a simple and reliable method, and the associated pelvic motion is minimal.