Rectus Femoris Muscle Tightness: Intratester Reliability of an Active Knee Flexion Test

The purpose of this study was to examine the intratester reliability of a test designed to measure tightness in the rectus femoris muscle (RFM). The examiner measured the angle of knee flexion with a pendulum goniometer after active knee flexion with the subject prone and the hips stabilized in extension. The angle of knee flexion represents RFM tightness. After an instruction session, the RFM tightness of both extremities of 20 men was measured during test and retest sessions. The reliability coefficients for test and retest measurements were 0.97 for the left extremity and 0.97 for the right extremity. The author discusses factors that may have contributed to the high reliability, including a well defined and easily observed end point of motion, strict hip stabilization, and accurate instrument placement. If conducted properly, the test should provide clinicians and researchers with an objective and reliable tool for measuring RFM tightness. J Orthop Sports Phys Ther 1985;6(5):289-292.