Interrater and Intrarater Reliability of the Active Knee Extension (AKE) Test among Healthy Adults

[Purpose] The purpose of this study was to determine the reliability of the active knee extension (AKE) test among healthy adults. [Subjects] Fourteen healthy participants (10 men and 4 women) volunteered and gave informed consent. [Methods] Two raters conducted AKE tests independently with the aid of a simple and inexpensive stabilizing apparatus. Each knee was measured twice, and the AKE test was repeated one week later. [Results] The interrater reliability intraclass correlation coefficients (ICC(2,1)) were 0.87 for the dominant knee and 0.81 for the nondominant knee. In addition, the intrarater (test-retest) reliability ICC(3,1) values range between 0.78–0.97 and 0.75–0.84 for raters 1 and 2 respectively. The percentages of agreement within 10° for AKE measurements were 93% for the dominant knee and 79% for the nondominant knee. [Conclusion] The finding suggests the current AKE test showed excellent interrater and intrarater reliability for assessing hamstring flexibility in healthy adults.