Measuring hamstring flexibility is important for determining the outcome of injury treatment and monitoring the recovery process. Research has shown that the active knee extension test (AKET) and passive knee extension test (PKET) are reliable in the case of healthy subjects but data has so far been lacking on the effectiveness of these tests in people with acute hamstring injuries. A team of Dutch researchers sought to fill that gap, establishing that the AKET and PKET are also reliable in the latter case.
The group of researchers was led by Dr. Gustaaf Reurink from the Erasmus Medical Center in Rotterdam. The study itself took place at the Department of Sports Medicine of The Hague Medical Center, the University Medical Center in Utrecht and the Royal Dutch Football Association. The findings have been published in the American Journal of Sports Medicine.
Although the AKET and PKET are painful and cause discomfort during application, it seems that they are worth the trouble, the researchers concluded. For the purposes of their study, they recruited 50 athletes suffering from acute hamstring injuries as confirmed through MRI. Within five days of the injury, each subject underwent the AKET and PKET. The researchers determined intraclass correlation coefficient (ICC), standard error of measurement (SEM) and minimal detectable difference (MDD). As they point out in the study abstract, the ICC of the AKET in the injured leg was 0.89, while the figure for PKET was 0.77. The SEM was 5.3° and 7.6° respectively for the AKET and the PKET, while MDD was determined at 15° and 21° respectively. The team was led to conclude that both tests were reliable tools for measuring flexibility in injured hamstrings.