The 90/90 Active Knee Extension Test measures how far the client can actively straighten the knee while the hip is held near 90 degrees of flexion. It is commonly used to assess posterior thigh mobility and active knee extension range in a controlled position.
A client may report posterior thigh tightness, limited kicking range, difficulty with hamstring mobility drills or a difference between sides during running preparation. The 90/90 Active Knee Extension Test provides a controlled way to assess active knee extension while the hip remains flexed.
The MAT source identifies this as a Range of Motion article for the 90/90 Active Knee Extension test. (matassessment.com)
Test name: 90/90 Active Knee Extension Test
Also known as: AKE, 90/90 hamstring test, active knee extension test
Purpose: Assess active knee extension with the hip flexed
What it assesses: Active knee extension ROM, posterior thigh mobility context and side-to-side comparison
Equipment: Measurz inclinometer or equivalent inclinometer
Key finding: Knee extension angle or extension deficit
Best used with: Straight Leg Raise, Slump Test, knee extension, hip flexion and hamstring strength tests
Key limitation: Pelvic position, hip position, symptoms and active control can affect results
The 90/90 Active Knee Extension Test is performed with the hip flexed to approximately 90 degrees while the client actively straightens the knee. The final knee position is recorded as an angle or extension deficit.
It is used to assess active knee extension range in a hip-flexed position. It can support posterior thigh mobility tracking, side-to-side comparison and progress monitoring.
The test measures active knee extension ROM with the hip flexed. It does not isolate hamstring length completely, measure hamstring strength or explain the cause of symptoms on its own.
This test is specifically an active ROM test. The client actively extends the knee while the hip is held near 90 degrees. If a passive version is performed, it should be recorded as a different method and not compared directly with active AKE results.
Runners, field sport athletes, dancers, gym clients, hamstring mobility tracking, lower-limb progress monitoring and clients where posterior thigh mobility comparison is useful.
Measurz inclinometer or equivalent inclinometer
Treatment table or mat
Optional support to maintain hip position
Measurz app
Symptom notes
Position the client supine. Flex the test hip to approximately 90 degrees. Stabilise the thigh so the hip remains in position. The movement professional stands beside the test limb and monitors pelvis, hip and knee position.
Ask the client to actively straighten the knee as far as possible without changing hip or pelvic position. Measure the final knee angle or extension deficit using the inclinometer. Record the result in Measurz and repeat on the other side if required.
Ask what the client feels and where. Record posterior thigh stretch, pain, tingling, cramping or other symptoms. Stop if symptoms meaningfully change movement quality or the client cannot maintain the test position.
Record the final knee angle or knee extension deficit. A greater ability to extend the knee generally indicates more available active knee extension in this hip-flexed position.
Interpretation is strongest when the scoring convention is consistent. Record whether the score represents final knee angle, remaining knee flexion or extension deficit.
Evidence level: Level 3, limited exact norms; use practical comparison guidance.
Exact protocol-matched values vary by scoring convention and population. Use baseline comparison, side-to-side comparison, symptom response, active/passive distinction and progress across sessions.
A 2020 study reported good reliability for the AKE test and an MDC95 of 12 degrees in an asymptomatic young adult sample, which means small changes should be interpreted cautiously unless they clearly exceed expected measurement variation. A 2022 study of common hamstring flexibility tests in young adults reported excellent interrater and test-retest reliability across several hamstring flexibility measures, including passive knee extension, while also showing that test choice affects interpretation.
Common errors include allowing the hip to drop, posterior pelvic tilt, measuring the wrong angle, performing a passive movement during an active test, changing scoring convention and ignoring symptom response.
Use this test to monitor posterior thigh mobility, compare sides, track response to mobility programming and decide whether straight leg raise, slump, hamstring strength or sprint-related testing would add useful context.
Record baseline score in degrees, side tested, active ROM, hip position, pain score, symptom location, scoring convention, device used, compensation notes, comparison with the other side, related strength findings, related functional findings, progress across sessions and retest date.
Straight Leg Raise Test
Slump Test
Knee Extension Test
Hip Flexion Test
Hamstring Bridge Endurance Test
Sprint Tests
It measures active knee extension ROM while the hip is held near 90 degrees of flexion.
It is commonly used to add context to posterior thigh mobility, but it is not an isolated hamstring measure.
The 90/90 AKE is active by definition. Passive testing should be labelled separately.
Use the same hip position, device placement, scoring convention and Measurz fields each time.
The 90/90 AKE measures active knee extension with the hip flexed.
Hip and pelvis position must be controlled.
Record the scoring convention clearly.
Symptoms should be documented.
Use side comparison and progress tracking in Measurz.
Liu, H., Shen, Y., Xiong, Y., Zhou, H., Mao, Y., Zhang, Z., & Jia, Y. (2022). Psychometric properties of four common clinical tests for assessing hamstring flexibility in young adults. Frontiers in Physiology, 13, 911240. https://doi.org/10.3389/fphys.2022.911240
Olivencia, O., Godinez, G. M., Dages, J., Duda, C., Kaplan, K., & Kolber, M. J. (2020). The reliability and minimal detectable change of the Ely and Active Knee Extension tests. International Journal of Sports Physical Therapy, 15(5), 776–782. https://doi.org/10.26603/ijspt20200776
