The Knee Extension Test measures how far the knee can straighten. It is useful for tracking knee extension ROM, comparing sides and adding context to gait, squatting, running, strength work and lower-limb movement.
A client may feel unable to fully straighten the knee, walk with a slight bend, or struggle to reach a comfortable lockout during lower-limb strength exercises. The Knee Extension Test provides a repeatable way to measure knee straightening ROM and track progress across sessions.
The MAT article describes the client lying supine with both legs straight, placing the inclinometer midway along the tibia and asking the client to push the leg down into the table or mat. It also notes that passive testing may be used if recorded. (matassessment.com)
Test name: Knee Extension Test
Purpose: Assess knee extension range of motion
What it assesses: The ability to straighten the knee
Equipment: Measurz inclinometer or equivalent inclinometer
Key finding: Knee extension angle in degrees
Best used with: Knee flexion, 90/90 Active Knee Extension, prone heel-to-butt, gait, squat and sit-to-stand assessment
Key limitation: Extension ROM does not explain the cause of restriction on its own
The Knee Extension Test measures how close the knee gets to full extension or hyperextension. The MAT protocol uses a supine position and tibial inclinometer placement. (matassessment.com)
It is used to establish baseline knee extension, compare sides, track progress and add context to gait, running, squatting and strength testing.
It measures knee extension ROM in degrees. It does not measure quadriceps strength, pain source, swelling, gait quality or full lower-limb function.
Active knee extension is measured when the client straightens or presses the leg down. Passive ROM may be measured when the movement professional assists the knee into extension. Record the method used and avoid comparing active and passive scores as the same result.
Athletes, runners, gym clients, older adults, lower-limb monitoring, gait assessment and clients where knee extension comparison is relevant.
Measurz inclinometer or equivalent inclinometer
Treatment table or mat
Measurz app
Optional towel support if used consistently
Notes for active/passive method and symptoms
Position the client supine with both legs straight. Place the inclinometer midway along the tibia. The movement professional stands near the test leg where device placement can be controlled.
Ask the client to push the leg down into the table or mat to reach available extension. Record the maximal angle in Measurz. If testing passively, apply gentle assistance and clearly record that passive testing was used. Repeat on the other side if needed. (matassessment.com)
Ask the client what they feel and where. Stop if symptoms meaningfully change movement or if the client cannot stay relaxed and controlled.
Record the knee extension angle in degrees. The MAT article states that movement professionals are generally aiming for at least 0 to -10 degrees of knee extension and notes individual variation. (matassessment.com)
A lower extension result may add context to gait, squatting or running, but should be interpreted with symptoms, side comparison, knee flexion ROM, strength and functional movement findings.
Evidence level: Level 2, related or closest available reference values.
The MAT article provides a practical reference of 0 to -10 degrees. Use this cautiously because some clients naturally have more or less hyperextension. (matassessment.com)
Knee extension ROM can be affected by device placement, passive pressure, active effort and how hyperextension is recorded. A 2020 study of ROM tests found strong reliability when standardised procedures were used, while a 2025 lower-limb ROM review highlighted wide variation across tools and protocols.
Common errors include inconsistent inclinometer placement, failing to record hyperextension direction, changing passive pressure, not recording symptoms, allowing hip rotation and comparing active and passive scores directly.
Use the Knee Extension Test for baseline testing, side comparison, progress tracking, gait context, lower-limb exercise programming and monitoring changes across sessions.
Record baseline knee extension ROM in degrees, side tested, active or passive ROM, pain score, symptom location, hyperextension if present, test position, device used, comparison with the other side, progress across sessions, related strength findings and related functional findings.
Knee Flexion Test
90/90 Active Knee Extension Test
Knee Prone Heel-to-Butt Test
Gait Assessment
Single-Leg Sit-to-Stand
Squat Assessment
The MAT article lists 0 to -10 degrees as a practical reference, but individual variation should be expected. (matassessment.com)
Position the client supine, place the inclinometer along the tibia and record the angle as the client straightens the knee.
Either can be useful. Label the method clearly and use the same method for retesting.
It provides movement information and should be interpreted with pain, symptoms, side comparison, strength and function.
The Knee Extension Test measures knee straightening ROM.
Record active or passive method.
Use 0 to -10 degrees as a practical reference, not a universal rule.
Compare both sides where relevant.
Track symptoms and progress in Measurz.
Canever, J. B., Nonnenmacher, C. H., & Lima, K. M. M. (2025). Reliability of range of motion measurements obtained by goniometry, photogrammetry and smartphone applications in lower limb: A systematic review. Journal of Bodywork and Movement Therapies. Advance online publication. https://doi.org/10.1016/j.jbmt.2025.01.009
Fraeulin, L., Holzgreve, F., Brinkbäumer, M., Dziuba, A., Friebe, D., Klemz, S., et al. (2020). Intra- and inter-rater reliability of joint range of motion tests using tape measure, digital inclinometer and inertial motion capturing. PLOS ONE, 15(12), e0243646. https://doi.org/10.1371/journal.pone.0243646
Kiatkulanusorn, S., Luangpon, N., Srijunto, W., Watechagit, S., Pitchayadejanant, K., Kuharat, S., Anwar Bég, O., & Paepetch Suato, B. (2023). Analysis of the concurrent validity and reliability of five common clinical goniometric devices. Scientific Reports, 13, 20915. https://doi.org/10.1038/s41598-023-48344-6
