The Ankle Eversion Strength Test measures the maximum isometric force produced when the client pushes the outside of the foot against the Anker. It is used to objectively assess ankle evertor strength, monitor changes over time and compare left and right limbs using a consistent testing setup.
The primary muscles assessed include the fibularis longus, fibularis brevis and fibularis tertius. These muscles contribute to lateral ankle stability, foot positioning during gait, balance and change-of-direction movements.
When used with Measurz, the Anker can record peak force and additional force-time metrics including force relative to body weight, impulse, torque (when the lever arm is entered), rate of force development, time to peak and fatigue index.
The assessment measures strength only and should always be interpreted alongside symptoms, functional performance and other assessment findings.
The client performs a maximal isometric ankle eversion contraction by pushing the outside of the foot into the Anker without allowing visible movement at the ankle.
Because the Anker provides fixed resistance using four independent load cells, testing is highly repeatable when the same client position, foot placement and load cell contact are reproduced.
Explain that the assessment measures how strongly they can push the outside of their foot into the Anker.
Record any pain, swelling, stiffness, recent injury, neurological symptoms or fatigue before testing.
Allow one or two practice contractions so the client becomes familiar with the movement.
Seat the client with:
hips flexed approximately 90°
knees flexed approximately 90°
pelvis against the backrest
trunk upright
feet facing forwards
Maintain the same position during every reassessment.
Place the testing foot so that:
the heel is centred on the footplate
the second metatarsal aligns with the centre of the platform
the ankle begins in a neutral position
the tibia remains vertical
Position the lateral load cell against the lateral border of the fifth metatarsal head. Avoid contact with the lateral malleolus or toes.
Record the exact setup so it can be reproduced during future testing.
Prevent movement of the pelvis, knee and trunk throughout the contraction.
Only the ankle should generate force against the load cell.
Use consistent verbal cues.
"Push the outside of your foot into the pad."
"Build the pressure smoothly."
"Push as hard as you can."
"Hold."
"Keep breathing."
Use:
1–2 practice trials
2–3 maximal trials
3–5 second contraction
30–60 seconds rest
Record either the highest value or the average of the recorded trials and use the same method at every retest.
the heel lifts
the foot rotates
the knee moves
the trunk leans
the load cell loses contact
pain limits maximal effort
the client starts before instructed
The assessment may assist with:
baseline ankle strength assessment
left versus right comparison
monitoring rehabilitation progress
athlete profiling
lower-limb strength assessment
objective progress tracking
monitoring response to exercise
performance testing
It should not be used as a stand-alone diagnostic or return-to-sport assessment.
The primary outcome is peak isometric ankle eversion force.
When analysed in Measurz, additional metrics may include:
Peak force
Force relative to body weight
Impulse
Torque
Rate of force development
Time to peak
Fatigue index
The assessment does not directly measure ankle stability, ligament integrity, tendon pathology, range of motion, balance or gait quality.
Higher force values generally indicate greater ankle eversion strength in the tested position.
Lower force values may be influenced by pain, fatigue, apprehension, previous injury, reduced effort or inconsistent positioning.
When interpreting the assessment:
Compare with the client's previous results.
Compare the left and right limbs.
Consider symptoms during testing.
Review movement quality and compensations.
Relate the findings to functional goals.
Published Anker-specific normative values are currently unavailable.
Research using handheld and fixed dynamometry demonstrates that ankle eversion strength can be measured reliably when the testing position is standardised, although force values vary considerably between protocols and devices. For this reason, baseline measurements and repeated testing using the same protocol are generally more valuable than comparing absolute values with other studies.
Healthy adults typically demonstrate less than a 10% side-to-side difference in ankle strength. Larger asymmetries may warrant further assessment when they correspond with symptoms or functional limitations.
Youth: Use additional practice trials and interpret results relative to growth and physical development.
Adults: Useful for baseline assessment and monitoring changes over time.
Older adults: Consider results alongside walking ability, balance and daily function.
Athletes: Assess as part of a broader lower-limb strength profile for running, jumping, cutting and landing activities.
Clients with persistent symptoms: Interpret findings alongside pain, confidence and functional performance rather than strength alone.
Common errors include:
inconsistent foot placement
heel lifting
excessive toe gripping
trunk movement
pelvis shifting
incorrect load cell contact
inconsistent verbal instructions
Limitations include:
results are specific to the testing setup
pain may reduce force production
strength alone does not determine functional performance
published Anker-specific normative data are currently limited
The assessment is useful for:
establishing a baseline
monitoring progress over time
comparing left and right limbs
athlete screening
lower-limb strength profiling
objective reporting in Measurz
client education
Maximum isometric ankle eversion strength.
Peak force is the primary outcome measure.
No. It measures strength only.
Yes. Bilateral comparison is recommended.
Small changes in foot position or load cell contact can significantly influence force measurements.
Measures maximal isometric ankle eversion strength.
Peak force is the primary outcome.
Four independent load cells provide repeatable testing conditions.
Standardised positioning improves consistency.
Compare results with previous assessments and the opposite limb.
Interpret strength alongside symptoms and function.
Alfuth, M., & Hahm, M. M. (2016). Reliability, comparability, and validity of foot inversion and eversion strength measurements using a hand-held dynamometer. International Journal of Sports Physical Therapy, 11(1), 72–84.
Mentiplay, B. F., Perraton, L. G., Bower, K. J., Adair, B., Pua, Y. H., Williams, G. P., McGaw, R., & Clark, R. A. (2015). Assessment of lower limb muscle strength and power using hand-held and fixed dynamometry: A reliability and validity study. PLOS ONE, 10(10), e0140822.
World Journal of Orthopedics. (2025). Normative values of ankle strength and its importance for rehabilitation and return to sport.
