Anker: Wrist Extension Strength Test

The Wrist Extension Strength Test measures the maximum isometric force produced when lifting the back of the hand towards the forearm. Using the Anker, the assessment provides an objective and repeatable measure of wrist extensor strength in a standardised position.

Wrist extension strength is critical for grip performance because the wrist extensors stabilise the wrist during forceful gripping. It is also important during lifting, pushing, racquet sports, throwing, climbing, manual handling and many occupational tasks requiring sustained hand function.

The primary muscles assessed include extensor carpi radialis longus, extensor carpi radialis brevis and extensor carpi ulnaris.

When used with Measurz, the Anker records peak force and can calculate additional 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 muscle force only and should always be interpreted alongside symptoms, wrist mobility, grip strength and functional performance.

What Is the Wrist Extension Strength Test?

The Wrist Extension Strength Test is an isometric assessment where the client attempts to lift the back of the hand towards the forearm while maintaining a stable forearm and elbow.

The assessment is typically performed with the elbow flexed to approximately 90°, the forearm supported and the wrist beginning in a neutral position. Standardising the testing position improves consistency between assessments.

The Anker provides fixed resistance, allowing objective and repeatable strength assessment when client positioning, anatomical landmarks and verbal instructions remain unchanged.

Step-by-Step Protocol

1. Prepare the client

Explain that the assessment measures how strongly they can lift the back of their hand without moving the forearm.

Record any:

• wrist pain

• forearm pain

• hand pain

• previous wrist injury

• previous surgery

• neurological symptoms

• fatigue

Complete one or two familiarisation contractions before maximal testing.

2. Position the client

Position the client:

• seated upright

• forearm fully supported

• elbow flexed to approximately 90°

• forearm pronated

• wrist in neutral

• fingers relaxed

Maintain identical positioning during every reassessment.

3. Position the testing limb

Ensure:

• the forearm remains supported

• the elbow remains still

• the wrist begins in neutral

• the hand remains relaxed

Position the Anker load cell against the dorsal surface of the second and third metacarpals, immediately proximal to the metacarpal heads.

Avoid direct pressure over the fingers or wrist joint.

Record the contact point to improve repeatability.

4. Stabilise the client

Prevent movement of:

• forearm

• elbow

• shoulder

• trunk

The movement should occur only as an isometric wrist extension effort.

5. Testing instructions

Use consistent verbal cues.

"Lift the back of your hand."

"Increase the pressure smoothly."

"Push as hard as you can."

"Hold."

"Keep breathing."

Repeat the same wording during every reassessment.

6. Record the assessment

Use:

• 1–2 familiarisation trials

• 2–3 maximal trials

• 3–5 second contractions

• 30–60 seconds rest between trials

Record either:

• the highest force value, or

• the average of the recorded trials

Maintain the same scoring method during future testing.

7. Repeat the trial if

• the forearm lifts

• the elbow moves

• the shoulder compensates

• the wrist deviates

• the fingers extend excessively

• the load cell slips

• pain limits maximal effort

• the client starts before instructed

Why It Is Used

The assessment may be useful for:

• establishing baseline wrist extensor strength

• comparing left and right limbs

• monitoring changes over time

• upper-limb strength profiling

• athlete performance assessment

• objective reporting using Measurz

• monitoring response to exercise

• client education

The assessment should contribute to broader assessment reasoning and should not be used as a stand-alone diagnostic assessment.

What It Measures

The primary outcome is peak isometric wrist extension 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:

• wrist range of motion

• ligament integrity

• tendon pathology

• grip endurance

• readiness for work or sport

Understanding the Result, Reference Values and What to Look For

Higher force values generally indicate greater wrist extensor strength.

Lower force values may reflect:

• pain

• fatigue

• previous injury

• reduced confidence

• inconsistent positioning

• movement compensation

Interpret results by considering:

• previous assessment results

• left versus right differences

• symptoms during testing

• grip strength

• occupational and sporting demands

Published Anker-specific normative values are currently unavailable.

Handheld dynamometry has demonstrated good reliability for wrist extensor testing when forearm position, wrist position and lever arm remain standardised. Comparing results with the client's own baseline and repeated testing using the same protocol provides the most meaningful assessment of change.

A side-to-side difference of approximately 10% or greater may warrant further assessment when accompanied by symptoms or functional limitations.

Assessing Different Client Populations

Youth

Interpret relative to growth, coordination and sporting participation.

Adults

Useful for baseline assessment and monitoring progress.

Older adults

Interpret alongside grip strength, hand function and activities of daily living.

Athletes

Particularly useful for racquet sports, climbing, golf, baseball, cricket and manual workers.

Clients with persistent symptoms

Interpret alongside pain, confidence and functional performance rather than strength alone.

Common Errors and Limitations

Common errors include:

• forearm lifting

• elbow movement

• wrist deviation

• finger extension

• inconsistent load cell placement

• inconsistent verbal cueing

Limitations include:

• results are position-specific

• pain may reduce maximal force production

• muscle strength alone does not determine upper-limb function

• published Anker-specific normative values remain limited

Practical Applications

The assessment may be useful for:

• baseline assessment

• progress monitoring

• side-to-side comparison

• upper-limb performance profiling

• objective reporting within Measurz

• educating clients using measurable outcomes

FAQs

What does the Wrist Extension Strength Test measure?

It measures maximal isometric wrist extension strength.

Which muscles are primarily assessed?

Extensor carpi radialis longus, extensor carpi radialis brevis and extensor carpi ulnaris.

Which metric should be used routinely?

Peak force is the primary outcome measure.

Should both wrists be tested?

Yes. Bilateral testing allows meaningful comparison.

Can this assessment diagnose wrist pathology?

No. It measures muscle force only.

Key Takeaways

• Measures maximal isometric wrist extension strength.

• Primarily assesses the wrist extensor muscles.

• Peak force is the primary routine outcome measure.

• Consistent positioning and metacarpal contact point improve repeatability.

• Measurz provides additional force-time metrics.

• Compare results with previous assessments and the opposite limb.

References

Bohannon, R. W. (1997). Reference values for extremity muscle strength obtained by hand-held dynamometry from adults aged 20 to 79 years. Archives of Physical Medicine and Rehabilitation, 78(1), 26–32.

Stark, T., Walker, B., Phillips, J. K., Fejer, R., & Beck, R. (2011). Hand-held dynamometry correlation with the gold standard isokinetic dynamometry: A systematic review. PM&R, 3(5), 472–479.

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.