Anker: Forearm Pronation Strength Test

The Forearm Pronation Strength Test measures the maximum isometric force produced when the forearm rotates so the palm faces downward. Using the Anker, the assessment provides an objective and repeatable measure of forearm pronation strength in a standardised position.

Pronation strength contributes to gripping, manual handling, tool use, lifting, throwing, racquet sports, climbing and many occupational tasks requiring forearm control. Assessing pronation complements supination testing and provides a more complete profile of forearm rotational strength.

The primary muscles assessed are the pronator teres and pronator quadratus, with assistance from the flexor carpi radialis during stabilisation.

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, elbow and wrist mobility, grip strength and functional performance.

What Is the Forearm Pronation Strength Test?

The Forearm Pronation Strength Test is an isometric assessment where the client attempts to rotate the forearm so the palm turns downward while maintaining a stable elbow and upper arm.

The assessment is commonly performed with the elbow flexed to 90° and the shoulder positioned against the trunk to minimise compensation and improve repeatability.

The Anker provides fixed resistance, allowing consistent testing when positioning, anatomical landmarks and instructions remain unchanged.

Step-by-Step Protocol

1. Prepare the client

Explain that the assessment measures how strongly they can rotate their palm downwards without moving the elbow or shoulder.

Record any:

• elbow pain

• forearm pain

• wrist pain

• previous upper-limb injury

• previous surgery

• neurological symptoms

• fatigue

Complete one or two familiarisation contractions before maximal testing.

2. Position the client

Position the client:

• seated upright

• feet flat on the floor

• trunk supported

• shoulder adducted against the trunk

• elbow flexed to 90°

• forearm in neutral rotation

• wrist neutral

Maintain the same positioning during every reassessment.

3. Position the testing limb

Ensure:

• the upper arm remains against the trunk

• the elbow stays flexed to 90°

• the wrist remains neutral

• the hand remains relaxed

Position the Anker load cell against the dorsal surface of the distal forearm, immediately proximal to the radial and ulnar styloid processes.

Avoid placing the load cell directly over the wrist joint.

Record the contact point for consistent retesting.

4. Stabilise the client

Prevent movement of:

• trunk

• shoulder

• upper arm

• elbow

The movement should occur only as an isometric forearm pronation effort.

5. Testing instructions

Use consistent verbal cues.

"Turn your palm down."

"Increase the pressure smoothly."

"Push as hard as you can."

"Hold."

"Keep breathing."

Use identical instructions 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 recorded trials

Maintain the same scoring method during future testing.

7. Repeat the trial if

• the elbow moves

• the shoulder rotates

• the trunk leans

• the wrist flexes or extends

• 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 forearm 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 support broader assessment reasoning and should not be used as a stand-alone diagnostic or clearance assessment.

What It Measures

The primary outcome is peak isometric forearm pronation 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:

• elbow stability

• tendon integrity

• range of motion

• hand dexterity

• grip endurance

• readiness for work or sport

Understanding the Result, Reference Values and What to Look For

Higher force values generally indicate greater forearm pronation strength.

Lower force values may reflect:

• pain

• fatigue

• previous injury

• reduced effort

• 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.

Forearm rotational dynamometry demonstrates good repeatability when elbow position, forearm position and stabilisation remain consistent. Because testing methods differ between devices, baseline comparison and repeated testing using identical protocols provide the most clinically useful information.

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

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 upper-limb function and daily activities.

Athletes

Particularly useful for racquet sports, climbing, baseball, cricket, golf and strength athletes.

Clients with persistent symptoms

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

Common Errors and Limitations

Common errors include:

• shoulder rotation

• elbow movement

• wrist flexion or extension

• excessive gripping

• 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 function

• published Anker-specific normative values remain limited

Practical Applications

The assessment may be useful for:

• establishing baseline forearm strength

• monitoring progress

• side-to-side comparison

• upper-limb performance profiling

• objective reporting within Measurz

• educating clients using measurable outcomes

FAQs

What does the Forearm Pronation Strength Test measure?

It measures maximal isometric forearm pronation strength.

Which muscles are primarily assessed?

The pronator teres and pronator quadratus.

Which metric should be used routinely?

Peak force is the primary outcome measure.

Should both forearms be tested?

Yes. Bilateral testing provides meaningful comparison.

Can this assessment diagnose elbow pathology?

No. It measures muscle force only and should always be interpreted alongside other assessment findings.

Key Takeaways

• Measures maximal isometric forearm pronation strength.

• Primarily assesses the pronator teres and pronator quadratus.

• Peak force is the primary routine outcome measure.

• Consistent positioning and forearm 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.