Anker: Shoulder Adduction Strength Test

The Shoulder Adduction Strength Test measures the maximum isometric force produced as the arm is drawn towards the side of the body. Using the Anker, the assessment provides an objective and repeatable measure of shoulder adductor strength in a standardised position.

Shoulder adduction is an important movement during climbing, swimming, rowing, gymnastics, lifting, pulling and many occupational tasks requiring upper-limb force. The assessment is useful for baseline strength profiling, side-to-side comparison and monitoring changes over time.

The primary muscles assessed include the latissimus dorsi, pectoralis major, teres major and coracobrachialis, with assistance from the long head of the triceps brachii depending on shoulder position.

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, shoulder mobility and functional performance.

What Is the Shoulder Adduction Strength Test?

The Shoulder Adduction Strength Test is an isometric assessment where the client attempts to pull the arm towards the body while maintaining a stable shoulder girdle and trunk.

The assessment is commonly performed with the shoulder abducted to approximately 90° and the elbow extended or comfortably flexed, depending on the Anker configuration. The objective is to isolate shoulder adduction while minimising compensation from the trunk or scapula.

The fixed resistance provided by the Anker allows consistent testing when the same client position, anatomical landmarks and verbal instructions are reproduced at every assessment.

Step-by-Step Protocol

1. Prepare the client

Explain that the assessment measures how strongly they can pull their arm down towards their side.

Record any:

• shoulder pain

• upper arm pain

• neck pain

• previous shoulder injury

• previous surgery

• neurological symptoms

• fatigue

Perform one or two submaximal familiarisation contractions before maximal testing.

2. Position the client

Position the client:

• seated upright

• feet flat on the floor

• trunk supported

• shoulder abducted to approximately 90°

• elbow comfortably extended or slightly flexed

• forearm in neutral rotation

Maintain identical positioning during every reassessment.

3. Position the testing limb

Ensure:

• the scapula remains neutral

• the humerus remains level with the shoulder

• the elbow remains aligned with the shoulder

• the wrist remains relaxed

Position the Anker load cell against the medial aspect of the distal humerus, approximately 5 cm proximal to the medial epicondyle.

Avoid direct contact over the elbow joint.

Record the contact point to improve repeatability.

4. Stabilise the client

Prevent movement of:

• trunk

• pelvis

• opposite shoulder

• scapular elevation

The effort should occur through shoulder adduction rather than trunk side flexion or rotation.

5. Testing instructions

Use consistent verbal instructions.

"Pull your arm towards your side."

"Increase the pressure smoothly."

"Push as hard as you can."

"Hold."

"Keep breathing."

Use the same 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 the recorded trials

Maintain the same scoring method during future assessments.

7. Repeat the trial if

• the trunk leans

• the trunk rotates

• the shoulder elevates

• the elbow changes position

• 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 shoulder strength

• comparing left and right limbs

• monitoring changes over time

• athlete performance profiling

• 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 return-to-sport assessment.

What It Measures

The primary outcome is peak isometric shoulder adduction 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:

• shoulder mobility

• rotator cuff integrity

• shoulder stability

• movement quality

• sporting performance

• readiness for work or sport

Understanding the Result, Reference Values and What to Look For

Higher force values generally indicate greater shoulder adduction strength.

Lower force values may reflect:

• pain

• fatigue

• previous injury

• reduced effort

• inconsistent positioning

• movement compensation

Interpret results by considering:

• previous assessments

• left versus right comparison

• symptoms during testing

• movement compensations

• functional demands

Published Anker-specific normative values are currently unavailable.

Shoulder dynamometry studies demonstrate excellent repeatability when testing position, stabilisation and lever arm remain consistent. Because force values vary between testing systems, comparison with the client's own baseline and repeated assessments using the same protocol are generally more meaningful than comparison with published values.

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 upper-limb function and daily activities.

Athletes

Particularly useful for swimmers, climbers, rowers, gymnasts, rugby players 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:

• trunk leaning

• trunk rotation

• shoulder elevation

• elbow movement

• inconsistent load cell placement

• inconsistent verbal cueing

Limitations include:

• results are position-specific

• pain may reduce maximal force production

• strength alone does not determine function

• published Anker-specific normative values remain limited

Practical Applications

The assessment may be useful for:

• baseline shoulder assessment

• monitoring progress

• side-to-side comparison

• athlete profiling

• objective reporting within Measurz

• educating clients using measurable outcomes

FAQs

What does the Shoulder Adduction Strength Test measure?

It measures maximal isometric shoulder adduction strength.

Which muscles are primarily assessed?

Latissimus dorsi, pectoralis major, teres major and coracobrachialis.

Which metric should be used routinely?

Peak force is the primary outcome measure.

Should both shoulders be tested?

Yes. Bilateral testing allows meaningful side-to-side comparison.

Can this assessment diagnose shoulder pathology?

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

Key Takeaways

• Measures maximal isometric shoulder adduction strength.

• Primarily assesses the latissimus dorsi, pectoralis major and teres major.

• Peak force is the primary routine outcome measure.

• Consistent positioning and load cell placement improve repeatability.

• Measurz provides additional force-time metrics.

• Compare results with previous assessments and the opposite shoulder.

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.