The Shoulder Abduction Strength Test measures the maximum isometric force produced as the arm moves away from the side of the body in the frontal plane. Using the Anker, the assessment provides an objective and repeatable measure of shoulder abductor strength in a standardised position.
Shoulder abduction strength is essential for overhead reaching, lifting, carrying, throwing, racquet sports and many occupational tasks. It also contributes to glenohumeral stability by maintaining appropriate humeral head positioning during arm elevation.
The primary muscles assessed include the middle deltoid and supraspinatus, with assistance from the upper trapezius and serratus anterior to stabilise the scapula.
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.
The Shoulder Abduction Strength Test is an isometric assessment where the client attempts to lift the arm away from the body while maintaining a stable shoulder girdle and trunk.
The assessment is commonly performed with the shoulder abducted to approximately 90° in the scapular plane, where the glenohumeral joint is positioned comfortably while allowing consistent force production.
The fixed resistance provided by the Anker enables repeatable testing when the same client position, anatomical landmarks and verbal instructions are maintained.
Explain that the assessment measures how strongly they can lift their arm out to the side.
Record any:
shoulder pain
upper arm pain
neck pain
previous shoulder injury
previous surgery
neurological symptoms
fatigue
Perform one or two familiarisation contractions before maximal testing.
Position the client:
seated upright
feet flat on the floor
trunk supported
shoulder abducted to approximately 90° in the scapular plane
elbow extended or comfortably flexed according to the Anker setup
thumb pointing upwards if using the scapular plane
Maintain identical positioning during every reassessment.
Ensure:
the scapula remains neutral
the humerus remains aligned in the scapular plane
the elbow remains stable
the wrist remains relaxed
Position the Anker load cell against the lateral aspect of the distal humerus, approximately 5 cm proximal to the lateral epicondyle.
Avoid direct contact over the elbow joint.
Record the contact point for consistent retesting.
Prevent movement of:
trunk
pelvis
opposite shoulder
excessive scapular elevation
The effort should occur through shoulder abduction rather than trunk side flexion.
Use consistent verbal instructions.
"Lift your arm out to the side."
"Increase the pressure smoothly."
"Push as hard as you can."
"Hold."
"Keep breathing."
Repeat the same wording during every reassessment.
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 for future assessments.
the trunk leans
the shoulder elevates
the elbow changes position
the scapula excessively elevates
the load cell slips
pain limits maximal effort
the client starts before instructed
The assessment may be useful for:
establishing baseline shoulder strength
comparing left and right limbs
monitoring strength 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 clearance assessment.
The primary outcome is peak isometric shoulder abduction 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:
rotator cuff integrity
shoulder stability
shoulder mobility
movement quality
overhead performance
readiness for work or sport
Higher force values generally indicate greater shoulder abduction 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
movement compensations
occupational, sporting and daily-life demands
Published Anker-specific normative values are currently unavailable.
Shoulder abduction dynamometry has demonstrated excellent repeatability when testing position, lever arm and stabilisation are standardised. Repeated testing using the same protocol provides more meaningful information than comparison with external reference values.
A side-to-side difference of approximately 10% or greater may warrant further assessment when consistent with symptoms or reduced function.
Youth
Interpret relative to growth, coordination and sporting participation.
Adults
Useful for baseline assessment and monitoring progress.
Older adults
Interpret alongside reaching ability, lifting tasks and daily activities.
Athletes
Particularly useful for overhead athletes, swimmers, climbers, volleyball players, tennis players and strength athletes.
Clients with persistent symptoms
Interpret alongside pain, confidence and functional capacity rather than strength alone.
Common errors include:
trunk leaning
shoulder elevation
scapular shrugging
elbow movement
inconsistent load cell placement
inconsistent verbal cueing
Limitations include:
results are specific to the testing position
pain may reduce maximal force production
muscle strength alone does not determine shoulder function
published Anker-specific normative values remain limited
The assessment may be useful for:
establishing baseline shoulder strength
monitoring progress
side-to-side comparison
athlete profiling
objective reporting within Measurz
educating clients using measurable outcomes
It measures maximal isometric shoulder abduction strength.
Testing in the scapular plane places the shoulder in a comfortable position that is often better tolerated while maintaining good repeatability.
Peak force is the primary outcome measure.
Yes. Bilateral testing allows meaningful comparison.
No. It measures muscle force only and should always be interpreted alongside other assessment findings.
Measures maximal isometric shoulder abduction strength.
Primarily assesses the middle deltoid and supraspinatus.
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.
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.
