The Shoulder External Rotation Strength Test measures the maximum isometric force produced during shoulder external rotation with the shoulder positioned at 0° of abduction. Using the Anker, the assessment provides an objective and repeatable measure of shoulder external rotator strength in a standardised position.
The shoulder external rotators play a critical role in glenohumeral stability by controlling humeral head position during arm movement. They are heavily involved in throwing deceleration, overhead sports, rowing, swimming and posture, making this assessment valuable for both athletic performance profiling and upper-limb strength monitoring.
The primary muscles assessed include the infraspinatus and teres minor, with assistance from the posterior deltoid depending on shoulder position.
When used with Measurz, the Anker records peak force and can calculate 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 External Rotation Strength Test is an isometric assessment where the client attempts to rotate the forearm away from the body while the elbow remains flexed to 90° and the upper arm stays against the trunk.
Testing at 0° shoulder abduction provides a stable and repeatable position that is commonly used when assessing rotator cuff strength. This position reduces compensatory movement and allows consistent assessment across repeated testing sessions.
The Anker's fixed resistance allows objective strength measurement when positioning, anatomical landmarks and instructions remain consistent.
Explain that the assessment measures how strongly they can rotate their forearm away from their body without moving their elbow.
Record any:
shoulder pain
neck pain
previous shoulder injury
previous surgery
neurological symptoms
stiffness
fatigue
Complete one or two familiarisation contractions before maximal testing.
Position the client:
seated upright
feet flat on the floor
trunk supported
shoulder adducted against the side of the body
elbow flexed to 90°
forearm in neutral rotation
A towel between the arm and trunk may improve consistency by maintaining the shoulder in a neutral position.
Use the same setup during every reassessment.
Ensure:
the humerus remains against the trunk
the elbow remains flexed to 90°
the forearm begins in neutral
the wrist remains relaxed
Position the Anker load cell against the dorsal (posterior) aspect of the distal forearm, approximately 3–5 cm proximal to the radial and ulnar styloid processes.
Avoid positioning directly over the wrist joint.
Record the contact point for future testing.
Prevent movement of:
trunk
shoulder girdle
scapula
elbow
The effort should come from shoulder external rotation only.
Use consistent verbal cues.
"Rotate your forearm away from your body."
"Increase the pressure smoothly."
"Push as hard as you can."
"Hold."
"Keep breathing."
Repeat the same instructions during every reassessment.
Use:
1–2 familiarisation trials
2–3 maximal trials
3–5 second contractions
30–60 seconds rest between trials
Record either:
highest force value, or
average of recorded trials
Maintain the same scoring method during future testing.
the elbow lifts away from the trunk
the shoulder abducts
the trunk rotates
the shoulder elevates
the load cell slips
pain limits maximal effort
the client starts before instructed
The assessment may be useful for:
baseline rotator cuff strength assessment
side-to-side comparison
athlete performance profiling
monitoring progress over time
objective reporting using Measurz
monitoring response to exercise
client education
The assessment should not be used as a stand-alone diagnostic or clearance assessment.
The primary outcome is peak isometric shoulder external rotation 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 instability
movement quality
shoulder mobility
overhead throwing mechanics
readiness for sport or work
Higher force values generally indicate greater shoulder external rotation strength.
Lower force values may reflect:
pain
fatigue
previous injury
reduced confidence
poor familiarisation
inconsistent positioning
movement compensation
Interpret results by considering:
previous assessment results
left versus right differences
symptoms during testing
movement compensations
occupational, sporting or daily-life demands
Published Anker-specific normative values are currently unavailable.
Shoulder external rotation strength has been extensively studied using handheld dynamometry and demonstrates excellent reliability when joint position, elbow position and stabilisation are standardised. As testing methods differ between devices, comparing results with the client's own baseline and repeated assessments using the same protocol is generally more meaningful than comparing absolute force values with external reference data.
A side-to-side difference of approximately 10% or greater may warrant further investigation when accompanied by symptoms, previous injury or functional limitations.
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 overhead sports, throwing athletes, swimmers, racquet sports and climbers.
Clients with persistent symptoms
Interpret alongside pain, confidence and functional performance rather than strength alone.
Common errors include:
elbow lifting from the trunk
shoulder abduction
trunk rotation
shoulder elevation
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 rotator cuff strength
monitoring progress
comparing left and right limbs
athlete profiling
objective reporting using Measurz
educating clients using measurable outcomes
It measures maximal isometric shoulder external rotation strength with the shoulder positioned at 0° abduction.
The external rotators are essential for shoulder stability and are frequently assessed in overhead athletes and individuals with shoulder symptoms.
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 external rotation strength.
Primarily assesses the infraspinatus and teres minor.
Peak force is the primary routine outcome measure.
Consistent positioning and forearm contact point improve repeatability.
Measurz provides additional force-time metrics.
Baseline comparison and repeated testing are generally more valuable than broad population norms.
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.
