The Forearm Supination Strength Test measures the maximum isometric force produced when the forearm rotates so the palm faces upward. Using the Anker, the assessment provides an objective and repeatable measure of forearm supination strength in a standardised position.
Supination strength is important for gripping, lifting, carrying, using tools, opening doors, racquet sports, climbing and many occupational tasks. It also contributes to efficient hand positioning during activities requiring precision and force generation.
The primary muscles assessed are the biceps brachii and supinator, with assistance from the brachioradialis when moving towards a neutral forearm 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, elbow and wrist mobility, grip strength and functional performance.
The Forearm Supination Strength Test is an isometric assessment where the client attempts to rotate the forearm so the palm turns upwards while maintaining a stable elbow and upper arm.
The assessment is commonly performed with the elbow flexed to 90° and the upper arm positioned against the trunk. This position reduces compensation from the shoulder while allowing consistent loading of the supinator muscles.
The Anker provides fixed resistance, allowing repeatable testing when client positioning, anatomical landmarks and verbal instructions remain consistent.
Explain that the assessment measures how strongly they can rotate their palm upwards without moving the elbow or shoulder.
Record any:
elbow pain
forearm pain
wrist pain
previous upper-limb 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 adducted against the side
elbow flexed to 90°
forearm in neutral rotation
wrist maintained in a neutral position
Maintain identical positioning during every reassessment.
Ensure:
the humerus 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 palmar surface of the distal forearm, immediately proximal to the radial and ulnar styloid processes.
Avoid positioning directly over the wrist joint or hand.
Record the contact point to improve repeatability.
Prevent movement of:
trunk
shoulder
upper arm
elbow
The movement should occur only as an isometric forearm supination effort.
Use consistent verbal cues.
"Turn your palm upwards."
"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 during future testing.
the elbow moves
the shoulder rotates
the trunk leans
the wrist flexes or extends excessively
the load cell slips
pain limits maximal effort
the client starts before instructed
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 contribute to a broader physical assessment and should not be used as a stand-alone diagnostic or clearance test.
The primary outcome is peak isometric forearm supination 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 joint stability
tendon integrity
forearm range of motion
grip endurance
hand dexterity
readiness for work or sport
Higher force values generally indicate greater forearm supination 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
functional demands
Published Anker-specific normative values are currently unavailable.
Forearm rotational strength has demonstrated good reliability using handheld dynamometry when elbow position, forearm position and stabilisation are standardised. Because force values differ between devices and testing methods, comparison with the client's own baseline and repeated testing using the same protocol are generally more meaningful than external normative values.
A side-to-side difference of approximately 10% or greater may warrant further investigation when accompanied by symptoms or functional limitations.
Youth
Interpret relative to growth, coordination and sporting participation.
Adults
Useful for baseline assessment and monitoring strength over time.
Older adults
Interpret alongside grip strength, lifting ability and daily activities.
Athletes
Particularly useful for racquet sports, climbing, throwing sports, gymnastics and strength athletes.
Clients with persistent symptoms
Interpret alongside pain, confidence and functional capacity rather than strength alone.
Common errors include:
shoulder rotation
elbow movement
wrist flexion or extension
gripping excessively during the test
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 upper-limb function
published Anker-specific normative values remain limited
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
It measures maximal isometric forearm supination strength.
The biceps brachii and supinator.
Peak force is the primary outcome measure.
Yes. Bilateral testing provides meaningful side-to-side comparison.
No. It measures muscle force only and should always be interpreted alongside other assessment findings.
Measures maximal isometric forearm supination strength.
Primarily assesses the biceps brachii and supinator.
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.
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.
