The Wrist Radial Deviation Strength Test measures the maximum isometric force produced when the wrist moves towards the thumb side of the forearm. Using the Anker, the assessment provides an objective and repeatable measure of wrist radial deviator strength in a standardised testing position.
Radial deviation contributes to grip stability, lifting, carrying, racquet sports, golf, baseball, climbing, manual handling and many occupational tasks requiring controlled wrist positioning. It also assists with stabilising the wrist during gripping activities by balancing the action of the wrist flexors and extensors.
The primary muscles assessed include extensor carpi radialis longus, extensor carpi radialis brevis and flexor carpi radialis.
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, wrist mobility, grip strength and functional performance.
The Wrist Radial Deviation Strength Test is an isometric assessment where the client attempts to move the hand towards the thumb side while maintaining a stable forearm and elbow.
The assessment is typically performed with the forearm resting comfortably, the elbow flexed to approximately 90° and the wrist beginning in a neutral position. Standardising forearm position reduces compensatory movement and improves repeatability.
The fixed resistance provided by the Anker allows the assessment to be reproduced consistently when positioning, anatomical landmarks and verbal instructions remain unchanged.
Explain that the assessment measures how strongly they can move their hand towards the thumb side without moving their forearm.
Record any:
wrist pain
thumb pain
forearm pain
previous wrist injury
previous surgery
neurological symptoms
fatigue
Complete one or two familiarisation contractions before maximal testing.
Position the client:
seated upright
forearm fully supported
elbow flexed to approximately 90°
forearm in neutral rotation
wrist in neutral
fingers relaxed
Maintain identical positioning during every reassessment.
Ensure:
the forearm remains supported
the elbow remains still
the wrist begins in neutral
the hand remains relaxed
Position the Anker load cell against the radial border of the second metacarpal, just proximal to the metacarpal head.
Avoid direct pressure over the thumb or wrist joint.
Record the contact point for future testing.
Prevent movement of:
forearm
elbow
shoulder
trunk
The movement should occur only as an isometric wrist radial deviation effort.
Use consistent verbal cues.
"Move your hand towards your thumb."
"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 assessments.
the forearm lifts
the elbow moves
the shoulder compensates
the wrist flexes or extends
the load cell slips
pain limits maximal effort
the client starts before instructed
The assessment may be useful for:
establishing baseline wrist strength
comparing left and right limbs
monitoring strength 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 assessment.
The primary outcome is peak isometric wrist radial deviation 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:
wrist joint stability
ligament integrity
wrist range of motion
grip endurance
hand dexterity
readiness for work or sport
Higher force values generally indicate greater radial deviation strength.
Lower force values may reflect:
pain
fatigue
previous injury
reduced confidence
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.
Handheld dynamometry has demonstrated good reliability for wrist strength assessment when forearm position, wrist position and lever arm are standardised. Because testing protocols vary between devices, comparison with the client's own baseline and repeated assessments using the same protocol are generally more meaningful than comparison with published force values.
A side-to-side difference of approximately 10% or greater may warrant further assessment when accompanied by symptoms or functional limitations.
Youth
Interpret relative to growth, coordination and sporting participation.
Adults
Useful for baseline assessment and monitoring progress.
Older adults
Interpret alongside grip strength, hand function and activities of daily living.
Athletes
Particularly useful for racquet sports, golf, climbing, baseball, cricket and strength athletes.
Clients with persistent symptoms
Interpret alongside pain, confidence and functional capacity rather than strength alone.
Common errors include:
forearm lifting
elbow movement
wrist flexion or extension
excessive finger 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 upper-limb function
published Anker-specific normative values remain limited
The assessment may be useful for:
establishing baseline wrist strength
monitoring progress
side-to-side comparison
upper-limb performance profiling
objective reporting within Measurz
educating clients using measurable outcomes
It measures maximal isometric wrist radial deviation strength.
Extensor carpi radialis longus, extensor carpi radialis brevis and flexor carpi radialis.
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 wrist radial deviation strength.
Primarily assesses the radial wrist deviators.
Peak force is the primary routine outcome measure.
Consistent positioning and metacarpal 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.
