The Hip Internal Rotation Strength Test measures the maximum isometric force produced during hip internal rotation with the hip positioned in neutral (0° hip flexion). Performed using the Anker, the assessment provides an objective measure of hip internal rotator strength in a standardised and repeatable position.
Assessing hip rotation strength in neutral complements testing performed at 90° of hip flexion, as muscle contribution and force production vary with hip position. The assessment may assist with baseline strength profiling, side-to-side comparison and monitoring changes over time.
The primary muscles contributing to hip internal rotation include the anterior fibres of gluteus medius, anterior gluteus minimus and tensor fasciae latae, while several adductor muscles provide secondary assistance depending on hip position.
When used with Measurz, the Anker records peak force and can calculate additional force-time 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 strength only and should always be interpreted alongside symptoms, movement quality and functional performance.
The Hip Internal Rotation Strength Test is an isometric assessment performed with the hip in a neutral position (0° flexion). The client attempts to rotate the leg inward by pushing the lower leg against the Anker while maintaining a stable pelvis and trunk.
Unlike testing at 90° hip flexion, assessing internal rotation in neutral places the hip musculature in a different mechanical position and may provide additional information about hip strength across functional positions.
The Anker's fixed resistance and four independent load cells allow the assessment to be reproduced consistently when the same setup is used during every testing session.
Explain that the assessment measures how strongly they can rotate their leg inward without allowing the hip or trunk to move.
Record any:
hip pain
groin pain
buttock pain
lower back pain
recent injury
previous surgery
neurological symptoms
fatigue
Perform one or two submaximal practice contractions before maximal testing.
Position the client in long sitting or supine, depending on the Anker configuration.
Maintain:
hips in neutral (0° flexion)
knees fully extended unless the protocol specifies otherwise
pelvis level
trunk supported
lower limbs aligned with the pelvis
feet pointing towards the ceiling
The same position should be reproduced during every reassessment.
Ensure:
the patella faces directly upwards
the femur remains in neutral rotation before testing
the tibia remains aligned with the femur
the ankle remains relaxed
Position the Anker load cell against the lateral aspect of the distal tibia, approximately 2–3 cm superior to the lateral malleolus.
Avoid contact directly over the lateral malleolus or fibular head.
Record the contact point to ensure identical positioning during future assessments.
Prevent movement of:
pelvis
lumbar spine
opposite limb
trunk
The movement should be generated by the hip only.
Use consistent verbal instructions.
"Push your leg outwards."
"Build the pressure gradually."
"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 contraction
30–60 seconds recovery between trials
Record either:
the highest value, or
the average of the recorded trials
Use the same scoring method during every reassessment.
the pelvis rotates
the lumbar spine moves
the opposite leg assists
the testing leg lifts
the load cell slips
pain limits maximal effort
the client begins before instructed
The Hip Internal Rotation Strength Test may be useful for:
establishing baseline hip strength
comparing left and right limbs
monitoring changes following injury or reduced loading
lower-limb strength profiling
athlete performance assessment
monitoring exercise progress
objective reporting using Measurz
educating clients about measurable change
The assessment should contribute to a broader assessment process and should not be used in isolation.
The primary outcome is peak isometric hip internal rotation force with the hip positioned in neutral.
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:
hip joint mobility
structural pathology
balance
movement quality
running mechanics
readiness to return to sport
Higher force values generally indicate greater hip internal rotation strength in the tested position.
Lower force values may reflect:
pain
reduced confidence
fatigue
previous injury
poor familiarisation
inconsistent positioning
movement compensation
When interpreting results:
compare with previous assessments
compare left and right limbs
consider symptoms during testing
observe compensatory movement
relate findings to the client's functional goals
Published Anker-specific normative values are currently unavailable.
Research has consistently demonstrated excellent reliability for hip strength assessment using fixed and handheld dynamometry when standardised protocols are followed. Healthy adults generally demonstrate less than a 10% side-to-side difference in hip rotational strength, although acceptable variation depends on the individual's sporting background, previous injury and testing methodology.
Comparing results with the client's own baseline and using consistent testing procedures is generally more valuable than comparing absolute force values between different dynamometry systems.
Youth
Provide additional familiarisation trials and interpret findings relative to growth, maturation and activity level.
Adults
Useful for baseline assessment and long-term monitoring.
Older adults
Interpret alongside mobility, balance, transfers and daily function.
Athletes
Useful for assessing rotational hip strength as part of a comprehensive lower-limb performance profile.
Clients with persistent symptoms
Interpret results alongside pain, confidence and movement quality rather than strength alone.
Common errors include:
pelvis rotating
lumbar extension
opposite leg assisting
inconsistent load cell placement
inconsistent starting position
excessive trunk movement
inconsistent verbal cueing
Limitations include:
results are specific to the testing position
pain may reduce force production
muscle strength alone does not determine functional performance
published Anker-specific normative data remain limited
The assessment may be useful for:
establishing baseline hip strength
monitoring progress over time
comparing left and right limbs
lower-limb performance profiling
objective reporting using Measurz
educating clients using measurable outcomes
It measures maximal isometric hip internal rotation strength with the hip positioned in neutral (0° flexion).
Hip muscle contribution changes with hip position. Assessing both positions may provide a more comprehensive understanding of hip rotational strength.
Peak force is the primary outcome measure for routine assessment.
Yes. Bilateral testing provides meaningful side-to-side comparison and assists with progress monitoring.
No. It measures muscle strength only and should always be interpreted alongside other assessment findings.
Measures maximal isometric hip internal rotation strength with the hip in neutral.
Complements hip rotation testing performed at 90° of hip flexion.
Peak force is the primary outcome measure.
Standardised positioning improves repeatability.
Measurz provides additional force-time metrics.
Baseline comparison and consistent retesting are generally more valuable than published reference values.
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.
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.
Thorborg, K., Bandholm, T., Schick, M., Jensen, J., & Hölmich, P. (2013). Hip strength assessment using handheld dynamometry is reliable in athletes. Scandinavian Journal of Medicine & Science in Sports, 23(3), e181–e189.
