The Prone Hip Internal Rotation Strength Test measures how much force a client can produce when rotating the thigh inward against resistance while lying face down. In the prone position, the hip is usually near neutral and the knee is commonly flexed to approximately 90 degrees, allowing the lower leg to move as the lever for hip rotation.
Hip internal rotation strength can provide useful context for walking, running, cutting, kicking, pivoting, change of direction, lower-limb alignment, hip rotation control and progress tracking. The main contributors include portions of gluteus medius and minimus, tensor fasciae latae, adductor group contributions and other muscles that assist femoral rotation or pelvis control.
The Muscle Meter is a handheld dynamometry tool used to measure force output during push, pull and isometric strength assessments. When used on its own, the Muscle Meter primarily measures peak force, which is the highest force value produced during the test. When used with Measurz, Muscle Meter data can be recorded and analysed with a broader set of strength and force-time metrics, including peak force, impulse, torque, rate of torque development, rate of force development, time to peak and fatigue index.
For routine prone hip internal rotation testing, peak force is usually the main metric. Force as a percentage of body weight may be useful if directly calculated from the client’s test force and body weight, especially for baseline comparison, side-to-side comparison and retesting. Rate of force development and time to peak may be useful when rapid hip rotation force matters, such as cutting, pivoting, kicking or sport-specific direction changes. Impulse may be useful if sustained internal rotation force over a defined time window is intentionally tested. Fatigue index is only relevant if repeated or sustained hip rotation efforts are part of the protocol.
The result can support assessment reasoning and progress tracking, but it does not diagnose hip impingement, labral injury, hip joint pathology, femoral version, groin pain, lower-back pain, knee pain or readiness for sport or work on its own.
The Prone Hip Internal Rotation Strength Test is an isometric lower-limb strength assessment where the client rotates the hip inward into the Muscle Meter, strap or fixed setup without visible movement. In a typical prone setup, the client lies face down with the knee bent, and the device is placed near the ankle or distal lower leg to resist the rotational force.
The movement direction is hip internal rotation. Because the client is prone, the lower leg often moves outward when the hip internally rotates. The purpose of the test is to measure how much rotational force the client can produce through the hip in a specific position.
Consistent setup matters because pelvis position, hip angle, knee angle, lower-leg position, device placement, contact point, strap angle and client effort can all affect the result. This test measures force output in a specific setup. It does not fully measure hip mobility, gait, running mechanics, cutting ability, pain source, dynamic control, endurance or sport/work readiness on its own.
Explain that the test measures how strongly they can rotate the hip inward while lying prone. Record baseline symptoms, hip discomfort, groin symptoms, lateral hip symptoms, lower-back symptoms, knee symptoms, fatigue, recent training or work exposure and confidence with maximal effort.
Use at least one submaximal practice trial so the client understands the direction of force. Many clients need practice because hip rotation can be confused with knee movement, ankle pushing or pelvis rotation.
Position the client prone with the hip near neutral and the knee flexed, commonly to approximately 90 degrees. The pelvis should remain level and stable on the table. The tested lower leg should be positioned so the client can rotate the hip internally without lifting the pelvis or shifting the trunk.
Record:
Prone position
Test side
Hip angle
Knee angle
Pelvis position
Trunk position
Lower-leg start position
Foot and ankle position
Device contact point
Whether a strap or fixed anchor was used
For a handheld setup, the professional holds the Muscle Meter against the distal lower leg or ankle region while the client rotates the hip inward. For stronger clients or improved repeatability, a strap-stabilised or fixed setup may be used.
If using a strap, record:
Anchor point
Strap angle
Strap length
Device position
Limb position
Whether any pre-tension was used
Whether the anchor moved during testing
Push, pull, handheld and strap-stabilised scores should be recorded separately unless the protocol supports direct comparison.
Place the Muscle Meter against the distal lower leg or ankle region, using a consistent contact point. Avoid uncomfortable pressure over bony or sensitive areas.
In prone testing, hip internal rotation usually creates an outward movement of the lower leg. The client should push into the device by rotating the hip rather than by moving the knee, ankle or pelvis.
Stabilise the pelvis and thigh so the client does not compensate with pelvic rotation, lumbar extension, trunk shifting, hip abduction, hip adduction, knee movement or ankle pushing.
The aim is controlled hip internal rotation force in the prone position.
Use consistent instructions such as:
“Rotate your hip inward by moving your lower leg outward into the device.”
“Build up smoothly, then push hard.”
“Keep your pelvis and trunk still.”
“Do not lift your hip or twist your body.”
“Keep breathing.”
“Tell me if you feel pain, cramping, tingling or anything unusual.”
Use the same wording at retest where possible.
Use 1–2 practice trials, then record 2–3 maximal trials. A common contraction duration is 3–5 seconds. Rest for 30–60 seconds between trials, or longer if symptoms, fatigue or cramping occur.
Record whether the final score uses the best trial or the average of recorded trials. Either approach may be used if it is applied consistently.
Repeat or mark a trial as invalid if:
The pelvis lifts or rotates
The trunk shifts
The hip moves out of the start position
The knee angle changes
The ankle pushes instead of the hip rotating
The device slips
The strap or anchor moves
Pain or cramping limits effort
The client starts before the device is ready
The client holds their breath excessively
The professional cannot hold the device steady
Record hip pain, groin symptoms, lower-back symptoms, lateral hip symptoms, knee symptoms, cramping, paraesthesia, confidence, apprehension and symptom response after testing. Do not repeatedly test through high pain, worsening symptoms or strong cramping.
For retesting, match the same position, device placement, strap setup, instructions, contraction duration, rest period, scoring method and symptom recording.
The Prone Hip Internal Rotation Strength Test is used to quantify hip internal rotator force output in a repeatable setup. It may be useful for:
Baseline hip rotation strength assessment
Side-to-side comparison
Monitoring change over time
Hip internal and external rotation strength profiling
Comparing prone and supine rotation findings where relevant
Supporting walking, running, cutting, kicking and pivoting assessment reasoning
Workplace context where turning, stepping, climbing or repeated lower-limb rotation tasks are relevant
Fitness and performance progress tracking
Client education
The test should support assessment reasoning. It should not be used as a stand-alone diagnostic or clearance measure.
The test primarily measures isometric hip internal rotation force output in the chosen prone setup. It reflects the client’s ability to produce inward femoral rotation force while controlling pelvis and trunk position.
It may provide useful information about:
Hip internal rotation force capacity
Side-to-side force difference
Internal-to-external rotation comparison
Confidence producing rotational hip force
Pain response during resisted internal rotation
Change in force over time
Relationship between strength and related movement tasks
It does not directly measure:
Hip joint structure
Femoral version
Cause of hip or groin pain
Labral integrity
Lower-back pain source
Knee pain source
Running mechanics
Cutting ability
Readiness to return to sport or work
A higher score may suggest greater hip internal rotation force output in that specific prone test setup. A lower score may suggest reduced internal rotation force output, but the reason should be interpreted carefully.
Lower force may be influenced by pain, apprehension, poor familiarisation, fatigue, guarding, inconsistent device placement, poor pelvis stabilisation, reduced confidence, hip symptoms, lower-back symptoms, knee symptoms or compensation from the ankle or trunk.
One result should not be interpreted in isolation. Interpretation is strongest when the same setup is repeated over time and reviewed alongside symptoms, confidence, hip rotation range of motion, external rotation strength, single-leg tasks, gait, running exposure, kicking, cutting or work-specific demands.
Important influences include:
Pain
Apprehension
Poor familiarisation
Fatigue
Guarding
Poor pelvis or trunk stabilisation
Pelvis rotation
Lower-back extension
Different hip angle
Different knee angle
Different lower-leg position
Different device placement
Different strap angle
Ankle pushing instead of hip rotation
Breath holding
Client confidence
Professional strength if using handheld resistance
Published Muscle Meter-specific universal norms for prone hip internal rotation are limited. Reference values should therefore be used as context only and not as direct targets unless the protocol is closely matched.
More user-friendly comparison data include:
In a sample of 52 women aged 20–29 years, hip internal rotator force measured with handheld dynamometry was reported at approximately 23.82% of body weight. This means a 70 kg person in a similar setup would produce roughly 17 kg of force, but this should only be used as broad context unless the protocol is closely matched.
The original prone hip internal rotation article reports average isometric hip internal rotation force of approximately 49 N for men and 35 N for women in healthy young adults aged 18–30 years. In practical terms, 49 N is roughly similar to 5 kg of force, while 35 N is roughly similar to 3.5 kg of force.
Hip rotation force can change depending on hip position. Research comparing hip rotation at different hip flexion angles shows that position matters, so prone, seated and supine values should not be treated as interchangeable.
For side-to-side comparison, a difference of around 10% or more is often worth reviewing more closely, especially if it matches symptoms, previous injury, confidence changes or functional differences. This is not a strict pass/fail cut-off.
Comparing internal rotation with external rotation can also be useful. Large differences between directions may provide context, especially when paired with symptoms, hip range of motion, running, kicking, pivoting, cutting or work demands.
If force is recorded as a percentage of body weight in Measurz, use it mainly for the client’s own baseline, side-to-side comparison and retesting. Bodyweight percentage is useful only when calculated from the client’s actual test force and body weight.
These values are best used as comparison data. They can help provide context, but they should not be used as diagnostic, clearance or pass/fail cut-offs.
Use this order:
Compare with the client’s own baseline.
Compare right and left sides when relevant.
Compare internal and external rotation where relevant.
Review force relative to body weight where calculated.
Consider symptoms during and after testing.
Consider confidence and effort quality.
Review whether compensations were present.
Compare with related strength, mobility or performance tests.
Relate the result to walking, running, kicking, cutting, sport, work or daily-life demands.
Retest under the same conditions to monitor change.
Do not use reference values as pass/fail criteria.
Peak force
Use for maximum hip internal rotation force output, baseline strength, side-to-side comparison, internal-to-external rotation comparison, progress tracking and comparing force across retests. Look for best score or average score, consistent setup, side-to-side difference, change from baseline, pain response and compensation during maximal effort.
Force as percentage of body weight
Use when calculated directly from test force and body weight. It may help compare the client’s result to their own baseline, the opposite side and body size. Do not treat it as a universal target unless the comparison data use a closely matched protocol.
Torque
Use only when the lever arm is measured and a more biomechanical interpretation is needed. It can help when lower-leg length or device placement changes the raw force reading. It should not be used as normative data unless the reference data match the setup closely.
Rate of force development
Use when rapid hip rotation force matters, such as cutting, pivoting, kicking or change of direction. Look for early force production and whether rate of force development changes while peak force stays similar.
Time to peak
Use to understand whether force is produced quickly or gradually. Look for delayed peak force, faster time to peak across retests, and whether a slower time reflects caution, pain, poor cueing or an actual performance difference.
Impulse
Use only if a defined sustained force window is intentionally tested. Look for whether the client can sustain hip internal rotation force briefly and whether impulse improves while peak force stays similar.
Fatigue index
Use only if repeated or sustained hip internal rotation efforts are part of the protocol. Look for drop-off across repeated trials, symptom-related fatigue and whether fatigue improves across a training block.
Youth clients
Consider growth, maturation, coordination, attention, training age and familiarisation. Practice trials are important because hip rotation effort can be difficult to isolate without pelvis movement.
Adults and general fitness clients
Use the test for baseline hip rotation strength, progress tracking and confidence with loading. Compare results with hip mobility, trunk control, lower-limb strength and general exercise goals.
Older adults
Consider walking confidence, turning, transfers, balance, stairs, fatigue, rest periods and function. A lower score may provide useful context, but it should not be interpreted without functional assessment.
Athletes and sport clients
Consider running, kicking, cutting, pivoting, skating, change of direction and sport-specific hip rotation demands. Peak force alone does not equal sport performance, but it can support a broader lower-limb strength profile.
Workplace and manual task clients
Consider stairs, ladders, turning, stepping, carrying, uneven ground, walking distance and repeated lower-limb rotation demands. Do not use one score to clear work duties.
Clients returning after injury
Use the test to monitor force output, confidence and symptom response. Strength alone should not confirm readiness.
Clients with pain or persistent symptoms
Pain, fear, guarding, fatigue, apprehension and confidence may reduce force. Record symptom response carefully and compare with related tests.
Higher body mass clients
Absolute force and force relative to body mass may both be useful. Interpret results in relation to goals, symptoms and functional demands, not assumptions about body size.
Repeatability improves when the same setup is used each time. Record and standardise:
Same prone position
Same pelvis position
Same trunk position
Same hip angle
Same knee angle
Same lower-leg start position
Same device placement
Same strap setup, if used
Same anchor height and distance, if straps are used
Same strap angle, if straps are used
Same stabilisation
Same instructions
Same contraction duration
Same rest period
Same scoring method
Same symptom and compensation recording
Hip rotation strength testing is setup-dependent. Small changes in hip angle, pelvis control, lower-leg position or device contact point can change the score. For stronger clients, handheld resistance may be limited by professional strength. Strap-stabilised or fixed setups can improve repeatability.
Common errors include:
Pelvis lifting or rotating
Lower-back extension
Trunk shifting
Knee angle changing
Ankle pushing instead of hip rotation
Device placement changing between trials
Strap or anchor movement
Breath holding
Testing through high pain or cramping
Comparing prone, supine and seated protocols directly
Treating the score as a diagnosis
Limitations include:
Testing is setup-dependent
Manual resistance may be limited by professional strength
Muscle Meter-specific universal norms may be limited
Published hip internal rotation norms vary by device, position and population
Pain, fear or guarding can reduce force output
Peak force does not measure endurance or movement quality
Strong symmetry does not automatically indicate readiness for sport or work
The Prone Hip Internal Rotation Strength Test may be useful for:
Baseline hip rotation strength assessment
Side-to-side comparison
Monitoring response to exercise or intervention
Comparing internal rotation with external rotation where relevant
Supporting walking, running, kicking, pivoting and cutting assessment reasoning
Comparing with hip mobility, trunk control and functional tasks
Sport and workplace strength profiling
Client education
Fitness and performance progress tracking
If force is low on both sides, consider assessing hip rotation range of motion, external rotation strength, trunk control, gait, stairs, running exposure and confidence with loading.
If one side is much lower, compare with symptoms, injury history, hip mobility, external rotation strength, single-leg tasks, pivoting, kicking, cutting and work or sport demands.
If pain or cramping limits the result, record symptom location and review whether device placement, hip position or effort level needs modification.
If force is good but function is limited, compare with gait, running mechanics, cutting, kicking, balance, workload and task exposure.
If the client is improving, keep the same test setup and monitor whether force, symptoms, confidence and function improve together.
Position: Prone, pelvis and trunk controlled
Start position: Hip near neutral, knee commonly flexed to approximately 90 degrees
Joint or trunk angle: Record hip, knee, pelvis and trunk position
Trials: 1–2 practice trials, then 2–3 recorded trials
Contraction duration: 3–5 seconds
Rest: 30–60 seconds between efforts
Metric: Peak force, plus percentage of body weight if directly calculated
Attachment or device setup: Muscle Meter against distal lower leg or ankle region, with consistent contact point; strap-stabilised if used
Final score: Best trial or average of trials
Key retesting requirement: Same prone position, pelvis control, hip angle, knee angle, device placement, instructions, contraction duration, rest and scoring method
It measures isometric hip internal rotation force output in a specific prone setup.
The prone position allows the hip to be tested near neutral while the lower leg acts as the lever. It can be useful when comparing hip rotation strength side to side or direction to direction.
It can be if you calculate it directly from test force and body weight. This is useful for internal comparison, especially when tracking change over time.
Published universal Muscle Meter norms for this exact protocol appear limited. Baseline, side-to-side comparison and repeated testing are usually more useful.
Published comparison data include hip internal rotator force around 23.82% body weight in young women, and original article reference values of about 49 N for men and 35 N for women in healthy young adults. These are not direct Muscle Meter targets unless the setup is closely matched.
No. It can measure force output and symptom response, but it does not diagnose a condition or explain symptoms on its own.
Pelvis rotation, lower-back extension, ankle pushing, different knee angles, device slipping, pain, fatigue and inconsistent instructions can affect results.
Record side, prone position, hip angle, knee angle, device placement, peak force, percentage bodyweight if calculated, symptoms, compensations, confidence, scoring method and related findings.
The Prone Hip Internal Rotation Strength Test measures isometric hip internal rotation force output.
Peak force is usually the main routine Muscle Meter metric.
Published comparison data include 23.82% body weight in young women and approximately 49 N for men and 35 N for women in healthy young adults, but protocols vary.
Percentage of body weight should only be used when calculated directly from force and body weight or when comparison data are reported that way.
Baseline comparison, side-to-side comparison and retesting consistency are usually more useful than broad norms.
Reference values provide context, not diagnostic or clearance cut-offs.
Measurz should capture setup, symptoms, bodyweight-normalised values where calculated, compensations and retesting conditions.
Alvarenga, G., Kiyomoto, H. D., Martinez, E. C., Polesello, G., & Alves, V. L. S. (2019). Normative isometric hip muscle force values assessed by a manual dynamometer. Acta Ortopédica Brasileira, 27(2), 124–128. https://doi.org/10.1590/1413-785220192702202596
Hoglund, L. T., Wong, A. L., & Rickards, C. (2014). The impact of sagittal plane hip position on isometric force of hip external rotator and internal rotator muscles in healthy young adults. International Journal of Sports Physical Therapy, 9(1), 58–67.
Katz-Leurer, M., Rotem, H., Keren, O., & Meyer, S. (2009). The relationship between hip internal rotation strength and lower limb function in young adults. Journal of Bodywork and Movement Therapies, 13(2), 123–128.
McNabb, K., Sánchez, M. B., Selfe, J., Reeves, N. D., & Callaghan, M. (2024). Handheld dynamometry: Validity and reliability of measuring hip joint rate of torque development and peak torque. PLOS ONE, 19(8), e0308956. https://doi.org/10.1371/journal.pone.0308956
World Physiotherapy. (2019). Normative values for isometric hip muscle force assessed by hand-held dynamometry. World Physiotherapy Congress Proceedings.
