The Shoulder Internal Rotation at 90° Strength Test measures how much force a client can produce when rotating the arm inward against resistance with the shoulder positioned at approximately 90 degrees of abduction. It is commonly used to assess isometric internal rotation force output in a more overhead or throwing-relevant shoulder position.
This test can provide useful context for throwing, swimming, racquet sports, pushing, striking, contact sport, overhead lifting, gym training, workplace overhead tasks, shoulder rotation profiling and progress tracking. The main contributors include subscapularis, pectoralis major, latissimus dorsi, teres major and anterior deltoid, with scapular control, trunk position, shoulder position, elbow angle and client confidence influencing the result.
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 shoulder internal rotation at 90° 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 shoulder rotation force matters, such as throwing, swimming, striking, grappling or contact sport. 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 internal rotation efforts are part of the protocol.
The result can support assessment reasoning and progress tracking, but it does not diagnose rotator cuff injury, subscapularis injury, shoulder instability, tendon pathology, nerve involvement, pain source or readiness for sport or work on its own.
The Shoulder Internal Rotation at 90° Strength Test is an isometric upper-limb strength assessment where the client rotates the forearm or hand forward/inward into the Muscle Meter, strap or fixed setup without visible shoulder movement. The shoulder is positioned at approximately 90 degrees of abduction, and the elbow is commonly flexed to approximately 90 degrees.
The movement direction is shoulder internal rotation. The purpose of the test is to measure how much inward rotational force the client can produce while holding a more elevated shoulder position.
Consistent setup matters because shoulder abduction angle, shoulder rotation angle, elbow angle, forearm position, device placement, lever length, trunk stabilisation, scapular position, strap angle and client effort can all affect the result. This test measures force output in a specific setup. It does not fully measure throwing capacity, swimming performance, rotator cuff integrity, scapular control, endurance, pain source or sport/work readiness on its own.
Explain that the test measures how strongly they can rotate the arm inward while the shoulder is held at approximately 90 degrees of abduction. Record baseline symptoms, shoulder pain, neck symptoms, elbow or wrist symptoms, paraesthesia, fatigue, recent throwing, swimming, pressing, racquet sport, overhead activity, recent training load and confidence with maximal effort.
Use at least one submaximal practice trial so the client understands the direction of force and learns to build force smoothly without trunk rotation, shoulder hiking, wrist pushing or breath holding.
Shoulder internal rotation at 90° can be tested seated, standing, supine or prone depending on the protocol and available setup. A common clinical setup is seated or standing with the shoulder abducted to approximately 90 degrees and the elbow flexed to approximately 90 degrees.
Record:
Seated, standing, supine, prone or other position
Test side
Shoulder abduction angle
Shoulder rotation start position
Elbow angle
Forearm position
Wrist position
Trunk position
Scapular position if observed
Device contact point
Whether a strap or fixed anchor was used
Whether symptoms were present before testing
The trunk should remain upright and stable where applicable. The client should avoid leaning, rotating the body, shrugging or changing the shoulder elevation during the effort.
For a handheld setup, the professional holds the Muscle Meter against the inside or front of the distal forearm, wrist or hand while the client rotates inward. For stronger clients or improved repeatability, a strap-stabilised, handle-based or fixed setup may be used.
If using a strap, handle or anchor, record:
Anchor point
Strap angle
Strap length
Handle position
Device position
Arm position
Whether any pre-tension was used
Whether the anchor, strap or handle moved during testing
Handheld, strap-stabilised, handle-based and fixed-frame scores should be recorded separately unless the protocol supports direct comparison.
Place the Muscle Meter against the inside or front of the distal forearm, wrist or hand depending on the selected lever length. Use the same contact point at retest. Avoid uncomfortable pressure over bony or sensitive areas.
The force direction should match shoulder internal rotation at 90° abduction. The client should rotate the forearm forward/inward into the device without moving the elbow, leaning the trunk, flexing the wrist or changing shoulder position.
Stabilise the trunk, scapular region and upper arm as appropriate so the client does not compensate with trunk rotation, shoulder horizontal movement, shoulder hiking, elbow movement, wrist flexion, grip squeezing or whole-body bracing.
The aim is controlled shoulder internal rotation force in the 90° abducted position.
Use consistent instructions such as:
“Rotate your arm inward into the device as hard as you can and hold.”
“Build up smoothly, then push hard.”
“Keep your elbow, shoulder height and body still.”
“Do not twist your trunk or push with your wrist.”
“Keep breathing.”
“Tell me if you feel shoulder pain, neck pain, tingling, weakness, dizziness 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. Some shoulder HHD research uses a 5-second maximal make contraction, while other practical protocols use 3 seconds. The chosen duration should be recorded and repeated consistently.
Rest for 30–60 seconds between trials, or longer if symptoms, fatigue, pain or apprehension 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 trunk rotates or leans
The shoulder shrugs significantly
The shoulder drops below or moves above the selected angle
The elbow moves away from the start position
The wrist flexes or pushes instead of shoulder rotation
The device, strap or handle slips
The strap or anchor moves
The client pushes with the body rather than the shoulder
Pain, paraesthesia or neurological symptoms limit effort
The client starts before the device is ready
The client holds their breath excessively
The professional cannot hold the device steady
Record shoulder pain, anterior shoulder symptoms, posterior shoulder symptoms, neck symptoms, elbow symptoms, wrist symptoms, paraesthesia, clicking, apprehension, confidence and symptom response after testing. Do not repeatedly test through worsening symptoms, significant paraesthesia, strong apprehension or high pain.
For retesting, match the same body position, shoulder abduction angle, shoulder rotation position, elbow angle, device placement, strap/handle setup, instructions, contraction duration, rest period, scoring method and symptom recording.
The Shoulder Internal Rotation at 90° Strength Test is used to quantify shoulder internal rotation force output in a more elevated shoulder position. It may be useful for:
Baseline rotator cuff and shoulder strength assessment
Side-to-side comparison
Monitoring change over time
Shoulder rotation strength profiling
Comparing internal rotation with external rotation at 90°
Supporting throwing, swimming, racquet sport, striking, overhead lifting and contact sport assessment reasoning
Supporting workplace assessment where overhead reaching or pushing is relevant
Tracking symptom response to resisted shoulder internal rotation
Client education
Fitness and performance progress tracking
The test should support assessment reasoning. It should not be used as a stand-alone diagnostic, injury-risk, performance-prediction or clearance measure.
The test primarily measures isometric shoulder internal rotation force output in the 90° abducted position. It reflects the client’s ability to produce inward rotational shoulder force while controlling trunk, scapular and arm position.
It may provide useful information about:
Shoulder internal rotation force capacity at 90° abduction
Side-to-side force difference
Internal-to-external rotation comparison at 90°
Force relative to body weight, if calculated
Confidence producing shoulder rotation force in an elevated position
Symptom response during resisted internal rotation
Change in force over time
Relationship between shoulder strength and overhead sport, work or daily-life tasks
It does not directly measure:
Cause of shoulder pain
Rotator cuff tissue status
Subscapularis integrity
Tendon pathology
Shoulder joint structure
Nerve function
Throwing readiness
Swimming performance
Work readiness
Sport readiness
A higher score may suggest greater shoulder internal rotation force output in that specific 90° 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, reduced confidence, neck symptoms, shoulder symptoms, scapular compensation, trunk rotation, elbow movement or professional strength if using manual resistance.
One result should not be interpreted in isolation. Interpretation is strongest when the same setup is repeated over time and reviewed alongside symptoms, confidence, shoulder range of motion, external rotation strength at 90°, internal rotation at side, abduction strength, scapular control, overhead exposure, sport demands and work tasks.
Important influences include:
Shoulder pain
Neck symptoms
Apprehension
Poor familiarisation
Fatigue
Guarding
Shoulder abduction angle
Shoulder rotation start position
Elbow angle
Forearm position
Lever length
Device or handle placement
Strap angle
Trunk stabilisation
Elbow movement
Wrist pushing
Scapular position
Breath holding
Client confidence
Professional strength if using handheld resistance
Published Muscle Meter-specific universal norms for shoulder internal rotation at 90° 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:
A large healthy adult shoulder HHD study reported shoulder internal rotation at 90° abduction at approximately 1.18 N/kg in females and 1.43 N/kg in males for the dominant arm.
In practical terms, a 70 kg person at 1.18 N/kg would produce about 83 N, or roughly 8.4 kg of force. A 70 kg person at 1.43 N/kg would produce about 100 N, or roughly 10.2 kg of force. These examples are useful for context, but the actual comparison should match sex, age, body size, protocol and arm position where possible.
The same study reported non-dominant internal rotation at 90° of approximately 1.28 N/kg in females and 1.42 N/kg in males. This suggests side-to-side comparison is useful, but dominance, sport exposure and testing consistency still need to be considered.
Internal rotation at 90° is usually lower than internal rotation at the side in this dataset. This shows why shoulder-at-side and 90° abduction tests should not be treated as interchangeable.
External rotation to internal rotation ratios at 90° abduction were reported around 0.71–0.86 across sex and age groups in healthy adults. This ratio can provide context for shoulder rotation balance, but it should not be used as a stand-alone target.
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, overhead exposure or functional limitations. This should not be used as a strict pass/fail cut-off.
If force is recorded as a percentage of body weight in Measurz, use it mainly for baseline comparison, side-to-side comparison and repeated testing under the same setup.
These values and comparisons are best used as context. They can help structure interpretation, but they should not be used as diagnostic, injury-risk, performance-prediction, clearance or pass/fail cut-offs.
Use this order:
Compare with the client’s own baseline.
Compare right and left shoulders while considering dominance and symptoms.
Review force relative to body weight where calculated.
Compare internal rotation with external rotation at 90° where relevant.
Compare 90° testing with shoulder-at-side testing only if both protocols are recorded separately.
Consider symptoms during and after testing.
Consider confidence and effort quality.
Review whether compensations were present.
Compare with shoulder range of motion and overhead task tolerance.
Relate the result to sport, gym, 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 shoulder internal rotation force output at 90° abduction, baseline strength, side-to-side comparison, internal-to-external rotation comparison and progress tracking. Look for best score or average score, consistent setup, change from baseline, symptom response and whether compensations occurred.
Force as percentage of body weight
Use only when calculated directly from test force and body weight. It may help internal monitoring and comparison between sides, but it should not be treated as a universal target unless the comparison data use the same protocol.
Torque
Use only when lever arm is measured and a more biomechanical interpretation is needed. It can help when contact point or arm length 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 shoulder internal rotation force matters, such as throwing, swimming, striking, grappling or contact sport. 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. A slower time to peak may reflect caution, pain, apprehension, poor cueing or a true force-production difference.
Impulse
Use only if a defined sustained force window is intentionally tested. It may help when the aim is to understand force maintained over a brief internal rotation contraction.
Fatigue index
Use only if repeated or sustained shoulder internal rotation efforts are part of the protocol. Look for drop-off across repeated trials and whether the decline matches symptoms, fatigue or apprehension.
Youth clients
Consider growth, maturity, coordination, sport exposure, confidence and familiarisation. Use conservative interpretation because effort, attention and testing confidence can influence the result.
Adults and general fitness clients
Use the test for baseline shoulder rotation strength, progress tracking and comparison with other shoulder directions. Compare results with range of motion, pushing tolerance, overhead tolerance, exercise exposure and symptoms.
Older adults
Consider comfort, shoulder mobility, neck symptoms, fatigue and confidence. Use a comfortable testing angle and avoid repeated maximal efforts if symptoms are provoked.
Athletes and sport clients
Consider throwing, swimming, racquet sports, combat sports, grappling, contact sport and overhead lifting demands. Shoulder internal rotation at 90° can support overhead strength profiling, but it should not be used alone to judge sport readiness.
Workplace and manual task clients
Consider pushing, pulling, lifting, carrying, reaching, overhead work and sustained arm positions. 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, body size, arm length and functional demands, not assumptions about body size.
Repeatability improves when the same setup is used each time. Record and standardise:
Same body position
Same test side order
Same shoulder abduction angle
Same shoulder rotation start position
Same elbow angle
Same forearm and wrist position
Same trunk stabilisation
Same scapular observation
Same device, strap or handle placement
Same anchor setup, if used
Same contraction duration
Same rest period
Same instructions
Same scoring method
Same symptom and compensation recording
Shoulder internal rotation at 90° is setup-dependent. Small changes in shoulder elevation, shoulder rotation start position, elbow angle, contact point, lever length or trunk stabilisation can change the score. For stronger clients, handheld resistance may be limited by professional strength. Strap-stabilised, handle-based or fixed setups can improve repeatability.
Common errors include:
Trunk rotation
Shoulder dropping below the selected angle
Shoulder hiking
Elbow moving away from the start position
Wrist flexion or hand pushing
Testing in a different shoulder position
Device or handle placement changing between trials
Breath holding
Testing through worsening symptoms
Strap or anchor movement
Poor familiarisation
Comparing shoulder-at-side and 90° abduction 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 shoulder internal rotation values vary by device, posture, arm angle and population
Pain, apprehension or guarding can reduce force output
Peak force does not measure endurance, coordination or throwing skill
Strong force or symmetry does not automatically indicate readiness for sport or work
The Shoulder Internal Rotation at 90° Strength Test may be useful for:
Baseline overhead shoulder rotation strength assessment
Monitoring response to exercise or intervention
Right-to-left shoulder strength comparison
Internal-to-external rotation profiling at 90°
Throwing, swimming, racquet sport and contact sport strength profiling
Occupational overhead strength profiling
Comparing with shoulder external rotation at 90°, internal rotation at side, abduction, flexion, range of motion and endurance tests
Client education
Fitness and performance progress tracking
If force is low on both sides, consider assessing shoulder range of motion, external rotation at 90°, internal rotation at side, abduction strength, scapular control, neck symptoms, throwing/swimming exposure and familiarisation.
If one side is lower, compare with symptoms, dominance, previous injury, sport or work demands, range of motion, external rotation strength and test setup.
If symptoms limit the result, record symptom location and type, review test angle and compare with related findings rather than forcing repeated maximal trials.
If internal rotation at 90° is strong but external rotation at 90° is low, consider the broader shoulder rotation profile and task demands rather than interpreting internal rotation alone.
If force improves but symptoms remain, consider reviewing endurance, range of motion, overhead workload, sport exposure and recovery between sessions.
If the client is improving, keep the same test setup and monitor whether force, symptoms, confidence and function improve together.
Position: Seated, standing, supine, prone or chosen shoulder internal rotation at 90° test position
Start position: Shoulder abducted to approximately 90 degrees, elbow commonly flexed to 90 degrees
Joint or trunk angle: Record shoulder abduction angle, shoulder rotation start position, elbow angle, trunk position and scapular observation
Trials: 1–2 practice trials, then 2–3 recorded trials per side
Contraction duration: 3–5 seconds, or 5 seconds if following the cited HHD normative protocol
Rest: 30–60 seconds between efforts; longer if symptoms occur
Metric: Peak force, side-to-side difference, internal-to-external rotation comparison, plus percentage of body weight if directly calculated
Attachment or device setup: Muscle Meter against distal forearm/wrist/hand or connected to a strap, handle or anchor with consistent contact point
Final score: Best trial or average of trials
Key retesting requirement: Same body position, side order, shoulder abduction angle, shoulder rotation start position, elbow angle, device placement, instructions, contraction duration, rest and scoring method
It measures isometric shoulder internal rotation force output with the shoulder elevated to approximately 90 degrees of abduction.
The 90° test places the shoulder in a more elevated position and is often more relevant to overhead or throwing positions. It should not be compared directly with the shoulder-at-side version unless both protocols are clearly recorded.
Key contributors include subscapularis, pectoralis major, latissimus dorsi, teres major and anterior deltoid, with scapular and trunk control also influencing the result.
Yes. Testing both sides allows side-to-side comparison, but dominance and sport exposure can influence shoulder rotation strength.
Healthy adult HHD data report shoulder internal rotation at 90° around 1.18 N/kg in females and 1.43 N/kg in males for dominant-arm testing. For a 70 kg person, this is roughly 8.4–10.2 kg of force, depending on the comparison value used. These are context values, not pass/fail targets.
Healthy adult ER ratios at 90° have been reported around 0.71–0.86. Use this as context, not as a strict target.
No. It can measure force output and symptom response, but it does not diagnose a condition or explain symptoms on its own.
Record side, position, shoulder abduction angle, shoulder rotation start position, elbow angle, device placement, peak force, symptoms, confidence, compensations, bodyweight-relative value if calculated, scoring method and related findings.
The Shoulder Internal Rotation at 90° Strength Test measures isometric internal rotation force in an elevated shoulder position.
Peak force is usually the main routine Muscle Meter metric.
Healthy adult HHD values include approximately 1.18 N/kg in females and 1.43 N/kg in males for dominant-arm internal rotation at 90°.
ER ratios at 90° around 0.71–0.86 may provide context but should not be used as pass/fail targets.
Shoulder-at-side and 90° tests should not be treated as interchangeable.
Percentage of body weight should only be used when calculated directly from force and body weight.
Measurz should capture side, setup, symptoms, force, confidence, compensations and retesting conditions.
Andrews, A. W., Thomas, M. W., & Bohannon, R. W. (1996). Normative values for isometric muscle force measurements obtained with hand-held dynamometers. Physical Therapy, 76(3), 248–259. https://doi.org/10.1093/ptj/76.3.248
Bradley, H., & Pierpoint, L. (2023). Normative values of isometric shoulder strength among healthy adults. International Journal of Sports Physical Therapy, 18(4), 977–988. https://doi.org/10.26603/001c.83938
Morin, M., Hébert, L. J., Perron, M., Petitclerc, É., Lake, S.-R., & Duchesne, E. (2023). Psychometric properties of a standardized protocol of muscle strength assessment by hand-held dynamometry in healthy adults: A reliability study. BMC Musculoskeletal Disorders, 24, 294. https://doi.org/10.1186/s12891-023-06400-2
Riemann, B. L., Davies, G. J., Ludwig, L., & Gardenhour, H. (2010). Hand-held dynamometer testing of the internal and external rotator musculature based on selected positions to establish normative data and unilateral ratios. Journal of Shoulder and Elbow Surgery, 19(8), 1175–1183. https://doi.org/10.1016/j.jse.2010.05.021
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. https://doi.org/10.1016/j.pmrj.2010.10.025
