The Isometric Seated Calf Raise Test measures how much force a client can produce when pressing the forefoot downward against resistance while seated with the knee flexed. This position is commonly used to provide more context around knee-flexed plantarflexion strength and soleus-biased force capacity, although the gastrocnemius and other plantarflexors still contribute.

This test can provide useful context for walking, running, jumping, landing, stair use, acceleration, deceleration, change of direction, calf strength profiling and progress tracking. The result can help professionals quantify calf force rather than relying only on visual observation or subjective resistance.

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 seated calf raise testing, peak force is usually the main metric. Force as a percentage of body weight is especially useful for this test because published seated isometric plantarflexion data are often reported relative to body weight. Rate of force development and time to peak may be useful when rapid calf force matters, such as running, jumping, acceleration or change of direction. Impulse may be useful if sustained force over a defined time window is intentionally tested. Fatigue index is only relevant if repeated or sustained calf efforts are part of the protocol.

The result can support assessment reasoning, baseline comparison and progress tracking, but it does not diagnose Achilles pain, calf strain, soleus injury, nerve involvement, plantarflexor weakness cause or readiness for running, sport or work on its own.

What Is the Isometric Seated Calf Raise Test?

The Isometric Seated Calf Raise Test is an isometric plantarflexion strength assessment where the client presses the forefoot downward into the Muscle Meter, foot plate or fixed setup while seated with the knee flexed.

The movement direction is ankle plantarflexion. The purpose of the test is to measure how much downward forefoot force the client can produce in a specific knee-flexed position.

Consistent setup matters because knee angle, ankle position, forefoot contact point, strap angle, seat height, body position, stabilisation and client effort can all affect the result. This test measures force output in a specific setup. It does not fully measure calf endurance, running capacity, tendon capacity, gait quality, jumping ability or movement quality on its own.

Step-by-Step Protocol / Practice

1. Prepare the client

Explain that the test measures how strongly they can press the forefoot downward into the Muscle Meter or fixed device while seated. Record baseline symptoms, calf discomfort, Achilles discomfort, foot symptoms, fatigue, recent activity, training load and confidence with maximal effort.

Use at least one submaximal practice trial so the client understands the direction of force and how to build force smoothly.

2. Set the client position

A common setup is seated with the hip flexed, knee flexed and ankle positioned consistently. The knee may be positioned around 90–110 degrees depending on the chosen protocol. The foot should be placed so the forefoot can push downward without the heel or body position changing unexpectedly.

Record:

• Seat height
• Hip angle
• Knee angle
• Ankle start position
• Foot position
• Forefoot contact point
• Whether footwear was worn
• Whether the opposite limb was supported
• Whether bodyweight was measured for normalisation

3. Set up the device or straps

For a handheld setup, the professional holds the Muscle Meter under or against the forefoot while the client presses downward. However, plantarflexion force can be high, so a strap-stabilised or fixed setup is preferred when possible.

If using a strap or fixed plate, record:

• Anchor point
• Strap angle
• Strap length
• Device position
• Foot plate position
• Whether the anchor moved
• Whether any pre-tension was used

Push, pull and strap-stabilised scores should be recorded separately unless the protocol supports direct comparison.

4. Place the device, strap or handle

Place the Muscle Meter or force contact under the forefoot, commonly under the ball of the foot or metatarsal head region. Use the same contact point at retest.

The force direction should be plantarflexion: the client presses the forefoot downward as if performing a calf raise, without lifting the body, changing hip position or shifting the knee.

5. Stabilise the position

Stabilise the thigh, knee and foot position so the client does not compensate with hip movement, knee extension, trunk leaning, foot sliding or whole-body pushing. The aim is controlled knee-flexed plantarflexion force.

For stronger clients, a fixed setup is strongly preferred because assessor-held devices may be difficult to stabilise.

6. Give clear instructions

Use consistent instructions such as:

“Press the ball of your foot down into the device as hard as you can and hold.”
“Build up smoothly, then push hard.”
“Keep your knee and hip position still.”
“Keep breathing.”
“Do not bounce or lift your body.”
“Tell me if you feel pain, cramping, tingling or anything unusual.”

Use the same wording at retest where possible.

7. Record trials

Use 1–2 practice trials, then record 2–4 maximal trials depending on the protocol. A common contraction duration is 3–5 seconds. Rest for 45–90 seconds between trials, or longer if cramping, symptoms or fatigue 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.

8. Identify invalid trials

Repeat or mark a trial as invalid if:

• The foot slips
• The heel lifts unexpectedly
• The knee angle changes
• The hip shifts
• The trunk leans or pushes
• 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

9. Record symptoms

Record calf pain, Achilles discomfort, foot discomfort, cramping, paraesthesia, confidence, apprehension and symptom response after testing. Do not repeatedly test through high pain, worsening symptoms or severe cramping.

For retesting, match the same position, device placement, strap setup, instructions, contraction duration, rest period, scoring method and symptom recording.

Why It Is Used

The Isometric Seated Calf Raise Test is used to quantify knee-flexed plantarflexion force output in a repeatable setup. It may be useful for:

• Baseline calf strength assessment
• Side-to-side comparison
• Bodyweight-normalised comparison
• Monitoring change over time
• Soleus-biased strength profiling
• Comparing seated and standing calf strength where relevant
• Supporting running, jumping and change-of-direction assessment reasoning
• Workplace context where walking, stairs, ladders or prolonged standing 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.

What It Measures

The test primarily measures isometric knee-flexed plantarflexion force output in the chosen setup. It reflects the client’s ability to press downward through the forefoot while seated with the knee flexed.

It may provide useful information about:

• Seated calf force capacity
• Soleus-biased plantarflexion strength context
• Side-to-side force difference
• Force relative to body weight
• Confidence producing calf force
• Pain response during resisted plantarflexion
• Change in force over time
• Relationship between strength and related functional tasks

It does not directly measure:

• Achilles tendon health
• Calf strain status
• Cause of calf or Achilles pain
• Running capacity
• Jumping ability
• Calf endurance
• Gait quality
• Readiness to return to sport or work

Understanding the Result, Reference Values and What to Look For

What a higher or lower result may suggest

A higher score may suggest greater knee-flexed plantarflexion force output in that specific test setup. A lower score may suggest reduced seated calf force output, but the reason should be interpreted carefully.

Lower force may be influenced by pain, apprehension, poor familiarisation, fatigue, cramping, guarding, inconsistent device placement, poor stabilisation, recent training load, reduced confidence or difficulty tolerating the test position.

One result should not be interpreted in isolation. Interpretation is strongest when the same setup is repeated over time and reviewed alongside symptoms, confidence, ankle ROM, calf endurance, standing calf raise strength, hopping, running exposure, workload and functional goals.

What can influence the result

Important influences include:

• Pain
• Apprehension
• Poor familiarisation
• Fatigue
• Cramping
• Guarding
• Poor stabilisation
• Different forefoot placement
• Different knee angle
• Different ankle position
• Different strap angle
• Seat height
• Footwear
• Breath holding
• Client confidence
• Professional strength if using handheld resistance

Normative, reference and comparative values

Published Muscle Meter-specific universal norms for the exact seated calf raise setup are limited. However, seated isometric plantarflexion has better bodyweight-normalised comparison data than many smaller foot tests.

More user-friendly comparison data include:

• In professional male rugby union players, combined-limb seated isometric plantarflexion strength averaged 193.1 kg, or 1.86 × bodyweight. This is the same as about 186% bodyweight.
• In the same study, forwards averaged 1.75 × bodyweight, or about 175% bodyweight, while backs averaged 2.00 × bodyweight, or about 200% bodyweight.
• These values are from professional male rugby athletes, so they are high-performance comparison data, not general-population targets.
• In everyday terms, a result around 150% bodyweight may be a useful practical benchmark for a well-trained person in some settings, while values closer to 175–200% bodyweight are more consistent with higher-level athletic examples. These should still be treated as context, not strict pass/fail cut-offs.
• For general clients, the most useful comparisons are usually the client’s own baseline, right-to-left difference, symptoms, confidence and repeated testing under the same setup.
• For side-to-side comparison, a difference of around 10% or more is often worth reviewing more closely in strength testing, especially if it matches symptoms, previous injury, confidence changes or functional differences. This is not a strict pass/fail cut-off.
• If force is recorded as a percentage of body weight in Measurz, record the setup carefully because bodyweight-normalised values are only meaningful when the position, device placement and scoring method are consistent.

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.

Practical interpretation priorities

Use this order:

1. Compare with the client’s own baseline.
2. Compare right and left sides when relevant.
3. Review force relative to body weight where calculated.
4. Consider symptoms during and after testing.
5. Consider confidence and effort quality.
6. Review whether compensations were present.
7. Compare with related strength, mobility or performance tests.
8. Relate the result to walking, running, jumping, sport, work or daily-life demands.
9. Retest under the same conditions to monitor change.
10. Do not use reference values as pass/fail criteria.

What to look at for each relevant Muscle Meter metric

Peak force
Use for maximum seated calf force output, baseline strength, side-to-side comparison, bodyweight-normalised 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
This is especially useful for seated calf raise testing. Look for changes over time, side-to-side differences and whether the result is improving relative to the client’s body weight. Use published bodyweight comparisons only when the protocol is reasonably similar.

Torque
Use only when the lever arm is measured and a more biomechanical interpretation is needed. It should not be used as normative data unless the reference data match the setup closely.

Rate of force development
Use when rapid calf force matters, such as acceleration, jumping, landing or change of direction. Look for early force production and whether RFD 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 plantarflexion force briefly and whether impulse improves while peak force stays similar.

Fatigue index
Use only if repeated or sustained seated calf efforts are part of the protocol. Look for drop-off across repeated trials, symptom-related fatigue and whether fatigue improves across a training block.

Assessing and Providing Context for Different Client Populations

Youth clients
Consider growth, maturation, coordination, attention, training age and familiarisation. Practice trials are important because maximal plantarflexion effort can be difficult to coordinate.

Adults and general fitness clients
Use the test for baseline calf strength, progress tracking and confidence with loading. Compare results with ankle mobility, calf endurance, walking tolerance and general exercise goals.

Older adults
Consider balance, transfers, walking confidence, 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, sprinting, jumping, landing, acceleration, deceleration and change-of-direction demands. Peak force alone does not equal sport performance, but seated calf force can support a broader lower-limb strength profile.

Workplace and manual task clients
Consider stairs, ladders, carrying, prolonged standing, uneven ground, walking distance and footwear 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, cramping, 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.

Reliability, Validity and Measurement Considerations

Repeatability improves when the same setup is used each time. Record and standardise:

• Same test position
• Same seat height
• Same foot support
• Same device attachment
• Same forefoot contact point
• Same strap setup, if used
• Same anchor height and distance, if straps are used
• Same strap angle, if straps are used
• Same knee and ankle position
• Same stabilisation
• Same instructions
• Same contraction duration
• Same rest period
• Same scoring method
• Same symptom and compensation recording

Seated plantarflexion force can be high, so handheld resistance may be limited by professional strength. Strap-stabilised, foot-plate or fixed setups usually improve consistency for stronger clients.

Common Errors and Limitations

Common errors include:

• Foot slipping
• Forefoot contact point changing between trials
• Knee angle changing
• Hip shifting
• Trunk leaning
• Pushing through the whole body
• Strap or anchor movement
• Device slipping
• Breath holding
• Testing through high pain or cramping
• Comparing different protocols directly
• Treating the score as a diagnosis

Limitations include:

• Testing is setup-dependent
• Manual resistance may be limited by professional strength
• Strap setup requires careful anchor control
• Muscle Meter-specific universal norms may be limited
• Published athlete norms may not apply to general clients
• 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

Practical Applications

The Isometric Seated Calf Raise Test may be useful for:

• Baseline calf strength assessment
• Side-to-side comparison
• Bodyweight-normalised comparison
• Monitoring response to exercise or intervention
• Supporting running, jumping and calf-capacity assessment reasoning
• Comparing seated and standing calf force where relevant
• Comparing with calf endurance, hopping, gait, ankle mobility and workload
• Client education
• Fitness and performance progress tracking

Ideas to Make the Result Better

If force is low on both sides, consider assessing ankle ROM, standing calf strength, calf endurance, balance, gait, walking tolerance, recent load and confidence with loading.

If one side is much lower, compare with symptoms, injury history, ankle mobility, calf endurance, hopping, running exposure and functional tasks.

If pain or cramping limits the result, record symptom location and review whether device placement, ankle position, knee angle or effort level needs modification.

If force is good but function is limited, compare with standing calf raise, hopping, jumping, running tolerance, workload, footwear and sport/work demands.

If the client is improving, keep the same test setup and monitor whether force, symptoms, confidence and function improve together.

Recommended Standard Protocol Summary

Position: Seated, hip flexed, knee flexed, foot supported
Start position: Forefoot on device or plate, ankle position recorded
Joint or trunk angle: Record hip, knee and ankle position
Trials: 1–2 practice trials, then 2–4 recorded trials
Contraction duration: 3–5 seconds
Rest: 45–90 seconds between efforts
Metric: Peak force, plus percentage of body weight where calculated
Attachment or device setup: Muscle Meter, foot plate or fixed setup under the forefoot with consistent contact point
Final score: Best trial or average of trials
Key retesting requirement: Same seat height, knee angle, ankle position, forefoot placement, instructions, contraction duration, rest and scoring method

FAQs

What does the Isometric Seated Calf Raise Test measure?

It measures isometric knee-flexed plantarflexion force output in a specific seated setup.

Why test calf strength seated?

The seated position reduces the contribution of the gastrocnemius compared with a straight-knee position and provides useful context for knee-flexed plantarflexion strength.

Should the result be recorded as percentage of body weight?

Yes, where possible. Bodyweight-normalised force is useful for this test because seated plantarflexion values are often interpreted relative to body weight.

What bodyweight values are available for comparison?

Professional male rugby players averaged about 1.86 × bodyweight, with forwards around 1.75 × bodyweight and backs around 2.00 × bodyweight in one seated isometric plantarflexion study. These are high-performance comparison values, not general-population cut-offs.

Can this test diagnose Achilles or calf problems?

No. It can measure force output, but it does not diagnose a condition or explain symptoms on its own.

Why is a fixed or strap-stabilised setup useful?

Calf force can be high. A fixed setup helps reduce the effect of professional strength and improves repeatability.

What can make the result unreliable?

Different foot placement, knee angle, ankle position, strap angle, seat height, device slipping, pain, cramping and inconsistent instructions can affect results.

What should be recorded in Measurz?

Record side, position, knee angle, ankle position, forefoot contact point, peak force, percentage bodyweight, symptoms, compensations, confidence, scoring method and related findings.

Key Takeaways

• The Isometric Seated Calf Raise Test measures knee-flexed plantarflexion force output.
• Peak force is usually the main routine Muscle Meter metric.
• Bodyweight-normalised force is especially useful for seated calf raise testing.
• Professional male rugby data reported approximately 1.75–2.00 × bodyweight, depending on playing group, with the whole group averaging 1.86 × bodyweight.
• These values are high-performance comparison data, not general-population pass/fail targets.
• Baseline comparison, side-to-side comparison and retesting consistency are essential.
• Measurz should capture setup, symptoms, bodyweight percentage, compensations and retesting conditions.

References

Lee, M., Lancaster, M., Tulloch, L., O’Leary, B., Power, E., Howes, D., Sourbuts, B., Berry, A., Maher, F., & O’Neill, S. (2023). Normative isometric plantarflexion strength values for professional level, male rugby union athletes. Physical Therapy in Sport, 61, 114–121. https://doi.org/10.1016/j.ptsp.2023.03.007

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. https://doi.org/10.1371/journal.pone.0140822

Ramsey, K. A., Warlow, O. M., & Alkjær, T. (2025). Excellent reliability for an instrumented test of ankle plantarflexion force. International Journal of Sports Physical Therapy, 20(1), 36–45. https://ijspt.scholasticahq.com/article/128591-excellent-reliability-for-an-instrumented-test-of-ankle-plantarflexion-force