The Isometric Single-Leg Squat Test measures how much force a client can produce when pushing against an immovable setup from a fixed single-leg squat position. It is commonly used to assess unilateral lower-limb force output and side-to-side differences in a controlled position.
This test can provide useful context for single-leg loading, running, jumping, landing, deceleration, change of direction, cutting, stair use, sport tasks, lower-limb strength profiling and progress tracking. Because it is a single-leg multi-joint test, the result reflects combined contribution from the hip, knee, ankle, trunk, balance strategy and confidence rather than one isolated muscle group.
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 isometric single-leg squat testing, peak force is usually the main metric. Force as a percentage of body weight or as a bodyweight multiple is useful because single-leg squat force is influenced by body mass. Side-to-side comparison is also especially important. Rate of force development and time to peak may be useful when rapid single-leg force matters, such as landing, cutting, sprinting and change of direction. Impulse may be useful if force over a defined time window is intentionally analysed. Fatigue index is only relevant if repeated or sustained single-leg squat efforts are part of the protocol.
The result can support assessment reasoning and progress tracking, but it does not diagnose knee, hip, ankle or back pathology, identify one specific weak muscle, predict performance with certainty, or determine readiness for sport or work on its own.
The Isometric Single-Leg Squat Test is a maximal isometric unilateral lower-limb assessment where the client pushes against an immovable setup from a fixed single-leg squat position. With the Muscle Meter, this may involve a fixed strap, belt, bar, platform, frame or anchor arrangement that allows the client to push hard without visible movement.
The movement intent is to push through one leg as if standing up from a single-leg squat, while the setup prevents movement. The hip and knee are flexed to a recorded angle, the trunk is controlled, the non-tested limb is positioned consistently and the client produces maximal force for a short, consistent duration.
Consistent setup matters because knee angle, hip angle, trunk angle, stance position, foot position, footwear, strap length, bar height, balance support, non-tested limb position, pre-tension, anchor stiffness and instructions can all affect the result. This test measures force output in a specific setup. It does not fully measure dynamic single-leg squat quality, landing quality, cutting skill, endurance, power, tissue status or sport/work readiness on its own.
Explain that the test measures how strongly they can push through one leg in a fixed single-leg squat position. Record baseline symptoms, knee discomfort, hip symptoms, ankle symptoms, lower-back symptoms, balance confidence, fatigue, recent training load, sport exposure and confidence with maximal effort.
Use at least 1–2 submaximal practice trials on each side so the client understands the position, balance strategy, bracing strategy and force direction. Familiarisation is important because unilateral testing is affected by confidence, balance and posture.
Position the client in a fixed single-leg squat stance. The exact depth should match the intended protocol and be recorded. Unilateral isometric squat research has used defined hip and knee flexion positions, and the same setup should be repeated at retest.
Record:
Test side
Stance width or foot position
Foot angle
Footwear
Knee angle
Hip angle
Trunk angle
Squat depth
Non-tested limb position
Balance support strategy
Bar, belt, strap or device height
Whether body weight was measured for normalisation
The client should feel stable enough to produce maximal force without losing balance or changing position.
Attach the Muscle Meter to a fixed anchor, strap, bar, belt, plate or frame that can tolerate high unilateral lower-limb force without moving. The setup should be strong, stable and repeatable.
Record:
Anchor point
Strap or chain length
Device position
Device orientation
Belt or bar position
Whether pre-tension was used
Whether the anchor or frame moved during testing
Push, pull, belt, strap, frame and force-plate results should be recorded separately unless the protocol supports direct comparison.
Position the device and attachment so the client can push in the intended force direction without the setup moving. Depending on the setup, the client may push into a bar, belt, platform or strap while the Muscle Meter records force.
The force direction should be clearly defined and repeated at retest. The client should push through the tested leg while maintaining the same single-leg squat posture.
The setup should be fixed rather than manually resisted. Ensure the anchor, strap, device and contact point remain stable.
The client should avoid bouncing into the effort, changing squat depth, shifting the pelvis, collapsing the knee, lifting the heel, using the non-tested limb, pulling strongly through balance support or changing trunk angle.
Balance support may be used if it improves safety and repeatability, but it should be light and recorded clearly.
Use consistent instructions such as:
“Set your single-leg squat position.”
“Take up the slack without pushing early.”
“Push through the floor as hard and as fast as you can.”
“Keep the same body position.”
“Use the support only for balance.”
“Keep pushing until I say stop.”
“Keep breathing where possible.”
“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 per side. A common contraction duration is 3–5 seconds. Rest for 1–3 minutes between maximal trials, especially for stronger or highly trained clients.
Test order should be recorded. If side order may affect fatigue or confidence, use a consistent order at retest.
Record whether the final score uses the best trial or the average of recorded trials. Best trial is commonly used for maximal strength testing, while average score may be useful for monitoring if applied consistently.
Repeat or mark a trial as invalid if:
The setup moves
The strap, anchor or frame shifts
The client changes squat depth
The client loses balance
The non-tested limb assists
The client pulls strongly through balance support
The heel lifts unexpectedly
The knee collapses or moves substantially
The pelvis shifts or rotates
The trunk angle changes dramatically
Pain or cramping limits effort
The client starts before the device is ready
The recording misses the peak effort
The protocol changes between sides or trials
Record knee symptoms, hip symptoms, ankle symptoms, lower-back symptoms, cramping, paraesthesia, balance confidence, apprehension and symptom response after testing. Do not repeatedly test through high pain, worsening symptoms or severe cramping.
For retesting, match the same side order, stance, squat depth, joint angles, device placement, strap setup, balance support, instructions, contraction duration, rest period, scoring method and symptom recording.
The Isometric Single-Leg Squat Test is used to quantify unilateral lower-limb force output in a repeatable squat position. It may be useful for:
Baseline unilateral strength assessment
Side-to-side comparison
Monitoring change over time
Single-leg force profiling
Supporting running, jumping, landing and cutting assessment reasoning
Supporting stair, step-down and single-leg loading assessment reasoning
Comparing with double-leg squat, knee extension, hip extension or hop findings
Sport and performance profiling
Workplace context where stairs, ladders, uneven ground, carrying or repeated single-leg loading is relevant
Client education
The test should support assessment reasoning. It should not be used as a stand-alone diagnostic, prediction or clearance measure.
The test primarily measures maximal isometric force output in a unilateral squat position. It reflects combined contribution from the quadriceps, gluteals, hamstrings, calves, trunk, balance strategy and side-specific confidence.
It may provide useful information about:
Single-leg peak force
Side-to-side force difference
Force relative to body weight
Rate of force development
Time to peak force
Impulse over a defined time window
Confidence producing force on one leg
Symptom response during maximal single-leg effort
Change in force over time
It does not directly measure:
One specific muscle group
Dynamic single-leg squat technique
Landing quality
Cutting ability
Hop performance
Tissue status
Injury risk
Endurance
Sport readiness
Work readiness
A higher score may suggest greater unilateral isometric squat force in that exact setup. A lower score may suggest reduced force output, but the reason should be interpreted carefully.
Lower force may be influenced by pain, apprehension, poor familiarisation, fatigue, recent workload, inconsistent squat depth, balance confidence, poor bracing, side-specific symptoms, ankle mobility, knee symptoms, hip symptoms, back symptoms, setup movement or use of the non-tested limb.
One result should not be interpreted in isolation. Interpretation is strongest when the same setup is repeated over time and reviewed alongside symptoms, confidence, body weight, double-leg squat, knee extension, hip extension, hop tests, balance, landing tasks, cutting tasks, running exposure and sport or work demands.
Important influences include:
Pain
Apprehension
Poor familiarisation
Fatigue
Recent training load
Balance confidence
Foot position
Footwear
Squat depth
Knee angle
Hip angle
Trunk angle
Pelvis position
Non-tested limb position
Balance support
Strap length
Pre-tension
Anchor stiffness
Device orientation
Instructions
Client intent
Breath holding or bracing strategy
Published Muscle Meter-specific universal norms for the isometric single-leg squat are limited. Most available unilateral isometric squat data come from force-plate or fixed-frame protocols, so values should be used as context only unless the setup is closely matched.
More user-friendly comparison data include:
A unilateral isometric squat reliability study tested 28 recreational sport athletes after familiarisation and used three trials on each limb at approximately 140° of hip and knee flexion.
In that study, peak force showed good reliability on both limbs, with ICC 0.93–0.94 and CV 5.44–5.70%. This supports peak force as the most practical routine metric when the setup is standardised.
Early rapid-force measures and impulse can be useful but are generally more sensitive to setup and processing than peak force. This means peak force is usually the best starting point for routine Muscle Meter monitoring.
A result equal to 1.0 × body weight means the tested limb is producing force roughly equal to body weight in that setup.
A result of 1.5 × body weight means the tested limb is producing roughly one and a half times body weight.
A result of 2.0 × body weight means roughly double bodyweight force. These are practical comparison points, not universal targets.
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, hop performance, running exposure or functional differences. This is not a strict pass/fail cut-off.
If comparing single-leg and double-leg results, remember that one single-leg result is not simply expected to equal half of a double-leg result. Balance, confidence, hip control and side-specific symptoms can change the result.
These values and comparisons are best used as context. They can help structure interpretation, but they should not be used as diagnostic, performance-prediction or clearance cut-offs.
Use this order:
Compare with the client’s own baseline.
Compare right and left sides.
Review peak force and force relative to body weight.
Check whether squat depth and joint angles were identical.
Consider symptoms during and after testing.
Consider balance confidence and effort quality.
Review whether compensations or setup movement occurred.
Review rate of force development if rapid force production is relevant.
Compare with double-leg squat, knee extension, hip extension, hop, balance or work-task tests.
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 single-leg squat force output, baseline strength, side-to-side comparison, bodyweight-normalised comparison and progress tracking. Look for best score or average score, consistent setup, side-to-side difference, change from baseline, symptom response and whether the setup remained stable.
Force as percentage of body weight
This is highly useful for the single-leg squat. Look for changes over time and whether each side’s relative force improves, stays stable or decreases. Use bodyweight multiples as practical context, not pass/fail criteria.
Torque
Torque is usually not the main routine metric for this multi-joint test unless a specific biomechanical setup and lever-arm calculation is intentionally used. It should not be used as normative data.
Rate of force development
Use when rapid single-leg force matters, such as landing, cutting, sprinting, jumping or change of direction. Look for early force production and whether RFD improves while peak force stays similar. RFD is more sensitive to setup and instructions than peak force.
Time to peak
Use to understand whether the client reaches peak force quickly or slowly. Faster time to peak may be useful in explosive sport contexts, but interpretation should include effort strategy and instructions.
Impulse
Use if force over a defined time window is intentionally analysed. This can help when the professional wants to know whether the client produces and sustains force across a short single-leg effort.
Fatigue index
Use only if repeated or sustained single-leg squat efforts are part of the protocol. Look for drop-off across repeated trials and whether the decline matches symptoms, fatigue or training load.
Youth clients
Consider growth, maturation, coordination, training age, balance confidence and task familiarity. Use strong familiarisation and conservative interpretation because technique and confidence strongly influence results.
Adults and general fitness clients
Use the test for baseline unilateral strength, progress tracking and force relative to body weight. Compare with double-leg squat, step-down, lower-limb strength, hop tests and general exercise goals.
Older adults
Consider balance confidence, knee symptoms, hip symptoms, ankle symptoms, back comfort, fatigue and functional tasks such as stairs and transfers. Use the test only when the setup is safe and appropriate.
Athletes and sport clients
Consider landing, sprinting, acceleration, deceleration, cutting, jumping and change-of-direction demands. Peak force and RFD can support performance profiling, but they do not predict performance with certainty.
Workplace and manual task clients
Consider stairs, ladders, uneven ground, carrying, kneeling, squatting, fatigue and task exposure. 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 symmetry alone should not confirm readiness.
Clients with pain or persistent symptoms
Pain, fear, guarding, fatigue, apprehension and confidence may reduce force. Record symptoms carefully and compare with related tests.
Higher body mass clients
Absolute force and force relative to body mass are both 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 test side order
Same foot position
Same footwear
Same squat depth
Same knee angle
Same hip angle
Same trunk angle
Same pelvis position
Same non-tested limb position
Same balance support
Same bar, belt or strap height
Same anchor setup
Same device orientation
Same pre-tension
Same instructions
Same contraction duration
Same rest period
Same scoring method
Same symptom and compensation recording
Unilateral isometric squat research supports peak force as a reliable metric when the protocol is controlled. Early rapid-force metrics can be useful, but they are more sensitive to sampling, filtering, instructions, starting strategy and balance.
Common errors include:
Squat depth changing between trials
Knee angle changing
Hip or trunk angle changing
Pelvis shifting
Non-tested limb assisting
Pulling strongly through balance support
Heel lift
Knee collapse
Strap or anchor movement
Bouncing or jerking into the effort
Not recording pre-tension
Inconsistent instructions
Testing through high pain
Comparing force-plate values directly with a different Muscle Meter setup
Treating the score as a complete performance prediction
Limitations include:
Testing is setup-dependent
Balance confidence can affect force
Anchor stiffness and strap stretch can affect the score
Muscle Meter-specific universal norms may be limited
Force-plate, rack, belt and strap-based values may not be directly interchangeable
Peak force does not identify which muscle limited the task
High symmetry does not automatically indicate readiness for sport or work
RFD and impulse require consistent force-time recording and processing
The Isometric Single-Leg Squat Test may be useful for:
Baseline unilateral lower-limb strength assessment
Side-to-side comparison
Bodyweight-normalised force comparison
Monitoring response to strength training
Supporting landing, cutting, running and acceleration assessment reasoning
Comparing with double-leg squat, knee extension, hip extension, hop and balance tests
Athletic profiling
Workplace single-leg loading profiling
Client education
Fitness and performance progress tracking
If peak force is low on one side, consider assessing knee extension strength, hip extension strength, ankle mobility, balance confidence, single-leg control, symptoms and technical familiarity.
If both sides are low relative to body weight, compare with double-leg squat, general lower-limb strength, recent workload and task demands.
If RFD is low but peak force is good, compare with jumping, landing, sprinting, acceleration or other rapid-force tasks before drawing conclusions.
If the setup moves or the client loses balance, improve the anchor, support strategy, strap position and familiarisation before retesting.
If symptoms limit the result, record symptom location, review setup tolerance and compare with related tests.
If the client is improving, keep the same test setup and monitor whether force, symptoms, confidence and performance tasks improve together.
Position: Fixed single-leg squat position
Start position: Squat depth, knee angle, hip angle and trunk angle recorded
Joint or trunk angle: Record knee, hip and trunk angles
Trials: 1–2 practice trials, then 2–3 recorded trials per side
Contraction duration: 3–5 seconds
Rest: 1–3 minutes between maximal efforts
Metric: Peak force, side-to-side difference, percentage/bodyweight multiple, and RFD/time to peak if relevant
Attachment or device setup: Muscle Meter connected to fixed strap, belt, bar, frame, plate or anchor
Final score: Best trial or average of trials, with bodyweight-normalised value recorded where possible
Key retesting requirement: Same side order, stance, squat depth, joint angles, balance support, setup, pre-tension, instructions, contraction duration, rest and scoring method
It measures maximal isometric force in a fixed unilateral squat position. It reflects single-leg lower-limb force production rather than one isolated muscle.
No. This test measures force in a fixed isometric position. It does not assess dynamic single-leg squat quality unless movement quality is recorded separately.
Yes, where possible. Relative force is useful because body size strongly influences absolute force.
A result of 1.0 × body weight means force roughly equal to body weight, 1.5 × body weight means roughly one and a half times body weight, and 2.0 × body weight means roughly double body weight. These are practical comparison points, not pass/fail cut-offs.
Published universal Muscle Meter norms for this exact setup appear limited. Force-plate and rack-based data are useful, but they should not be treated as identical to strap or Muscle Meter setups unless the protocol is closely matched.
Peak force is usually the main routine metric. Side-to-side difference and bodyweight-relative force are also very useful.
Changing squat depth, joint angles, side order, balance support, pre-tension, anchor stiffness, instructions, fatigue or symptoms can affect results.
Record side, stance, squat depth, knee angle, hip angle, trunk angle, support strategy, setup type, pre-tension, peak force, bodyweight-relative force, symptoms, compensations, confidence, scoring method and related findings.
The Isometric Single-Leg Squat Test measures maximal isometric force in a fixed unilateral squat position.
Peak force is usually the main routine Muscle Meter metric.
Side-to-side comparison and force relative to body weight are especially useful.
Research in recreational sport athletes reported peak-force reliability of ICC 0.93–0.94 and CV 5.44–5.70% when familiarisation and setup were controlled.
Practical bodyweight multiples such as 1.0 ×, 1.5 × and 2.0 × body weight can help explain results, but they are not pass/fail cut-offs.
Baseline comparison and retesting consistency are more useful than broad norms.
Measurz should capture setup, symptoms, bodyweight-normalised force, side-to-side difference, force-time metrics where relevant, compensations and retesting conditions.
Brady, C. J., Harrison, A. J., Flanagan, E. P., Haff, G. G., & Comyns, T. M. (2018). The unilateral isometric squat: Test reliability, inter-limb asymmetries, and relationships with limb dominance. Journal of Strength and Conditioning Research.
Brady, C. J., Harrison, A. J., & Comyns, T. M. (2018). A review of the reliability of biomechanical variables produced during the isometric mid-thigh pull and isometric squat and the reporting of normative data. Sports Biomechanics. https://doi.org/10.1080/14763141.2018.1452968
Lynch, A. E., Davies, R. W., Jakeman, P. M., Locke, T., Allardyce, J. M., & Carson, B. P. (2021). The influence of maximal strength and knee angle on the reliability of peak force in the isometric squat. Sports, 9(10), 140. https://doi.org/10.3390/sports9100140
Marcora, S., & Miller, M. K. (2000). The effect of knee angle on the external validity of isometric measures of lower body neuromuscular function. Journal of Sports Sciences, 18(5), 313–319.
McGuigan, M. R., Newton, M. J., Winchester, J. B., & Nelson, A. G. (2010). Relationship between isometric and dynamic strength in recreationally trained men. Journal of Strength and Conditioning Research, 24(9), 2570–2573.
