The Bowstring Sign, also called the Bowstring Test, Cram Test or popliteal pressure sign, is a neurodynamic assessment commonly used after a straight leg raise position. The examiner partially flexes the knee to reduce posterior thigh tension, then applies pressure in the popliteal fossa to assess whether familiar neural-type leg symptoms are reproduced. A positive finding may support suspicion of sciatic nerve or lumbosacral nerve-root mechanosensitivity when it matches the client’s history and neurological findings, but it does not diagnose lumbar radiculopathy or disc herniation on its own.

Introduction

Low-back-related leg pain can be complex. Symptoms may travel into the posterior thigh, calf or foot and may be influenced by lumbar nerve roots, peripheral nerve mechanosensitivity, local posterior thigh structures, hip symptoms, hamstring sensitivity or other factors.

The Bowstring Sign is a clinical neurodynamic test used to assess symptom response during a modified straight leg raise position. It is often described as a variation or refinement of the Straight Leg Raise test and is also known as the Cram Test, popliteal compression test or posterior tibial nerve sign. Educational and clinical summaries describe it as being used for suspected sciatic nerve or lumbosacral nerve-root irritation, but the diagnostic value of the exact Bowstring Sign is less well established than broader SLR and crossed SLR evidence.  

The test can support assessment reasoning when used carefully, but it should not be used to diagnose lumbar disc herniation, lumbar radiculopathy or sciatica on its own.

Quick Summary

• Test name: Bowstring Sign
• Also known as: Bowstring Test, Cram Test, popliteal pressure sign, posterior tibial nerve sign
• Region: Lumbar spine, posterior thigh, sciatic nerve pathway
• Test type: Neurodynamic / symptom provocation test
• Common use: Low-back-related leg pain, suspected sciatic nerve mechanosensitivity, suspected lumbosacral radicular symptoms
• Positive finding: Familiar posterior leg or neural-type symptoms reproduced by popliteal fossa pressure after SLR positioning
• Negative finding: No familiar neural-type symptoms reproduced
• Best used with: Straight Leg Raise, Slump Test, neurological screen, dermatomes, myotomes, reflexes, symptom behaviour and history
• Key limitation: High-quality diagnostic accuracy evidence for the exact Bowstring Sign is limited

What Is the Bowstring Sign?

The Bowstring Sign is a passive clinical test performed after a straight leg raise position.

A common version is:

• The client lies supine.
• The examiner performs a straight leg raise until symptoms or tension are reported.
• The knee is slightly flexed to reduce symptoms.
• Pressure is applied into the popliteal fossa.
• The test is considered positive if familiar neural-type symptoms are reproduced.

The reasoning is that knee flexion reduces hamstring tension, while popliteal fossa pressure may mechanically load or sensitise neural structures. If familiar posterior leg symptoms are reproduced, this may support suspicion of sciatic nerve or lumbosacral nerve-root mechanosensitivity.

The Bowstring Sign should be interpreted as part of a neurodynamic assessment rather than as a stand-alone diagnostic test.

Why It Is Used

The Bowstring Sign is used to help differentiate whether posterior leg symptoms may be influenced by neural mechanosensitivity rather than only hamstring or local posterior thigh tightness.

It may help professionals:

• explore low-back-related leg pain
• assess symptom response after SLR positioning
• compare neural-type symptoms with hamstring stretch symptoms
• support assessment reasoning around sciatic nerve mechanosensitivity
• decide whether further neurological screening is needed
• monitor symptom irritability over time
• record reproducible symptom behaviour in Measurz

It is most useful when combined with:

• symptom distribution
• neurological screen
• Straight Leg Raise
• Slump Test
• lumbar movement assessment
• history and aggravating factors
• pain behaviour
• sensory, strength and reflex findings
• functional tolerance

Current clinical guidance for suspected sciatica or lumbar radiculopathy emphasises careful history, pain location, radiation, neurological symptoms and physical examination rather than reliance on one test.  

What It Assesses

The Bowstring Sign may assess:

• neural mechanosensitivity
• symptom response in a sciatic nerve pathway
• posterior leg symptom reproduction
• response to popliteal pressure
• relationship between SLR position and familiar symptoms
• irritability of low-back-related leg symptoms

It may be associated with:

• low-back-related leg pain
• sciatic nerve mechanosensitivity
• lumbosacral nerve-root irritation
• suspected lumbar radicular symptoms
• symptoms commonly described as sciatica

It does not directly assess or confirm:

• lumbar disc herniation
• nerve-root compression
• exact spinal level
• severity of neurological involvement
• tissue damage
• need for imaging
• readiness to return to sport or work

Who It Is Useful For

The Bowstring Sign may be useful for:

• exercise professionals
• strength and conditioning coaches
• allied health support teams
• movement assessment professionals
• sport and performance staff
• students learning neurodynamic assessment
• professionals using Measurz or MAT for structured assessment recording

It may be relevant for clients with:

• posterior thigh symptoms
• calf or foot symptoms linked with back pain
• suspected neural-type leg pain
• symptoms provoked by SLR or Slump positions
• low-back-related leg pain
• leg symptoms that change with spinal or neural loading positions

It should be used cautiously and within scope. If the client reports progressive neurological symptoms, severe weakness, saddle symptoms, bladder or bowel changes, unexplained severe pain or other red flags, further medical assessment is more appropriate.

When to Use This Test

Use the Bowstring Sign when you want to understand whether posterior leg symptoms are reproduced by neural loading in a modified SLR position.

It may be used during:

• low-back-related leg pain assessment
• neurodynamic assessment education
• comparison with Straight Leg Raise
• comparison with Slump Test
• reassessment of neural symptom irritability
• monitoring symptom response over time

It is most useful when the client reports symptoms such as:

• radiating posterior leg pain
• posterior thigh, calf or foot symptoms
• pins and needles or altered sensation
• symptoms affected by spinal position
• symptoms provoked by sitting, bending, SLR or Slump-like positions

When Not to Use or When to Be Cautious

Use caution or avoid testing when the client reports:

• severe or worsening neurological symptoms
• progressive weakness
• numbness in a concerning distribution
• saddle anaesthesia
• bladder or bowel changes
• unexplained weight loss, fever or systemic symptoms
• recent significant trauma
• suspected fracture or serious pathology
• severe pain at rest
• highly irritable symptoms where testing is likely to flare symptoms

Stop the test if:

• symptoms become severe
• symptoms spread unexpectedly
• neurological symptoms increase
• the client feels unsafe
• the client asks to stop
• the result would not change assessment reasoning
• further medical review is more appropriate

Equipment Required

No specialised equipment is usually required.

Useful resources include:

• plinth or firm surface
• pain rating scale
• body chart
• neurological screen record
• Measurz recording workflow
• optional goniometer or inclinometer for SLR angle
• optional symptom irritability notes

Step-by-Step Protocol / Practice

Setup

Explain the purpose of the test before starting.

Example wording:

“We are going to check whether a modified straight leg raise position and gentle pressure behind the knee reproduce your familiar leg symptoms. This test does not diagnose the cause on its own, but it helps us understand how your symptoms respond to neural loading.”

Client Position

Position the client:

• lying supine
• head supported if needed
• pelvis level
• non-tested leg relaxed
• tested leg relaxed before movement
• arms resting comfortably

Examiner / Professional Position

Stand beside the tested leg.

Ensure you can:

• control hip flexion
• support the leg
• monitor symptoms
• flex the knee slightly when needed
• apply controlled popliteal pressure
• stop the test quickly if symptoms escalate

Hand Placement

A common setup:

• one hand supports the distal leg or ankle
• the other hand controls the thigh or knee as needed
• after SLR symptom onset, one hand supports knee flexion
• the fingers or thumb apply pressure into the popliteal fossa

Avoid aggressive pressure. The aim is controlled symptom reproduction, not forceful compression.

Stabilisation

Maintain:

• controlled hip flexion
• neutral pelvis where practical
• relaxed ankle unless deliberately adding a sensitising movement
• consistent knee flexion angle during popliteal pressure
• no sudden jerking or bouncing
• clear communication throughout

Movement or Force Direction

The test sequence is:

• passively raise the straight leg into hip flexion
• stop when familiar symptoms or strong posterior tension appear
• slightly flex the knee until symptoms ease
• apply controlled pressure into the popliteal fossa
• monitor whether familiar posterior leg or neural-type symptoms return

Pressure direction is typically:

• anterior-to-posterior or direct pressure into the popliteal fossa region, depending on hand position
• controlled and gradual
• enough to provoke symptom response if sensitive, but not excessive

Instructions

Ask the client:

• “Tell me when you first feel symptoms.”
• “Where do you feel it?”
• “Is it your familiar symptom?”
• “Is it stretch, pain, tingling, numbness or something else?”
• “Tell me if symptoms increase too much.”

During popliteal pressure, ask:

• “Does this reproduce the same leg symptom?”
• “Is it the same location as your usual symptoms?”
• “Rate the symptom from 0 to 10.”

Positive Finding

A positive Bowstring Sign is usually:

• reproduction of the client’s familiar posterior leg, calf, foot or neural-type symptoms when pressure is applied in the popliteal fossa after SLR positioning

Record whether symptoms are:

• familiar or unfamiliar
• local or radiating
• pain, tingling, numbness, burning or pulling
• posterior thigh only or below the knee
• changed by knee flexion or popliteal pressure

Negative Finding

A negative Bowstring Sign is usually:

• no reproduction of familiar posterior leg or neural-type symptoms with popliteal pressure

The client may still feel:

• local pressure behind the knee
• hamstring stretch
• non-familiar discomfort
• mild posterior thigh tension

These should not automatically be interpreted as a positive neural finding.

Stopping Criteria

Stop if:

• symptoms are severe
• symptoms spread or worsen significantly
• neurological symptoms increase
• the client reports distress
• the client cannot relax
• the position is not tolerated
• symptoms are unclear and repeated testing is not appropriate

Safety Notes

The test should be performed slowly and respectfully.

Do not use sudden force. Do not repeatedly provoke severe symptoms. In highly irritable presentations, a gentler SLR or Slump assessment may be more appropriate, or testing may be deferred.

Positive and Negative Test Interpretation

Positive Test

A positive Bowstring Sign means popliteal fossa pressure after SLR positioning reproduces the client’s familiar neural-type leg symptoms.

A positive result may increase suspicion of:

• sciatic nerve mechanosensitivity
• lumbosacral nerve-root involvement
• low-back-related leg pain with neural features
• radicular-type symptom behaviour

A positive result is more meaningful when it matches:

• posterior leg pain distribution
• symptoms below the knee
• neurological findings
• positive SLR or Slump Test
• symptom change with spinal position
• dermatomal or myotomal findings
• reflex changes where relevant
• history consistent with nerve-root irritation

A positive result does not confirm:

• lumbar disc herniation
• lumbar radiculopathy
• nerve-root compression
• sciatica diagnosis
• exact spinal level
• need for imaging
• need for surgery

Other factors may contribute to symptoms, including:

• hamstring sensitivity
• local popliteal tenderness
• peripheral nerve sensitivity
• posterior thigh soft tissue pain
• hip-related symptoms
• heightened irritability
• fear or guarding

Negative Test

A negative Bowstring Sign means popliteal pressure does not reproduce familiar neural-type symptoms.

A negative result may reduce suspicion of neural mechanosensitivity if:

• SLR is also negative
• Slump Test is also negative
• neurological screen is normal
• symptoms are not below the knee
• lumbar movement does not reproduce leg symptoms
• functional tasks do not reproduce neural-type symptoms

However, a negative result does not fully exclude:

• lumbar radiculopathy
• disc-related symptoms
• intermittent nerve-root irritation
• load-dependent leg symptoms
• symptoms that only occur in sitting, bending, fatigue or higher loads

Further assessment may still be needed when history or symptoms remain strongly suggestive.

Sensitivity, Specificity and Diagnostic Accuracy

High-quality peer-reviewed diagnostic accuracy evidence reporting sensitivity, specificity and likelihood ratios for the exact Bowstring Sign appears limited.

Exact Bowstring Sign Evidence

A commonly cited older diagnostic study reported the Bowstring Test as positive in 69% of people with confirmed lumbar disc herniation and nerve-root compression, but that sample had a 100% prevalence of disc herniation. This design allows a rough sensitivity estimate but does not allow specificity or likelihood ratios to be calculated. Clinical summaries therefore caution that the stand-alone diagnostic value of the test is uncertain.  

Because that key Bowstring-specific evidence is older and limited, the test should be interpreted cautiously. Although more recent evidence was searched for, the most directly relevant evidence for the exact Bowstring Sign remains limited and should be interpreted with the study population, reference standard and design limitations in mind.

Related Straight Leg Raise Evidence

The Bowstring Sign is usually performed as a modification of the Straight Leg Raise. Evidence for SLR and crossed SLR is broader than evidence for the Bowstring Sign itself.

A Cochrane review on physical examination for lumbar radiculopathy due to disc herniation reported that physical examination tests may help estimate probability, but evidence is affected by heterogeneity, study quality and spectrum of disease.  

A systematic review of the pain provocation-based SLR for lumbar disc herniation, radiculopathy or sciatica also highlighted uncertainty around clinical utility and the need to consider population, reference standard and study design.  

Practical Diagnostic Accuracy Summary

For the exact Bowstring Sign:

• Condition or presentation: suspected lumbar disc herniation, lumbar radicular symptoms or sciatic nerve mechanosensitivity
• Population: evidence appears limited and often based on selected or specialist populations
• Test variation: modified SLR with knee flexion and popliteal pressure
• Reference standard: varies or is not consistently reported in accessible summaries
• Sensitivity: limited evidence; one older study reported 69% positivity in confirmed disc herniation
• Specificity: not well established for the exact Bowstring Sign
• Positive likelihood ratio: not available from strong evidence
• Negative likelihood ratio: not available from strong evidence
• Key limitation: insufficient high-quality diagnostic accuracy evidence for stand-alone use

How to Interpret This

The Bowstring Sign is best used as part of a cluster.

A positive test may increase suspicion when it matches history, SLR, Slump and neurological findings. A negative test may decrease suspicion when the broader examination is also negative. Neither result confirms or excludes lumbar radiculopathy, disc herniation or sciatica on its own.

Reliability and Validity

Reliability and validity evidence for the exact Bowstring Sign appears limited.

More evidence exists for related neurodynamic tests such as the Straight Leg Raise and crossed Straight Leg Raise. A 2022 systematic review and meta-analysis summarised reliability of SLR and crossed SLR in suspected lumbar radicular pain and noted the importance of standardised procedures when using these tests.  

Validity for the Bowstring Sign is mainly based on its relationship to:

• SLR positioning
• symptom reproduction
• neural mechanosensitivity reasoning
• comparison with neurological signs
• consistency with client history

Reliability is likely stronger when you standardise:

• SLR angle
• knee flexion angle
• pressure location
• pressure amount
• symptom wording
• whether ankle position is neutral or sensitised
• side tested first
• pain rating method
• criteria for a positive test

Interpretation is stronger when the test is combined with:

• neurological screen
• SLR
• Slump Test
• symptom distribution
• reflexes
• myotomes
• dermatomes
• lumbar movement findings
• functional behaviour

Common Errors and Limitations

Common errors include:

• calling the test diagnostic
• applying excessive popliteal pressure
• failing to ask whether symptoms are familiar
• recording “positive” for local pressure pain only
• not recording symptom location
• not comparing with SLR or Slump findings
• not screening neurological status
• not recording SLR angle
• moving too quickly
• repeatedly provoking severe symptoms
• ignoring red flags or progressive neurological symptoms

Limitations include:

• limited diagnostic accuracy evidence for the exact test
• positive findings may reflect non-neural structures
• local popliteal tenderness can confuse interpretation
• SLR angle and knee position affect symptom response
• symptom irritability can change results
• findings may vary between examiners
• a negative result does not exclude lumbar radiculopathy
• the test does not identify the exact spinal level or structure

Practical Applications

The Bowstring Sign can support:

• low-back-related leg pain assessment
• neurodynamic assessment education
• comparison between hamstring stretch and neural symptoms
• symptom irritability tracking
• communication about familiar symptom reproduction
• structured recording in Measurz
• decisions about whether further neurological assessment is needed

It may be useful in clients with:

• posterior thigh symptoms
• calf or foot symptoms
• symptoms affected by sitting or bending
• symptoms reproduced by SLR
• suspected sciatic nerve mechanosensitivity

It is less useful when:

• symptoms are local only
• posterior knee pressure is locally painful but not familiar
• symptoms are highly irritable
• neurological red flags are present
• the assessment question is return-to-sport clearance

How to Record This in Measurz

Record:

• test name: Bowstring Sign / Bowstring Test / Cram Test
• side tested: left or right
• result: positive, negative, unclear or unable to test
• starting SLR angle
• symptom onset angle during SLR
• knee flexion position used before popliteal pressure
• ankle position: neutral, dorsiflexed or other
• pressure location: popliteal fossa, medial/lateral bias if relevant
• pressure intensity: gentle, moderate or unable to standardise
• pain score during SLR
• pain score during popliteal pressure
• symptom location
• symptom quality:
  • pain
  • burning
  • tingling
  • numbness
  • pulling
  • stretch
• whether symptoms were familiar
• whether symptoms travelled below the knee
• comparison side
• neurological findings:
  • dermatomes
  • myotomes
  • reflexes
  • neural symptoms
• related tests:
  • Straight Leg Raise
  • Slump Test
  • lumbar movement assessment
  • femoral nerve tension test if relevant
• irritability
• compensations or guarding
• reason for stopping, if relevant
• confidence in result
• interpretation notes
• retest date
• referral or further assessment notes if appropriate

Recording these details improves:

• repeatability
• communication
• client education
• assessment reasoning
• monitoring over time
• team consistency
• reporting quality

Related Tests / Internal Links

• Bragard Sign Test
• Femoral Nerve Tension Test
• FAIR Test
• FADIR Test
• Hip Quadrant Test
• Piriformis Test
• Gaenslen Test
• Spine Function Index-10
• Oswestry Disability Questionnaire

FAQs

What is a positive Bowstring Sign?

A positive Bowstring Sign is reproduction of the client’s familiar posterior leg or neural-type symptoms when pressure is applied in the popliteal fossa after a straight leg raise position.

Is the Bowstring Sign the same as the Straight Leg Raise?

No. It is usually performed after or during a modified Straight Leg Raise. The knee is slightly flexed and pressure is applied behind the knee to assess symptom response.

Can the Bowstring Sign diagnose sciatica?

No. It may support suspicion of sciatic nerve or lumbosacral nerve-root mechanosensitivity when combined with history and other findings, but it does not diagnose sciatica on its own.

What does a negative Bowstring Sign mean?

A negative test means familiar neural-type symptoms are not reproduced with popliteal pressure. This may reduce suspicion in some contexts, but it does not fully exclude lumbar radiculopathy or low-back-related leg pain.

Is there good sensitivity and specificity evidence for the Bowstring Sign?

High-quality diagnostic accuracy evidence for the exact Bowstring Sign appears limited. Older evidence suggests possible sensitivity, but specificity and likelihood ratios are not well established for the exact test.

What should the Bowstring Sign be paired with?

It should be interpreted alongside Straight Leg Raise, Slump Test, neurological screen, symptom distribution, lumbar movement findings, pain behaviour and history.

Should the test reproduce back pain or leg pain?

The most relevant positive finding is reproduction of familiar neural-type leg symptoms, especially symptoms matching the client’s usual posterior thigh, calf or foot complaint. Local pressure discomfort behind the knee is not enough on its own.

Key Takeaways

• The Bowstring Sign is a neurodynamic test commonly used after Straight Leg Raise positioning.
• It involves knee flexion followed by pressure into the popliteal fossa.
• A positive finding is reproduction of familiar neural-type leg symptoms.
• A positive test may support suspicion of sciatic nerve or lumbosacral nerve-root mechanosensitivity.
• The test does not diagnose lumbar disc herniation, radiculopathy or sciatica on its own.
• Diagnostic accuracy evidence for the exact Bowstring Sign is limited.
• Reliability depends on standardised SLR angle, knee position, pressure location and symptom criteria.
• Measurz should record side, SLR angle, symptom location, symptom quality, popliteal pressure response, neurological findings and related tests.

References

Berthelot, J.-M., Darrieutort-Laffite, C., Le Goff, B., & Maugars, Y. (2020). Inadequacies of the Lasègue test, and how the Slump and Bowstring tests are useful for the diagnosis of sciatica. Joint Bone Spine, 87(6), 581–586. https://doi.org/10.1016/j.jbspin.2020.06.004

Cochrane. (2026). Physical examination for the diagnosis of lumbar radiculopathy due to disc herniation in patients with low-back pain and sciatica. https://www.cochrane.org/evidence/CD007431_physical-examination-diagnosis-lumbar-radiculopathy-due-disc-herniation-patients-low-back-pain-and

Devillé, W. L. J. M., van der Windt, D. A. W. M., Dzaferagić, A., Bezemer, P. D., Bouter, L. M. (2000). The test of Lasègue: Systematic review of the accuracy in diagnosing herniated discs. Spine, 25(9), 1140–1147. https://doi.org/10.1097/00007632-200005010-00016

Koppenhaver, S. L., et al. (2022). Reliability of the straight leg raise test for suspected lumbar radicular pain: A systematic review with meta-analysis. Musculoskeletal Science and Practice, 60, 102563. https://doi.org/10.1016/j.msksp.2022.102563

NICE Clinical Knowledge Summaries. (2025). Sciatica lumbar radiculopathy: Assessment. https://cks.nice.org.uk/topics/sciatica-lumbar-radiculopathy/diagnosis/assessment/

Scaia, V., Baxter, D., & Cook, C. (2012). The pain provocation-based straight leg raise test for diagnosis of lumbar disc herniation, lumbar radiculopathy, and/or sciatica: A systematic review of clinical utility. Journal of Back and Musculoskeletal Rehabilitation, 25(4), 215–223. https://doi.org/10.3233/BMR-2012-0333

Tawa, N., Rhoda, A., Diener, I. (2017). Accuracy of clinical neurological examination in diagnosing lumbo-sacral radiculopathy: A systematic literature review. BMC Musculoskeletal Disorders, 18, 93. https://doi.org/10.1186/s12891-016-1383-2