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.
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.
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
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.
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.
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
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.
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
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
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
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.”
Position the client:
lying supine
head supported if needed
pelvis level
non-tested leg relaxed
tested leg relaxed before movement
arms resting comfortably
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
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.
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
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
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.”
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
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.
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
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.
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
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.
High-quality peer-reviewed diagnostic accuracy evidence reporting sensitivity, specificity and likelihood ratios for the exact Bowstring Sign appears limited.
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.
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.
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
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 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 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
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
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
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.
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.
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.
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.
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.
It should be interpreted alongside Straight Leg Raise, Slump Test, neurological screen, symptom distribution, lumbar movement findings, pain behaviour and history.
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.
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.
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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
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