Straight Leg Raise Test (Lasègue): Protocol and How to Interpret It

The Straight Leg Raise test, popularly known as the Lasègue test (SLR), is probably the best-known neurodynamic test for assessing low back pain with suspected radiation. It's simple, requires no equipment, and gives an initial indication of whether the nerve root or sciatic nerve is involved.

What does this test measure?

The SLR assesses the response of the sciatic nerve and the lumbosacral nerve roots (mainly L4-S1) when placed under tension by raising the leg with the knee extended, in supine position.

What matters isn't just "how high the leg goes" (which also provides information about hamstring flexibility), but above all whether the elevation reproduces radiating pain down the leg, not just local tension in the back of the thigh.

Equipment needed

• A treatment table
• Optional: goniometer to measure the exact angle of pain onset

Execution protocol

1. The client lies supine, with both legs extended and relaxed
2. Hold the ankle and raise the client's leg with the knee in full extension, slowly and in a controlled manner
3. Keep raising until the client reports pain or tension
4. Record the elevation angle (relative to the table) at which pain appears, and where they localize it (lower back, glute, back of the leg, down to the foot)
5. If the pain is radiating, you can add the Bragard test (ankle dorsiflexion) by slightly lowering the leg to confirm the neural component
6. Repeat on the opposite leg for comparison

Common mistakes

• Not differentiating between "normal hamstring tension" (a stretching sensation in the back of the thigh, common in almost everyone) and "radiating pain" (which suggests a neural component)
• Raising the leg too fast, without giving the client time to properly identify the sensation
• Not recording the angle of onset, losing the ability to compare over time

How to interpret the result

Angle / type of response	General interpretation
Radiating leg pain between 30-70° of elevation	Suggestive of radicular/sciatic tension — supports suspicion of a disc herniation with nerve root involvement
Only local hamstring tension, no radiating pain, even with a wide range	Muscular flexibility limitation, not necessarily neural
Radiating pain that improves with reduced ankle dorsiflexion (negative Bragard test in that position)	Lower probability of a purely neural component

A positive Lasègue between 30 and 70 degrees, with clear radiating pain below the knee confirmed by the Bragard test, is one of the classic findings associated with lumbar radiculopathy, and should be assessed in the context of a full neurological examination (strength, reflexes, sensation).

Relationship with other tests

The SLR almost always pairs with:

• Bragard test — immediate confirmation of the neural component
• Slump test — an alternative/complement in sitting position, useful if the SLR is inconclusive or the client has trouble lying down

Why measure the angle and record it

The pain onset angle in the Lasègue test is a highly sensitive marker of progress: a client who starts with pain at 35° and, after weeks of treatment, reaches 70° pain-free is showing a clear sign of objective improvement, beyond what they report subjectively. In Movalytics you can log this angle at each assessment and see it plotted on a progress chart.

Frequently asked questions

Is the Lasègue test painful? It creates tension, and in people with nerve root irritation it can reproduce radiating pain, but the test should be stopped as soon as that pain appears, without pushing further. Does a negative Lasègue rule out a disc herniation? It doesn't completely rule it out, but it reduces its likelihood, especially when combined with a normal neurological examination. Is the "normal" angle the same for everyone? Not exactly: hamstring flexibility varies widely between people, which is why what matters most isn't just the angle, but whether radiating pain appears and how that angle evolves over time in the same person.