The seated straight leg raise is an exercise performed sitting upright at the edge of a chair or treatment table, extending one knee from a bent position to fully straight, and then holding the leg extended or raising it slightly. It is one of the most commonly prescribed rehabilitation exercises across orthopaedic, neurological, and older adult contexts, and it is often the first active quadriceps exercise prescribed following knee surgery.
Its simplicity is deceptive. The seated straight leg raise occupies a specific niche in the exercise progression hierarchy that makes it the correct choice for specific situations, and understanding that niche determines when to use it and when to progress beyond it.
What the Seated Straight Leg Raise Is
The seated SLR is performed sitting in an upright position with both feet initially on the floor. One leg is extended at the knee until the leg is straight, and the straight leg is then either held in the extended position (as an isometric hold) or raised to a specific height above the horizontal.
The two primary versions:
Seated knee extension (seated SLR to horizontal): The primary version. The knee extends from the bent sitting position to full extension, bringing the leg to approximately horizontal. This is the most common clinical version.
Seated SLR with elevation: The knee extends to full extension and the leg is then raised above the horizontal into hip flexion. This version adds a hip flexion component to the knee extension movement and is used as a progression.
How the Seated SLR Differs From Other SLR Versions
Compared to the supine straight leg raise:
As covered in the supine hip flexion article on this site, the supine SLR is performed lying on the back with the leg raised from a horizontal starting position. In the supine version, gravity acts against the hip flexors to resist the leg raise. In the seated version, gravity acts against the knee extensors (quadriceps) to resist the knee extension movement. The muscle emphasis differs significantly: the supine version primarily challenges the hip flexors, while the seated version primarily challenges the quadriceps (VMO in particular).
Compared to the hanging straight leg raise:
As covered in the hanging straight leg raises article on this site, the hanging version requires the hip flexors to lift the full weight of the leg against gravity while hanging from a bar. The seated version is performed from a supported seated position where the hip flexors are not the primary challenge.
The seated SLR’s specific value: The seated position provides complete spinal support, zero balance demand, and a comfortable starting position that is achievable even by people in acute pain or immediately following surgery. It is specifically appropriate when the goal is isolated quadriceps activation in the most accessible possible context.
Muscles Targeted
Primary:
- Quadriceps (all four heads): The primary movement is knee extension, and all four quadriceps muscles drive the leg from the bent sitting position to full extension.
- VMO (vastus medialis oblique): As covered in the how to strengthen vmo muscle article on this site, the VMO is specifically active in the terminal extension range (the last 30 degrees of straightening the knee), making the seated SLR a VMO-relevant exercise.
Secondary:
- Hip flexors (iliopsoas, rectus femoris): If the leg is raised above horizontal in the elevated version, the hip flexors contribute to the lifting.
- Core (anti-extension): Provides trunk stabilisation in the upright seated position.
Clinical Applications
Post-Knee Surgery (Primary Application)
The seated SLR is the most commonly prescribed early quadriceps exercise following:
Total knee replacement: Following TKR, the quadriceps are significantly weakened by the surgery itself and by the pain inhibition that follows. The seated SLR is typically initiated within the first 1 to 3 days post-surgery as the first active quadriceps exercise because:
- The seated position is immediately accessible from a hospital bed or chair
- The movement does not require getting to the floor
- The range of motion is controllable (the knee does not need to flex beyond the starting seated position)
- The exercise can be performed with minimal pain at low range
ACL reconstruction: As covered in the closed chain knee exercises and open chain knee extension articles on this site, the quadriceps are significantly inhibited following ACL reconstruction. The seated SLR provides an early open chain quadriceps activation exercise at low load before the more demanding open chain machine extension and closed chain squat variations are reintroduced.
Post-arthroscopy: Following knee arthroscopy for meniscal repair, cartilage work, or diagnostic procedures, the seated SLR provides a gentle, pain-controlled quadriceps activation exercise during the early post-operative period.
Patellofemoral Pain Syndrome
As covered in the patellofemoral pain syndrome physical exercise article on this site, the seated SLR (particularly in the terminal extension range) provides quadriceps and VMO strengthening with minimal patellofemoral compressive forces. The terminal extension range (the final 30 degrees of straightening) produces the lowest patellofemoral joint stress, making the seated SLR appropriate during acute phases of PFPS when deeper knee flexion exercises are too painful.
Older Adult Hip and Knee Strengthening
The seated SLR is one of the most practically accessible exercises for older adults because:
- It can be performed in a standard chair without getting to the floor
- It does not require balance
- The intensity is gentle and controllable
- It develops both the quadriceps and hip flexors simultaneously in the elevated version
For older adults who cannot yet manage standing exercises, the seated SLR provides meaningful lower extremity strengthening in a completely safe position.
Hip Flexor Strengthening (Elevated Version)
As covered in the exercise for psoas muscle strengthening article on this site, the seated knee raise (which is essentially the elevated version of the seated SLR) is a primary exercise for psoas strengthening. By adding the elevation component to the seated SLR, the exercise develops the hip flexors in the range most relevant to walking, stair climbing, and athletic hip flexion demands.
Neurological Rehabilitation
In neurological rehabilitation (following stroke, multiple sclerosis, or other conditions affecting lower extremity motor control), the seated SLR provides a supported, controlled context for re-establishing the neural connection to the quadriceps and hip flexors. The seated position eliminates the balance demands that make standing exercises inaccessible in early neurological rehabilitation.
Step-by-Step Technique
Setup
- Sit upright at the edge of a chair, bench, or treatment table
- Both feet flat on the floor initially, knees bent at approximately 90 degrees
- Sit tall with the spine in a neutral position
- Hands can rest on the thighs or hold the sides of the chair for stability
- The target leg will be the working leg; the other foot remains flat on the floor throughout
The Movement
Phase 1: Knee extension
- Tighten the quadriceps of the working leg by contracting the thigh muscle
- Slowly straighten the knee, lifting the foot off the floor
- Continue extending until the knee is fully straight (0 degrees)
- The foot rises to approximately the level of the other knee or slightly above
Phase 2: Optional elevation (elevated version)
5. Once the knee is fully extended, raise the entire straight leg by flexing the hip
6. Lift until the leg is at approximately 45 degrees above horizontal or as high as hip flexor strength allows
7. Hold briefly at the top position
Phase 3: Controlled lowering
8. Lower the leg slowly under control, taking 3 to 4 seconds
9. If performing only the knee extension version, lower the foot back to the floor
10. If performing the elevated version, lower the entire straight leg back to the starting seated position
Sets and reps:
- Early rehabilitation (post-surgery, acute pain): 3 sets of 10 to 15 per side
- General strengthening: 3 sets of 12 to 15 per side
Key Technique Cues
Full knee extension at the top: The most important cue. The knee must reach complete extension (0 degrees) before any elevation is attempted. A knee that remains slightly bent at the top position is not achieving the terminal extension range where VMO activation is greatest.
Deliberate VMO contraction: At the top of the knee extension phase, deliberately tighten the inner quad (just above and to the inside of the kneecap) and hold for 2 to 3 seconds. As covered in the how to strengthen vmo muscle article on this site, the terminal extension hold is the most VMO-specific component of the exercise.
Upright posture throughout: The trunk should remain tall and upright throughout the movement. Leaning backward as the leg is raised is a hip flexor compensation pattern and reduces the effective isolation of the quadriceps.
Slow lowering: The eccentric phase (lowering the leg) is as important as the lifting phase. Count 3 to 4 seconds during the lowering and resist the urge to drop the leg quickly.
Controlled breathing: Breathe normally throughout. Holding the breath during the exercise is common in people with cardiovascular conditions and should be avoided.
Common Errors
Error 1: Incomplete Knee Extension
What it looks like: The knee remains slightly bent (5 to 10 degrees of flexion) rather than reaching full extension at the top.
Fix: Focus on the sensation of the knee locking out completely. Place the fingertips on the VMO above the knee to feel the muscle contracting at full extension. Reduce the rep count and focus entirely on achieving complete extension on each rep.
Error 2: Trunk Lean Backward
What it looks like: As the leg is raised (particularly in the elevated version), the trunk leans backward to assist the lift.
Fix: Place one hand on the lower abdomen to monitor for backward lean. Keep the chest up and the spine tall throughout. If backward lean persists, reduce the elevation height to the point where the trunk can remain upright.
Error 3: Dropping the Leg
What it looks like: The leg drops rapidly to the floor on each rep rather than being lowered under control.
Fix: Count to 3 or 4 during every lowering phase. If dropping occurs due to fatigue, reduce the reps per set rather than continuing with poor eccentric control.
Error 4: Hip Rotation
What it looks like: The hip rotates outward as the leg is raised, with the foot turning to the side.
Fix: Keep the knee and foot pointing forward (or very slightly outward at the hip’s natural angle) throughout the movement. External rotation indicates the hip external rotators are compensating for insufficient hip flexor strength in the elevated version.
Variations and Progressions
Level 1: Seated Knee Extension With Hold
Extend the knee to full extension and hold for 5 to 10 seconds before lowering. This isometric hold at terminal extension is the most basic version, appropriate for immediate post-surgical contexts and very weak quadriceps.
Sets and reps: 3 sets of 10 with 5-second hold
Level 2: Seated SLR to Horizontal (Standard)
As described above. Extend the knee fully and lower slowly. The standard version for most rehabilitation contexts.
Sets and reps: 3 sets of 15
Level 3: Seated SLR With Elevation
Add the hip flexion component after the full knee extension is achieved. The leg is raised to 45 degrees above horizontal.
Sets and reps: 3 sets of 12
Level 4: Seated SLR With Ankle Weight
Attach an ankle weight (0.5 to 2 kilograms) to the working ankle. The additional weight increases both the quadriceps demand during the extension and the hip flexor demand during the elevation.
How to progress: Begin with 0.5 kilograms and increase by 0.5 kilogram increments as the current weight becomes manageable for the full prescribed sets and reps.
Sets and reps: 3 sets of 12 per side
Level 5: Seated SLR With Band Resistance
Loop a resistance band under the foot and hold the ends to provide resistance against both the knee extension and the elevation.
Sets and reps: 3 sets of 10 to 12
Level 6: Transition to Standing Hip Flexion and Knee Extension Exercises
Once the seated SLR with resistance is well-established, transition to standing hip flexion with band (as covered in the exercise for psoas muscle strengthening article on this site) and the terminal knee extension (as covered in the terminal knee extensions article on this site) for the next level of functional hip flexor and quadriceps development.
Programming Guidance
For immediate post-surgical rehabilitation:
Daily, beginning within 1 to 3 days post-surgery (as directed by the treating team). Start with the isometric hold version and progress to the standard SLR within the first week as pain allows.
- Seated knee extension hold: 3 x 10 with 5-second hold
- Progress to full SLR without resistance as pain allows
For older adult hip and knee strengthening:
3 to 5 times per week as part of a seated exercise circuit:
- Seated SLR: 3 x 12 per side
- Seated marching (alternating hip flexion): 3 x 20 steps
- Seated calf raises: 3 x 15
For PFPS management:
3 times per week alongside the hip strengthening programme:
- Seated SLR (terminal extension emphasis): 3 x 15
- Combine with VMO-specific hold at terminal extension
For hip flexor strengthening (elevated version):
Daily or 4 to 5 times per week:
- Seated SLR with elevation: 3 x 12 per side, progressing to ankle weight
Progression pathway:
Week 1 to 2: Isometric hold version, 3 x 10, daily
Week 3 to 4: Standard SLR, 3 x 15, daily
Week 5 to 6: Elevated version, 3 x 12, 4 times per week
Week 7 to 8: Ankle weight (0.5 to 1 kilogram), 3 x 12
Week 9 to 10: Progress to standing exercises
Frequently Asked Questions
Is the seated straight leg raise the same as the quad set?
They are related but different. The quad set (as covered in the what are quad sets article on this site) is a purely isometric contraction where the knee remains on the floor and the quad is tightened without any joint movement. The seated SLR involves joint movement (knee extension) alongside the quad contraction. Both are used in early post-surgical rehabilitation but the quad set is typically introduced first, with the seated SLR as a progression once the isometric contraction is established.
Why is the seated version used rather than the lying version after knee surgery?
Both are used, but the seated version has practical advantages immediately post-surgery: the patient is often more comfortable sitting than lying, the seated position is immediately accessible in a hospital room without transferring to a treatment table, and the seated context is more functionally relevant to what the patient will be doing (sitting and standing from a chair) during early recovery. As rehabilitation progresses, both supine and seated variations are typically included for their complementary benefits.
How long should I hold the seated straight leg raise at the top?
For the isometric hold version in early rehabilitation: 5 to 10 seconds per hold. For the standard version with VMO emphasis: 2 to 3 seconds at full extension. For the elevated version: 1 to 2 seconds at maximum elevation. Longer holds increase the isometric endurance stimulus; shorter holds with more reps increase the dynamic strength stimulus.
Can I do seated straight leg raises with knee osteoarthritis?
Yes. The seated SLR is one of the most appropriate exercises for knee OA because it develops quadriceps strength (which reduces knee joint loading during functional activities) without requiring deep knee flexion or impact loading. Begin with the basic extension version and progress as tolerated. If the exercise consistently produces significant knee pain, reduce the range or seek physiotherapy guidance.
When should I progress beyond the seated straight leg raise?
Progress when 3 sets of 15 can be completed with full knee extension, controlled lowering, and clear VMO activation, and when the ankle weight version is no longer sufficiently challenging. The standing functional exercises (terminal knee extension, step-ups, mini squats) are the natural progressions and provide more functional specificity than continued progression of the seated version alone.