Exercises for a buckling knee target the specific muscular and neuromuscular deficits that allow the knee to give way under load. For most people whose knee buckles without a significant structural injury (ligament tear, meniscal tear, loose body), the primary problem is insufficient quadriceps strength or activation alongside poor hip and ankle stability. These deficits are highly responsive to targeted exercise.
This guide provides a progressive exercise programme for knee buckling caused by muscular weakness and inhibition — the most common cause in both athletes and non-athletes. It pairs with the what causes a knee to buckle article on this site, which covers the full range of causes and the red flags that indicate when exercises alone are not the appropriate first step.
Important note: Before beginning a buckling knee exercise programme, any new or worsening buckling following an injury, buckling accompanied by significant swelling or locking, or buckling in an older adult at risk of falls should be assessed by a doctor or physiotherapist. This programme is appropriate for chronic or recurring buckling related to muscular weakness, not for acute structural knee injuries.
Why These Exercises Help
As covered in the what causes a knee to buckle article on this site, the most common non-structural cause of knee buckling is insufficient quadriceps strength or activation. The quadriceps are the primary active stabilisers of the knee during weight-bearing: they eccentrically control the rate of knee flexion during loading and provide the active support that prevents the knee from collapsing.
When the quadriceps are weak, inhibited by pain, or fatigued, they cannot adequately control the knee under load and buckling results. Strengthening the quadriceps is therefore the primary exercise intervention for most cases of knee buckling.
However, quadriceps strengthening alone is rarely sufficient. Three additional components must be addressed:
Hip strength: Gluteus medius and hip external rotator weakness allows the femur to adduct and internally rotate during loading, increasing the valgus stress on the knee that contributes to buckling. Hip strengthening reduces this valgus loading.
Proprioception and balance: Joint injury, pain, and disuse all impair the knee’s proprioceptive feedback, reducing the speed and accuracy of the automatic stabilising responses that prevent buckling. Proprioceptive training restores this feedback.
Eccentric control: The quadriceps must work eccentrically (lengthening under load) during the most demanding tasks that cause buckling: stair descent, slope walking, and deceleration. Eccentric-specific exercise is particularly important for people whose buckling occurs during these activities.
Phase 1: Basic Quadriceps Activation
These exercises are appropriate from the earliest stages of rehabilitation, including immediately following knee surgery or injury, and for people who cannot yet manage weight-bearing exercises without buckling.
Quad Set:
As covered in the what are quad sets article on this site, the quad set is the most fundamental quadriceps activation exercise.
How to do it:
- Lie flat on the back with the leg extended
- Tighten the quadriceps by pressing the back of the knee toward the floor
- Hold for 10 seconds
- Release completely
- Complete 3 sets of 10 per side, 3 to 4 times per day
Why first: The quad set re-establishes the neural connection to the quadriceps before any loaded exercise is introduced. In people with significant pain inhibition, this basic activation is often impaired and must be restored before anything else can be effective.
Straight Leg Raise:
As covered in the seated straight leg raise article on this site, the straight leg raise develops the quadriceps in the extended position with minimal knee joint loading.
How to do it:
- Lie on the back with one knee bent and the other leg extended
- Tighten the quad of the extended leg
- Lift the leg to the height of the bent knee
- Hold for 2 seconds
- Lower slowly
- Complete 3 sets of 12 per side
Short Arc Quad:
As covered in the how to strengthen vmo muscle article on this site, the short arc quad targets the VMO in the terminal extension range where it is most active as a patellar stabiliser.
How to do it:
- Lie on the back with a rolled towel under the knee creating approximately 30 degrees of flexion
- Extend the knee to full extension against gravity
- Hold for 2 seconds at full extension
- Lower slowly
- Complete 3 sets of 15 per side
Terminal Knee Extension:
As covered in the terminal knee extensions article on this site, the TKE develops the quadriceps in the standing terminal extension range most relevant to the gait pattern affected by buckling.
How to do it:
- Loop a resistance band behind the knee, anchored in front
- Stand with a slight knee bend
- Straighten the knee to full extension against the band
- Hold for 2 seconds
- Return
- Complete 3 sets of 15 per side
Phase 2: Progressive Weight-Bearing Strengthening
Once the basic activation is established and Phase 1 exercises can be completed with clear quadriceps activation, progress to weight-bearing exercises that develop the functional strength needed to prevent buckling during daily activities.
Mini Squat (0 to 30 Degrees):
As covered in the closed chain knee exercises article on this site, the mini squat develops the quadriceps in the terminal extension range with the foot on the floor.
How to do it:
- Stand with feet shoulder-width apart
- Lower to approximately 30 degrees of knee flexion
- Drive through both heels to return
- Focus the contraction on the inner quad (VMO)
- Complete 3 sets of 15
Wall Slide:
A supported squat that provides feedback about trunk position and limits the range to the safe zone for early rehabilitation.
How to do it:
- Stand with the back against a wall, feet 30 centimetres from the wall
- Slide down to 30 to 45 degrees of knee flexion
- Hold for 5 to 10 seconds
- Slide back up
- Complete 3 sets of 10
Step-Up (Low Box):
The step-up develops the concentric quadriceps and glute strength needed for stair ascent, which is typically less provocative than descent for people with buckling knees.
How to do it:
- Stand facing a step of 10 to 15 centimetres
- Step up with the affected leg, driving through the heel
- Control the return to the floor
- Complete 3 sets of 10 per side
Sit to Stand:
One of the most functionally important exercises for older adults with buckling knees. As covered in the closed chain knee exercises article on this site, this directly trains the movement most associated with fall risk from knee buckling.
How to do it:
- Sit at the edge of a chair
- Lean forward slightly
- Drive through both feet to stand
- Lower slowly and deliberately back to the chair
- Complete 3 sets of 10
The slow lowering is the most important part: The eccentric lowering develops the quadriceps control that prevents buckling during sitting down, which is one of the most commonly provocative activities.
Phase 3: Eccentric Loading
Buckling most commonly occurs during activities that require eccentric quadriceps control: stair descent, slope walking, deceleration, and sitting down. Specific eccentric loading develops the quadriceps in the exact function that is deficient.
Lateral Step Down:
As covered in the lateral step down exercise article on this site, this is one of the most evidence-based exercises for developing the eccentric quadriceps and hip control that prevents buckling.
How to do it:
- Stand sideways on a step of 15 to 20 centimetres on the affected leg
- Slowly lower the non-standing foot toward the floor over 3 to 4 seconds
- Touch the floor lightly and return
- Maintain the standing knee over the toes throughout
- Complete 3 sets of 10 per side
Why this is the most important Phase 3 exercise: Stair descent is the activity most commonly reported to trigger knee buckling. The lateral step down directly trains the eccentric control for this specific activity. Start with a lower step height and increase as strength develops.
Slow Eccentric Sit to Stand:
Add a slow eccentric lowering to the sit-to-stand exercise:
- Stand from the chair as described above
- Lower back to the chair over 5 to 6 seconds
- This slow eccentric challenges the quadriceps through the range most relevant to the sit-to-stand buckling pattern
- Complete 3 sets of 8
Single-Leg Mini Squat (Shallow):
Once bilateral mini squats are comfortable, introduce a shallow single-leg version to develop the unilateral eccentric control most relevant to the single-leg stance phase of walking.
How to do it:
- Stand on the affected leg
- Lower to approximately 20 to 30 degrees of knee flexion
- Maintain the knee over the toes
- Return under control
- Complete 3 sets of 8 per side
Phase 4: Hip Strengthening
As described above, hip abductor and external rotator weakness increases the valgus loading of the knee that contributes to buckling. The following exercises address the hip component alongside the quadriceps work.
Clamshell With Band:
As covered in the glute activation with bands article on this site.
3 sets of 15 per side. Daily if possible.
Lateral Band Walk:
As covered in the lateral band walk exercise article on this site.
3 sets of 15 steps per direction.
Single-Leg Glute Bridge:
As covered in the single leg glute bridge exercise article on this site.
3 sets of 10 per side.
Gluteus Medius Priority:
For people whose buckling is accompanied by a visible inward knee drift (valgus) during the step-down assessment, the hip exercises should be emphasised alongside the quadriceps work. Valgus during loading indicates the hip is contributing to the buckling pattern and must be addressed to prevent recurrence.
Phase 5: Balance and Proprioception
As covered in the balance drills for athletes article on this site, proprioceptive training restores the knee’s automatic stabilising responses that are impaired by injury, pain, and disuse.
Single-Leg Stance Progression:
- Single-leg stance on the floor, eyes open: 30 seconds per side
- Single-leg stance on the floor, eyes closed: 20 seconds per side
- Single-leg stance on foam pad, eyes open: 20 seconds per side
Progress to the next variation when the current one can be held consistently without buckling.
Step and Hold:
As covered in the balance drills for athletes article on this site.
Begin with a slow jog or brisk walk and decelerate to a single-leg hold for 3 seconds.
3 sets of 5 stops per side.
Tandem Walk:
Walk heel-to-toe for 10 steps, pause on one foot for 3 seconds, continue.
Develops the dynamic balance most relevant to walking stability.
The Complete Buckling Knee Programme
Phase 1 (Daily, Weeks 1 to 2):
- Quad set: 3 x 10 per side, 3 to 4 times per day
- Straight leg raise: 3 x 12 per side
- Short arc quad: 3 x 15 per side
- Clamshell with band: 3 x 15 per side
Phase 2 (3 to 4 times per week, Weeks 3 to 5):
- Mini squat: 3 x 15
- Wall slide: 3 x 10
- Step-up (low): 3 x 10 per side
- Sit to stand: 3 x 10
- Terminal knee extension: 3 x 15 per side
- Lateral band walk: 3 x 15 per direction
Phase 3 (3 to 4 times per week, Weeks 6 to 9):
- Lateral step down: 3 x 10 per side
- Slow eccentric sit to stand: 3 x 8
- Single-leg mini squat (shallow): 3 x 8 per side
- Single-leg glute bridge: 3 x 10 per side
- Single-leg stance progression: 3 x 30 seconds per side
Phase 4 (3 times per week, Weeks 10 to 12):
- Step-up (increasing height): 3 x 10 per side
- Lateral step down (increasing height): 3 x 10 per side
- Single-leg squat to box: 3 x 8 per side (as covered in the single leg squats article on this site)
- Step and hold: 3 x 5 per side
- Balance board single-leg: 3 x 20 seconds per side
What to Avoid
Avoid activities that consistently produce buckling without appropriate support: Walking on steep slopes, stair descent, and uneven ground are the activities most likely to produce buckling during the rehabilitation period. This does not mean avoiding them entirely, but performing them carefully with available support (handrail for stairs) until quadriceps strength is restored.
Avoid high-impact activities before strength is established: Running, jumping, and sport-specific movements should be deferred until the Phase 3 exercises can be performed without buckling.
Avoid pushing through buckling as if it is not happening: Each buckling episode is a fall risk and also provides a repetitive abnormal loading stimulus to the knee structures. Modifying the provocative activities while the programme is underway produces better outcomes than continuing to buckle repeatedly.
When Exercises Are Not Sufficient
The exercise programme above is appropriate when buckling is caused by muscular weakness or inhibition. Exercises are less likely to be sufficient as the primary treatment when:
- Buckling follows a specific injury and structural damage (ACL, MCL, meniscus) is likely
- Buckling is accompanied by significant swelling or locking
- The knee buckles even during low-demand activities (simple walking on flat ground) despite several weeks of consistent exercise
- Buckling is occurring in a pattern consistent with patellar instability (the knee giving way toward the inner side during pivoting)
- Significant neurological symptoms (weakness, numbness, tingling) accompany the buckling
In these situations, a physiotherapy or medical assessment is the appropriate next step to determine whether additional investigation or intervention is needed.
Frequently Asked Questions
How long does it take for buckling knee exercises to work?
Meaningful improvements in quadriceps activation and basic stability are typically felt within 2 to 4 weeks of consistent Phase 1 and 2 exercises. Meaningful reduction in buckling during provocative activities (stair descent, slopes) typically occurs within 6 to 8 weeks. Complete resolution of buckling and return to unrestricted activity typically takes 10 to 16 weeks depending on the degree of initial weakness and the specific activities involved.
Should I exercise through buckling or rest when it happens?
Rest when buckling occurs during an exercise. Each buckling episode during rehabilitation represents a loss of control that is both a safety concern and a signal that the exercise is too demanding for the current strength level. Reduce the difficulty, range, or speed of the exercise to the point where it can be performed without buckling, and build from there.
Can I do these exercises if I have knee arthritis?
Yes. The exercises in this programme are appropriate for most presentations of knee osteoarthritis and are in fact the primary conservative management strategy for arthritic knee buckling. Begin with the Phase 1 exercises and progress based on pain response. Keep pain below 3 to 4 out of 10 during and after each session. As covered in the closed chain knee exercises article on this site, closed chain exercises at pain-free ranges are well-tolerated by most people with knee OA.
Do I need a physiotherapist to do these exercises?
The Phase 1 and 2 exercises are safe and appropriate to begin independently for most people with chronic muscular-weakness-related buckling. For buckling that followed an injury, buckling in an older adult with fall risk, or buckling that has not improved after 4 to 6 weeks of consistent Phase 1 and 2 exercises, physiotherapy assessment provides the clinical guidance needed to progress appropriately and safely.
Will a brace help while I do these exercises?
A hinged knee brace or stability sleeve can reduce the frequency of buckling during daily activities while the strengthening programme is developing. This is a reasonable short-term accommodation, particularly for people whose buckling is affecting their ability to complete daily tasks safely. The brace should be viewed as a temporary support rather than a treatment: the exercises are the treatment.