Knee Extension Stretch (Genu Flexum)

How to do it

1. Sit with the leg supported and let gravity stretch the back of the knee toward full extension (a footrest helps).
2. Supine: rest and actively press the back of the knee into the floor or couch; a small towel under the ankle adds leverage.
3. Add standing knee-extension work with a stretchy band.
4. Actively stretch the soleus and avoid prolonged sitting with bent knees.

Form cues

• Drive the back of the knee down toward the surface
• Avoid in patellofemoral pain if compression aggravates

Why this exercise helps

This routine combines relaxed positioning with active quadriceps work to practice the final part of straightening the knee. Supporting the ankle lets gravity provide a low, sustained extension stimulus, while pressing the knee down or working against a band adds muscular control. A separate bent-knee calf stretch may be useful when ankle motion also feels limited, but neither posture nor this drill can identify whether muscle length, strength, joint mobility, pain, or another factor restricts extension. A swollen, locked, or recently injured knee needs assessment rather than forceful stretching.

Stop or modify if

• Placing the rolled towel under the knee rather than under the ankle during passive work. The towel should elevate the ankle so gravity presses the back of the knee downward, not prop the knee into more flexion.
• Forcing the knee into a hard locked-out or hyperextended position. The goal is comfortable full extension; do not push past the point of mild resistance.
• Assuming the calf must be the reason the knee stays bent. Add the soleus stretch only if ankle motion feels limited and the position remains comfortable.

Modifications and progressions

• For passive seated extension, adjust the foot-rest height so that gravity works gently without any additional load, rather than adding a weight that creates discomfort.
• Skip any version that aggravates current knee pain. If pain, swelling, locking, or a hard movement block persists, seek clinical guidance before continuing.

Muscles worked

Stretches: hamstrings, soleus

Strengthens: quadriceps

Helps with

Related exercises