Seated isometric hip flexion is a still (isometric) exercise for the muscles at the front of your hip. You sit on a chair and try to lift one knee up against your own hand, and the hand stops it from moving. It works the hip flexors, including the front thigh muscle that crosses the hip (rectus femoris). The joint does not move, which is why it often turns up early in hip and knee rehab.

How to do the seated isometric hip flexion

Sit up straight on a sturdy chair, feet flat on the floor and knees at roughly a right angle.
Place the hand on the same side on top of your thigh, just above the knee.
Try to lift that knee up toward the ceiling while your hand presses down just as hard, so the leg stays where it is. The front of your hip and the top of your thigh should go firm.
Hold the push for about 10 seconds, breathing steadily the whole time.
Ease off slowly and relax, then repeat. Work the other leg as well if your program includes both.

What you should feel

Firm work in the crease at the front of the hip and along the top of the thigh, with no movement at the hip or knee.

Common mistakes

Holding your breath during the push.
Leaning back or slumping in the chair to help the lift.
Pushing harder than your hand can match, so the knee creeps up and the foot comes off the floor.
Letting go suddenly at the end instead of easing off.

How often

Many programs use 5 to 10 holds of about 10 seconds on each leg, once or twice a day, at a gentle to moderate effort to start. Your physio will adjust this.

Stop and check with your physio if

Sharp pain in the knee, or in the front of the hip or groin.
Your calf or thigh becomes swollen, warm, tender, red or darker than usual, or has a throbbing or cramping pain that feels different from normal muscle ache. Stop and get medical advice the same day, as this can be a blood clot. If you are also short of breath or have chest pain, call emergency services.

From the clinic

Your hand sets the effort. Build the push up over the first few seconds instead of going hard straight away. Stay at a level your hip and knee are comfortable with.

This is the sitting version of isometric hip flexion, which is done lying on your back. It is not the same as a quad set, where you tighten the thigh to press the back of the knee down into a towel. Your physio may give you both. If you have high blood pressure, breathe steadily through every hold and never hold your breath.

After a knee fracture or knee surgery, including a knee replacement, follow your surgeon's or physio's plan, and start this exercise only when they have cleared you. If you have had a hip replacement, get the go-ahead from your surgeon or physio before you try seated isometric hip flexion. Letting the knee creep up during the press takes the hip past a right angle, and many surgeons ask you to avoid that for the first months after some operations.

Written and checked by the PocketPhysio editorial team. Last updated 2026-09-26.

This page is general education, not a diagnosis or a personal treatment plan. If you have pain, an injury or a health condition, see a physiotherapist or doctor before starting new exercises.

Seated isometric hip flexion