# Seated Open Knee Leg Raise On A Chair - Canonical: https://fitwill.app/exercise/8313/seated-open-knee-leg-raise-on-a-chair/ - Media ID: 8313 - Primary muscle: Abs - Body part: Core - Equipment: Bench Or Seat - Video: https://fitwill.app/videos/8313/seated-open-knee-leg-raise-on-a-chair.mp4 ## Description The Seated Open Knee Leg Raise On A Chair is a simple bodyweight core exercise performed on an ordinary sturdy chair. You sit near the front edge of the seat, grip the sides of the seat for support, lean your torso back slightly, and draw both knees up toward your chest with your legs held apart, then lower them back down under control. Because the chair fixes your upper body in place, your abdominal muscles have to do the work of lifting and lowering the legs instead of your whole body moving. This movement trains the rectus abdominis — the front wall of the abdomen — along with the hip flexors at the front of the hip, particularly the iliopsoas and rectus femoris, which work together with the abs every time you raise your knees. The slight backward lean is what shifts the emphasis toward the abdominals: the more you round your lower back and tuck your pelvis as the knees come up, the more your abs contract; the more you simply swing the legs, the more the hip flexors take over. It is a good fit for people who find floor work uncomfortable, for office workers who want to train without getting down on the ground, for older trainees who need help getting up and down from the floor, and for beginners building the strength needed for hanging knee raises. The open-knee position, with the thighs apart rather than pressed together, gives the belly room to move and is often more comfortable during pregnancy, after eating, or for anyone with a larger midsection. Setup matters more than it looks. A chair without wheels, placed against a wall, keeps the base stable. Sitting too far back against the backrest limits your range of motion, while perching too close to the edge puts extra demand on balance. Your hands should press firmly down into the seat, your chest stays tall, and your shoulders stay relaxed away from your ears throughout the set. To execute the movement well, exhale as you pull both knees up toward your chest, letting them travel slightly outward because of the open position, and pause briefly at the top when your thighs are close to your torso. Lower the feet back to the floor slowly rather than dropping them, keeping tension in your midsection until your feet touch down. That controlled lowering phase is where most of the abdominal work actually happens, so treat it as part of the repetition, not just a return trip. In practice, this exercise works well as a warm-up for more demanding core training, as a standalone abdominal drill in home or hotel-room workouts, or as high-repetition finisher work. Keep the reps smooth and quiet — if the chair rocks, creaks, or slides, slow the tempo down before adding reps. ## Instructions 1. Place a sturdy, armless chair on a non-slip surface, ideally with its backrest against a wall so it cannot tip or slide. 2. Sit toward the front half of the seat with your feet flat on the floor, knees bent to roughly 90 degrees, and your legs about hip-width apart. 3. Grip the sides of the seat just outside your hips with both hands and lean your torso back slightly, keeping your chest lifted and shoulders down. 4. Brace your abdominal muscles as if bracing for a light nudge to the stomach, and keep your neck relaxed with your gaze forward. 5. Exhale and lift both knees up toward your chest at the same time, letting the knees stay open apart as they rise. 6. Continue until your thighs are close to your torso or you reach the highest point you can control without your lower back rounding into a slump. 7. Pause for a beat at the top and squeeze your abdominal muscles rather than letting your legs hang on your hip flexors. 8. Inhale and lower your legs slowly, resisting gravity the whole way down until both feet rest lightly on the floor. 9. Reset your grip and posture briefly between reps, then repeat for your target number of repetitions. 10. Keep the tempo steady throughout; if the chair starts to rock or your feet slam down, slow the movement before doing more reps. ## Tips & Tricks - The most common mistake is letting the legs do all the work with a stiff, upright torso. Press your hands down into the seat and tilt your pelvis back slightly as the knees rise so your abdominals round your lower spine instead of your hip flexors simply folding you at the hip. - If your feet drop quickly on the way down, your abs have checked out. Count two to three seconds on the lowering phase of every Seated Open Knee Leg Raise On A Chair and the difference in abdominal effort is immediate. - Avoid leaning your weight back onto the backrest mid-set. Once the chair back supports your torso, the exercise loses most of its core demand — stay propped on your hands and your own posture instead. - Shrugging your shoulders up toward your ears while gripping the seat is a common giveaway of fatigue. Drop your shoulders down and back between reps, and end the set when you can no longer hold them there. - Keep the knees genuinely open rather than letting them drift together. Pressing the knees toward each other as you lift shifts tension away from the intended path and makes the top position cramped. - If the seat is too high and your feet dangle at the start, put a low step or sturdy book under your feet so you can push off and control the bottom position. - Breathe out on the lift and in on the lower. Holding your breath through several reps is a sign the tempo is too fast for your current strength. - To make the exercise harder, straighten your legs slightly as you raise them or hold the top position for two to three extra seconds; to make it easier, raise one knee at a time. ## Frequently Asked Questions ### Which muscles does the Seated Open Knee Leg Raise On A Chair work? The primary muscles are the abdominals, especially the rectus abdominis at the front of your trunk. The hip flexors at the front of the hip, mainly the iliopsoas and rectus femoris, assist strongly every time the knees travel up toward the chest. ### Why should my knees stay open apart instead of together during the Seated Open Knee Leg Raise On A Chair? The open knee position gives your abdomen space to compress as your abs contract, which keeps the movement comfortable and lets you round your trunk properly at the top. Pressing the knees together tends to cramp the top position and shifts work toward the inner thighs and hip flexors. ### Is the Seated Open Knee Leg Raise On A Chair suitable for beginners? Yes, it is one of the most accessible knee raise variations because the chair supports your weight and there is no grip demand like there is on a pull-up bar. Beginners can start with one knee at a time or a smaller range and progress to lifting both knees to chest height. ### What kind of chair should I use for this exercise? Use a stable, armless chair without wheels that can hold your weight while you press down on the seat with your hands. Placing the backrest against a wall and sitting on a non-slip surface prevents the chair from sliding forward during the set. ### How do I make sure my abs are working and not just my hip flexors? Lean back slightly, press your hands into the seat, and deliberately tuck your pelvis under as your knees rise so your lower back rounds a little at the top. If your torso stays completely upright and rigid, the hip flexors are doing almost all of the lifting. ### How many repetitions of the Seated Open Knee Leg Raise On A Chair should I do? Start with 2 to 3 sets of 8 to 12 slow, controlled reps and build toward 15 to 20 per set as your control improves. Because the resistance is light, quality of the pelvic tuck and the lowering phase matters far more than the rep count. ### What can I use instead of a chair if I don't have one available? The same movement works on the edge of a sturdy bench, a stable ottoman, or a firm bed edge, as long as you can grip the surface beside your hips and your feet can reach a resting position. Avoid soft chairs or anything with casters, which can shift under you. ### Is it safe to do the Seated Open Knee Leg Raise On A Chair with lower back issues? Many people with stiff or sensitive lower backs find the supported seated position more comfortable than floor work, but comfort varies from person to person. Keep the range small, avoid any forcing of the knees up, and stop if the movement produces pain rather than muscular effort. ### How is this different from a hanging knee raise? A hanging knee raise demands grip strength and suspensory stability from the shoulders, while the chair version removes those demands and isolates the lifting action of the abs and hip flexors. It works well as a stepping stone toward hanging variations. ### Should my feet touch the floor between repetitions? Letting your feet lightly touch down between reps gives you a brief reset and keeps the movement controlled, which is a good default. Once you are stronger, you can hover the feet just above the floor for the whole set to keep constant tension on your abdominals.