# Lying Knee Raise - Canonical: https://fitwill.app/exercise/8194/lying-knee-raise/ - Media ID: 8194 - Primary muscle: Abs - Body part: Core - Equipment: Body Weight - Video: https://fitwill.app/videos/8194/lying-knee-raise.mp4 ## Description The Lying Knee Raise is a simple floor-based core exercise where you lie flat on your back and draw your knees in toward your chest, then lower them back down under control. Because you start with your legs extended along the floor and finish with the knees tucked close to the torso, the movement takes the hips through a large range while the abdominals work to control both the lift and the return. This exercise trains the lower portion of the rectus abdominis along with the hip flexors, including the iliopsoas, which pulls the thighs toward the pelvis. The deep core muscles stay busy throughout, bracing the spine against the floor as the legs move. Compared with a full leg raise, bending the knees shortens the lever, which makes the movement easier to control and friendlier for people still building abdominal strength. The Lying Knee Raise suits beginners learning to feel their lower abs working, and it also works well as a warm-up or higher-rep finisher for experienced lifters. It requires nothing more than floor space, so it fits home workouts, hotel-room sessions, and the end of a gym session alike. Placing a mat under you makes the position more comfortable on the lower back and tailbone. Setup matters more than it looks. Lying flat with the arms relaxed at the sides anchors the upper body, and pressing the lower back gently into the floor before each rep keeps the spine neutral. If the back arches as the legs lower, the hip flexors take over and the lumbar spine absorbs stress that the abs should be handling. Keeping the movement slow and the back flat is what separates a good knee raise from a rushed one. To perform it well, exhale as you pull the knees up toward the chest, let the hips curl slightly off the floor at the top, and pause briefly before lowering. On the way down, extend the legs gradually while resisting gravity rather than dropping them. Breathe steadily, keep the head resting on the floor, and reset the lower-back contact between reps. The main safety point is lumbar control. If you feel straining or arching in the lower back, bend the knees more, reduce the range, or slow the lowering phase. Stop short of any pinching sensation at the front of the hips, and progress toward straighter-leg variations only once the bent-knee version feels smooth and controlled. ## Instructions 1. Lie flat on your back on a mat or the floor with both legs extended straight and your arms resting at your sides, palms facing down. 2. Rest the back of your head on the floor and press your lower back gently toward the ground so there is little to no gap beneath it. 3. Brace your abdominal muscles as if preparing for a light tap to the stomach, and keep your neck relaxed. 4. Exhale and pull both knees up toward your chest, letting the hips curl slightly off the floor at the top of the movement. 5. Pause for a moment with the knees tucked close to the torso, squeezing the lower abs. 6. Inhale as you slowly extend the legs back down, lowering the feet toward the floor with control. 7. Keep the lower back pressed into the floor for the entire descent; if it starts to arch, do not extend the legs as far. 8. Lightly touch the heels to the floor, re-brace, and begin the next repetition. 9. Continue breathing steadily throughout the set and avoid holding your breath. ## Tips & Tricks - A common mistake is dropping the legs quickly on the way down, which turns the exercise into a hip-flexor swing; take two to three seconds to lower instead. - If your heels slam into the floor between reps, hover them just above the ground to keep constant tension on the abs. - Watch that your lower back stays flat against the floor as the legs extend — the moment it lifts, shorten the range rather than letting it arch. - Keep the head and shoulders relaxed on the floor; pulling the chin toward the chest does not increase abdominal work and only strains the neck. - Press your palms lightly into the floor for balance, but avoid pushing down hard, as this can tilt the hips and reduce ab involvement. - Curl the tailbone slightly off the floor at the top of each rep to get a fuller contraction of the lower abs instead of just moving the thighs. - If you feel a pinching sensation at the front of the hips, bend the knees even more or use a slightly smaller range of motion. - Tempo beats reps here — eight slow, controlled knee raises are more productive than twenty fast ones. - To progress, straighten the legs a little more each week as long as your lower back stays in contact with the floor. ## Frequently Asked Questions ### What muscles does the Lying Knee Raise work? The primary muscles are the lower abs, specifically the lower portion of the rectus abdominis, with strong assistance from the hip flexors such as the iliopsoas. The deep core muscles also work to keep your spine stable against the floor. ### Is the Lying Knee Raise good for beginners? Yes, it is one of the most accessible lower-ab exercises because bending the knees shortens the lever and makes the legs easier to control. Beginners can limit how far they extend the legs until their control improves. ### Why does my lower back arch during the Lying Knee Raise? Arching happens when the hip flexors pull on the lumbar spine faster than the abs can stabilize it, usually on the lowering phase. Slow down the descent and stop extending the legs at the point where your back starts to lift off the floor. ### How is the Lying Knee Raise different from a lying leg raise? The knee raise keeps the knees bent, which shortens the lever arm and reduces the load on the abdominals and lower back. The leg raise keeps the legs straight and is considerably harder, so the knee raise is the better starting point. ### Should my hands be flat on the floor or under my hips? Flat at your sides is the standard position and keeps the exercise honest. Sliding the hands under the hips can slightly reduce lower-back discomfort, but avoid pushing down with them, since that takes work away from the abs. ### How many reps of the Lying Knee Raise should I do? Start with two to three sets of ten to fifteen slow repetitions, focusing on control rather than speed. Once you can complete all sets with a flat lower back and no rushing, progress to straighter-leg variations. ### Can I do the Lying Knee Raise every day? Because it uses only your body weight and a moderate range, it recovers quickly and can be performed most days. If your abs feel sore or your lower back feels fatigued, take a rest day as you would with any strength exercise. ### What can I use instead of the Lying Knee Raise if lying on the floor is uncomfortable? A hanging knee raise on a pull-up bar or a captain's chair knee raise trains a similar pattern, though both are harder. A simple reverse crunch on a mat with the knees held more tightly toward the chest is the closest low-load substitute. ### Why do I feel this more in my hip flexors than my abs? The hip flexors naturally do much of the thigh-lifting work in this movement, but if they dominate completely, your abs are probably not braced or your back is arching. Re-press the lower back into the floor before each rep and slow the tempo to shift more of the work to the abdominals.