Pulse Ups: The Lower-Ab Exercise Explained

Pulse ups are a bodyweight core exercise where you lie on your back with legs raised to 90 degrees and pulse your hips an inch or two off the floor to bias the lower rectus abdominis. Some coaches call them “heels to the heavens.”

They are popular because they need zero equipment, work in any size apartment, and target the stubborn lower-ab region most people struggle to feel.

Below, we cover the evidence on lower-ab activation, correct form, the mistakes that ruin the movement and who should skip them entirely.

What Muscles Pulse Ups Actually Work

The rectus abdominis is anatomically one muscle. It runs from your pubic bone up to the sternum and lower ribs, split into visible segments by tendinous inscriptions and innervated by multiple segmental nerves.

True upper-versus-lower isolation is not possible, which is why lower abs gets dismissed as marketing.

But regional preferential activation is real, and pulse ups bias the lower fibers. The evidence has two chapters worth knowing.

The 2003 EMG pilot study, they tested six abdominal exercises including a reverse curl-up and found no significant differences between upper and lower rectus abdominis activation. That result gets quoted constantly to argue lower-ab targeting is a myth.

The newer and better-powered chapter is a 2023 ultrasound study. They used both EMG and diagnostic ultrasound on 15 participants, and crunches produced 36.39% greater mean rectus abdominis thickness change than leg raises (p<0.01). Their conclusion was blunt: “muscle recruitment seems to be biased closer to the load.”

Exercises that move the pelvis toward the ribcage, like pulse ups and reverse crunches, recruit the inferior fibers more. Exercises that move the ribcage toward the pelvis, like crunches, recruit the superior fibers more.

Secondary movers during pulse ups include the obliques and transverse abdominis, with the hip flexors (iliopsoas) and glutes pitching in.

The erector spinae stabilize the lumbar spine. The lower-ab bias claim is a legitimate training target, as long as your form puts the load where it is supposed to go.

Pulse Ups Benefits

If crunches are your only ab move, you are leaving the rest of this list on the table.

Biased lower-ab

Leg-raise-family movements preferentially recruit inferior rectus abdominis fibers, which is what most lifters are chasing when they say “lower abs.”

Lower spinal compression than crunches and sit-ups

Your lumbar spine stays glued to the mat during pulse ups. That is kinder on disc tissue than repeated spinal flexion, especially if you already get mild lumbar irritation from heavy sit-up variations.

Carryover to squats and deadlifts

The posterior pelvic tilt you train during pulse ups is the same bracing pattern that keeps your ribs down and your spine neutral under a barbell.

Pair them with plank variations to round out your anti-extension and anti-rotation work.

No equipment, minimal space

A mat and six feet of floor is all you need. They scale cleanly from dead bug up to hanging leg raise, which makes them travel-friendly and home-gym-friendly.

Cleanest lower-ab finisher available

Small range of motion, high intensity, and they pair well at the end of a core or lower-body session without taxing your grip or back.

How to Do Pulse Ups With Proper Form

Most of the value of pulse ups lives in one detail that 20-second YouTube tutorials skip. Your tailbone has to peel off the mat on every rep, or the movement turns into a hip-flexor exercise with extra steps.

On the legs-bent-versus-straight question, straight legs are the default intermediate standard.

Bent knees are a valid regression for beginners or anyone with lower-back sensitivity, not a separate exercise.

Here is how to do pulse ups:

• Lie flat on a mat with arms at your sides, or tuck your hands palms-down under your tailbone for lumbar support.
• Raise both legs perpendicular to the floor. Keep a soft bend in the knee if locking out feels harsh.
• Draw your navel toward your spine and press your lower back firmly into the mat. This is the posterior pelvic tilt starting position.
• Contract your abs and glutes to lift your hips and feet 4 to 8 inches toward the ceiling in a small, controlled pulse. Hold 1 second at the top.
• Lower your hips back to just above the floor under control. Do not fully relax between reps.
• Exhale on the upward pulse, inhale as you lower. Aim for 8 to 15 reps per set across 3 sets with a controlled tempo.

One cue to lock in: if your tailbone is not peeling off the mat, you are only training hip flexors.

Common Pulse Up Mistakes (And How to Fix Them)

If pulse ups burn in your hip flexors instead of your abs, you are not broken. You are making the same mistake most people do.

Mistake 1: Hip flexor dominance

You feel the burn in the front of your hips instead of your abs.

Fix: your tailbone must actually peel off the mat each rep, and you need to curl your pelvis toward your ribcage instead of swinging your legs.

Mistake 2: Lower back arches off the floor

This stresses the lumbar spine and shifts load away from the abs.

Fix: actively press your lower back into the mat before every rep, hold the posterior pelvic tilt throughout, and regress to the bent-knee version if you cannot keep it pinned down.

Mistake 3: Using momentum and swinging

The pulse looks fast, feels easy, and does almost nothing for your abs.

Fix: count 2 seconds up and 2 seconds down. Every rep starts from the abs contracting, not the legs throwing themselves upward.

Mistake 4: Legs drifting forward past 90 degrees

When your feet tip away from vertical, the load shifts onto your hip flexors and the tension on your abs drops.

Fix: keep your legs pointed straight at the ceiling the whole set, and if you cannot hold that position, end the set.

Pulse Up Variations, Progressions, and Who Should Skip Them

Pulse ups are either too easy to matter or too risky to do safely, depending on who is doing them. The fix is picking the right version of the movement for your body.

Progression Ladder

• Dead bug (regression) – Builds posterior pelvic tilt with almost no spinal load. Start here if you cannot keep your lower back pinned down.
• Bent-knee pulse ups (beginner) – Knees bent at 90 degrees, feet off the floor. Same pulse, shorter lever arm.
• Straight-leg pulse ups (intermediate standard) – The default version above.
• Slow-eccentric pulse ups (intermediate+). Take 3 to 4 seconds to lower each rep to maximize time under tension.
• Ankle-weighted pulse ups (advanced) – Add 2 to 5 pounds for progressive overload.
• Decline bench pulse ups (advanced) – Gravity works harder against you at a 30-degree decline.
• Hanging knee raise / leg raise (elite) – Per Scott Herman, knees must travel past 90 degrees to the chest to bias the lower abs. Stopping at 90 is hip-flexor territory.

Who Should Skip or Modify

• Diastasis recti. Both-leg movements raise intra-abdominal pressure and can widen postpartum abdominal separation. Skip standard pulse ups and see a pelvic floor physiotherapist. Safer alternatives include single-leg lowering with a strong exhale, heel slides, and dead bug.
• Disc issues or acute lower back pain. Straight-leg supine movements load the lumbar spine. Regress to the bent-knee version, or swap in dead bug until a physio clears you.
• Pregnancy beyond the first trimester. Supine double-leg exercises are generally avoided in the second and third trimesters. Pick pregnancy-safe core alternatives your provider approves.
• Acute neck strain. Keep your head neutral on the mat. If you feel the lift in your neck, the movement is coming from your upper body instead of your hips.

FAQs

What’s the difference between pulse ups and reverse crunches?

Pulse ups use a small, repetitive pulsing motion at the top of hip flexion. Reverse crunches use a full range of motion curl where the lower back rolls completely off the mat.

Reverse crunches give you more eccentric stretch and a fuller muscular stimulus per rep. Pulse ups are simpler to learn, pair well with higher-rep endurance sets, and are often easier on a fatigued lower back.

Why do I feel pulse ups in my hip flexors, not my abs?

You are hinging at the hips without lifting your lower back off the floor. The fix is mechanical, not motivational.

Place your hands under your tailbone so you can feel when it lifts, actively press your lower back into the mat, and initiate every rep by curling your pelvis toward your ribcage instead of swinging your legs up. If the tailbone does not peel off the mat, the abs are not doing the primary work.

Should I keep my legs straight or bent during pulse ups?

Both variations are valid. Straight legs create a longer lever arm and load the abs and hip flexors more, which is the intermediate-to-advanced standard.

Bent knees shorten the lever arm and reduce lower-back stress, which makes them the better starting point for beginners or anyone with lumbar sensitivity. The posterior pelvic tilt mechanic is the same either way.

Are pulse ups safe with lower back pain?

Not recommended without modification. Straight-leg pulse ups load the lumbar spine and hip flexors, which can aggravate existing low-back pain.

Use the bent-knee version, tuck your hands under your tailbone for support, or swap in dead bug, which trains the same posterior pelvic tilt pattern with almost no spinal load.

Anyone with disc issues, sciatica, or acute pain should see a physiotherapist before returning to the straight-leg version.

Will pulse ups alone give me lower ab definition?

No. Visible lower abs require two things: muscle development, which pulse ups can absolutely contribute to, and low enough body fat to see the muscle underneath, which pulse ups have zero influence on.

Spot fat reduction does not work. Build the muscle with pulse ups and similar movements, and reveal it with an overall caloric deficit and full-body training.

Bottom Line

Pulse ups are a legitimate lower-ab-biased exercise with real evidence behind the bias claim, not marketing. Form decides whether they work.

Your tailbone has to peel off the mat, your lower back has to stay glued down, and your tempo has to stay controlled.

Start with 3 sets of 10 to 15 straight-leg pulse ups, 2 to 3 times per week, and progress through slow eccentrics or ankle weights once every set is clean. Skip or heavily modify if you have diastasis recti, disc issues, or acute lower back pain.

Pulse ups are not magic, but done right, they are one of the cleanest lower-ab moves you can do without equipment.