Tuck Crunch
The tuck crunch curls your upper body and your knees toward each other at the same time, meeting somewhere in the middle. Because both ends of your body move at once, it asks more of your abdominals through a longer range than a standard crunch, while staying simple enough to do anywhere with just your bodyweight.
Why it works
Your abdominals connect your ribcage to your pelvis, so they shorten whenever either end moves toward the other. A standard crunch only moves the ribcage; the tuck crunch moves both the ribcage and the pelvis toward the middle at the same time, which means the abdominals have to shorten from both directions in a single rep. That double-ended curl is why this version feels noticeably harder than a basic crunch even without added weight. Coordinating both ends also trains something a single-ended crunch doesn't: the timing to bring your upper and lower body together smoothly, rather than letting one end do most of the work while the other just comes along for the ride.
Set up
- Lie on your back with your knees bent and feet flat, or hover your heels just off the floor for a harder start.
- Rest your hands lightly behind your head or crossed over your chest.
- Brace your core gently before the first rep.
How to do it
- Curl your shoulders up off the floor while simultaneously pulling your knees in toward your chest.
- Bring your upper body and your knees toward each other until they nearly meet.
- Pause briefly at the top and feel the contraction through your entire abdomen.
- Lower your shoulders and extend your legs back out together, under control.
- Stop just before your shoulder blades touch the floor and your legs straighten fully, then begin the next rep.
- Keep the motion smooth on both ends instead of letting momentum fling your legs or torso.
Form cues
- Both ends curl in together.
- Meet in the middle, don't just fold your hips.
- Exhale hard at the top.
- Lower both ends at the same controlled speed.
Breathing: Exhale as you curl your shoulders and knees together, inhale as you extend back out.
Common mistakes
Using the arms to yank the head and neck forward instead of letting the abs do the curling.
Fix: Keep your hands light against your head and lead the movement with your ribcage, not your arms.
Letting the legs swing with momentum rather than pulling the knees in with control.
Fix: Slow the tempo down and pull your knees toward your chest deliberately rather than kicking them in.
Only moving one end of the body, like curling the shoulders while the legs stay mostly still.
Fix: Time both movements to arrive at the middle together; that's what makes this exercise harder than a regular crunch.
Letting the lower back arch as the legs extend back out.
Fix: Keep your lower back gently pressed toward the floor through the entire rep, especially as you straighten your legs.
Rushing through reps to get a higher count, which usually shortens the range at both ends.
Fix: Slow down and aim for your shoulders and knees to actually travel close to meeting each rep, rather than counting shallow half-reps.
How to program it
- Two or three sets of 12 to 15 reps is a solid starting point for most people.
- Since this is a bodyweight isolation move with low systemic fatigue, it fits well at the end of almost any session, two to four times a week.
- Progress by slowing the tempo on the way down before adding more reps or moving to a resisted ab exercise.
- Pair it with a lower-back or hip-flexor stretch afterward if you feel tightness build up from the repeated hip flexion.
- If you're new to coordinating both ends at once, practice the upper-body curl and the knee tuck as separate movements first, then combine them once each half feels controlled on its own.
Safety notes
- If your lower back lifts or arches during the rep, shorten the range until your core control catches up.
- Stop if you feel strain in your neck rather than your abs; rest your head lighter in your hands and let the abdominals lead.
Exercise profile
- Force
- Pull
- Mechanics
- Isolation
- Category
- Strength
Frequently asked questions
How many tuck crunches should I do?
Two or three sets of 12 to 15 reps works well as a starting point, done two to four times a week.
What's the difference between a tuck crunch and a regular crunch?
A regular crunch only curls the upper body. A tuck crunch curls the shoulders and pulls the knees in at the same time, working the abdominals from both ends in one rep.
How do I make the tuck crunch harder?
Slow down the lowering phase first, then try holding a small weight against your chest or moving to a resisted move like the cable crunch.
Why does my neck hurt doing tuck crunches?
Usually the hands are pulling the head forward to help the torso curl. Rest your fingertips lightly behind your head instead and let your abdominals lead the lift.
Is the tuck crunch safe for a sensitive lower back?
Keep the range controlled and your lower back pressed gently toward the floor throughout. If it still feels uncomfortable, start with the regular crunch and build toward the tuck version over time.