Oblique Crunches - On The Floor
This floor variation of the oblique crunch skips the twist and instead has you reach one hand straight down toward your heel while your shoulders lift, training the obliques through side bending rather than rotation. It's a beginner bodyweight move, done flat on the floor with no equipment, and pairs naturally with rotational ab work for a fuller side-core routine.
Why it works
The obliques don't just rotate the torso, they also bend it sideways, and a straight reach toward the heel isolates that side-bending function without any twist mixed in. Because the movement stays in one plane, it's easier to feel exactly which side is working, which makes it a useful teaching tool for beginners still learning to control their core rather than just their arms and hips.
Set up
- Lie flat on your back with your knees bent and feet flat on the floor, hip-width apart.
- Rest your arms straight down at your sides, palms facing your legs.
- Brace your core gently so your lower back doesn't arch off the floor.
How to do it
- Lift your shoulder blades a few inches off the floor, curling straight up rather than to one side.
- As you curl, slide one hand along the floor toward the heel on the same side.
- Reach as far as your range allows without twisting your ribcage or lifting your hips.
- Hold the top position for a brief squeeze on that side of your waist.
- Lower back down with control until your shoulder blades touch the floor.
- Repeat the reach toward the other side, alternating for the set.
Form cues
- Reach straight down the side, don't rotate the ribcage.
- Keep both hips glued to the floor the whole time.
- Move slow enough to feel the side of your waist working.
- Small, controlled lift, not a big sit-up.
Breathing: Exhale as you curl and reach toward your heel, inhale as you lower back down.
Common mistakes
Twisting the ribcage instead of reaching straight down the side.
Fix: Keep your chest facing the ceiling the entire time; only your reaching arm and the side of your torso should move.
Letting one hip lift off the floor to help the reach.
Fix: Keep both hips pressed down and shorten the reach if that's what it takes to keep them still.
Using the free arm to push off the floor for momentum.
Fix: Keep the resting arm relaxed at your side and let the working side do all the lifting.
How to program it
- Start with 2 to 3 sets of 10 to 12 reps per side, since it's a small, low-fatigue isolation move.
- It suits the end of a workout or a short standalone core session, since it needs no warm-up load.
- Once the reach feels easy at full range, slow the tempo instead of adding weight, since a controlled lateral flexion is harder to fake than a fast one.
Safety notes
- If you feel the reach in your neck rather than your side, shorten the range and focus on the curl coming from your ribs.
- Stop and reset if your lower back arches instead of staying gently pressed down.
Exercise profile
- Force
- Pull
- Mechanics
- Isolation
- Category
- Strength
Frequently asked questions
How is this different from a regular oblique crunch?
This version reaches straight toward your heel with no twist, training side bending. The classic oblique crunch adds rotation, turning your ribcage toward the opposite knee.
How many reps of floor oblique crunches should I do?
10 to 12 reps per side for 2 to 3 sets is a reasonable starting point. Slow the tempo down before adding any load.
Can beginners do oblique crunches on the floor?
Yes, it's one of the more approachable oblique exercises since there's no rotation to coordinate, just a straight reach down one side.
Why can't I feel this in my obliques?
You may be twisting instead of bending straight to the side, or reaching too far and using your hip to help. Keep your chest facing up and shorten the reach until you feel the side of your waist working.