Oblique Crunches Floor
- Target muscle
- Obliques
- Synergist muscles
- Rectus Abdominis
- Equipment
- Body weight
- Body part
- Waist
- Type
- Strength
Oblique Crunches Floor is a bodyweight waist exercise that targets the obliques, with the rectus abdominis assisting as a synergist. You lie on your back with both knees dropped to one side, which pre-stretches the obliques on the top side of your waist and makes them drive a short, diagonal crunch. It is a simple way to train side-bending and anti-rotation strength at home, with no equipment needed.
How to do the Oblique Crunches Floor
- 1Lie on your back with your knees bent, feet flat on the floor about hip-width apart.
- 2Rest your fingertips lightly behind your head with your elbows wide — do not interlace your fingers or grip your neck.
- 3Let both knees fall to one side, for example to the left, and keep both shoulder blades on the floor so your torso stays square to the ceiling.
- 4Brace your abs and exhale as you curl your head, shoulders, and upper back off the floor, driving up and slightly toward your lowered knees.
- 5Stop once your shoulder blades clear the floor and squeeze the obliques on the top side of your waist for one second.
- 6Inhale as you lower your upper back to the floor under control, keeping tension on the abs rather than resting between reps.
- 7Complete all reps on that side, then drop your knees to the opposite side and repeat for the same number of reps.
Form tips
- Lead with your shoulder, not your elbow — the shoulder cue puts the work in the obliques and keeps your neck out of the movement.
- Keep your lower back pressed into the floor for the whole set so the crunch stays short and the lumbar spine stays neutral.
- Treat range of motion as small and deliberate: a few inches of shoulder-blade lift with a hard contraction beats swinging high.
- Exhale forcefully on the way up — the forced exhale tightens the abdominal wall and deepens the oblique contraction.
- If the set gets easy past 20 reps, slow the tempo to a three-second lower rather than adding speed.
Common mistakes
- Pulling the head forward with the hands, which loads the cervical spine and lets the neck flexors do work the obliques should be doing.
- Swinging the torso up with momentum, which removes tension from the obliques and can strain the abdominal wall.
- Curling straight up toward the ceiling instead of angling toward the lowered knees, which turns the movement into a standard crunch and shifts the load to the rectus abdominis.
- Letting the shoulder on the top side peel off the floor and rotate as the knees drop, which unloads the target obliques and can leave the lower back unsupported.
- Holding the breath through the rep, which spikes intra-abdominal pressure and costs you the bracing you get from a controlled exhale.
Frequently asked questions
What muscles do oblique crunches floor work?
The target is the obliques — the muscles along the sides of your waist. The rectus abdominis assists as a synergist on every rep, since the movement is still a trunk curl.
How is this different from a standard crunch?
In a standard crunch your knees point at the ceiling and you curl straight up, loading the rectus abdominis. Here your knees drop to one side and you curl diagonally, which shifts the work onto the obliques on the top side of your waist.
Should I feel this in my neck?
No. Neck strain means your hands are pulling your head. Rest the fingertips behind your head without gripping, keep the elbows wide, and start each rep from the shoulder so the obliques initiate the curl.
Are oblique crunches floor good for beginners?
Yes. There is no load, no equipment, and a short range of motion, so it is one of the safest entry points to oblique training. Start with a set you can control and add reps before you add speed.
How many sets and reps should I do per side?
Because the exercise is bodyweight only, 2–3 sets of 12–20 reps per side works well. Finish every rep on one side before switching so the obliques stay under continuous tension.
