Exercise guide
Oblique Crunches Floor
- Beginner
- Isolation
- Rep-based
- Waist
This exercise isolates the internal and external obliques through lateral spinal flexion, helping to define the waistline and improve rotational core stability.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Lie flat on your back with your knees bent and feet flat on the floor.
- Lower both knees to the right side until they rest on the floor, keeping your upper back and shoulders flat against the ground.
- Place your fingertips lightly behind your ears or cross your arms over your chest.
How to do it
- Exhale and contract your obliques to lift your shoulder blades off the floor, crunching straight up toward the ceiling.
- Hold the peak contraction for one second, focusing on the squeeze in the side of your waist.
- Inhale as you slowly lower your shoulders back to the floor with a controlled 2-second tempo.
- Complete the full set on one side before switching your knees to the opposite side.
Form checklist
- Keep your lower back in contact with the floor throughout the movement.
- Avoid pulling on your head or neck; use your core to initiate the lift.
- Ensure your knees stay stacked and resting on the floor to maintain the torso twist.
- Keep your chin tucked slightly to maintain a neutral cervical spine.
Pro tips
- Visualize bringing your bottom rib toward your hip bone to maximize the shortening of the oblique muscles.
- Press the small of your back into the floor as you lift to ensure the rectus abdominis assists in the stabilization.
Make it harder
- Lift your feet off the floor into a 'tabletop' position while keeping the knees rotated to increase the load on the lower abs.
- Extend your top arm straight toward your heels to increase the lever length and resistance.
Frequently asked
- What muscles does the oblique crunches floor work?
- The oblique crunches floor primarily targets the abs and obliques, and also works the erector spinae as secondary muscles.
- What equipment do you need for the oblique crunches floor?
- The oblique crunches floor requires no equipment — just your body weight.
- Is the oblique crunches floor good for beginners?
- Yes. The oblique crunches floor is a beginner-friendly movement and a strong foundation to build on.