Exercise guide
Knee Tuck Oblique Crunch
- Beginner
- Compound
- Rep-based
- Waist
The Knee Tuck Oblique Crunch is a dynamic core exercise that emphasizes the obliques and hip flexors through unilateral rotation and flexion. It builds rotational power and lateral stability by isolating one side of the midsection at a time.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Lie flat on your back on a mat with your legs fully extended.
- Place your hands lightly behind your head, keeping your elbows wide.
- Engage your core to press your lower back firmly into the floor.
- Lift your heels 2-3 inches off the ground to create initial tension in the lower abs.
How to do it
- Exhale as you pull one knee toward your chest while simultaneously rotating your torso to bring the opposite elbow toward that knee.
- Squeeze your obliques at the peak of the movement, ensuring your shoulder blade clears the floor.
- Inhale as you slowly return to the starting position with control, keeping your feet hovering above the mat.
- Complete all prescribed repetitions on one side before switching to the other to maintain unilateral tension.
Form checklist
- Keep your lower back pressed into the mat throughout the entire range of motion.
- Rotate from the ribcage rather than just pulling your elbow across your face.
- Avoid pulling on your neck; your hands should only provide light support.
- Maintain a slow and controlled tempo to eliminate momentum.
Pro tips
- Think about bringing your armpit toward the opposite knee to ensure deep trunk rotation and maximum oblique recruitment.
- Keep the non-working leg perfectly straight and hovering to increase the demand on your deep core stabilizers.
Make it harder
- Add a 2-second pause at the point of maximum contraction to intensify the burn.
- Perform the movement with ankle weights to increase the resistance on the hip flexors and lower abdominals.
Frequently asked
- What muscles does the knee tuck oblique crunch work?
- The knee tuck oblique crunch primarily targets the abs and obliques, and also works the hip flexors as secondary muscles.
- What equipment do you need for the knee tuck oblique crunch?
- The knee tuck oblique crunch requires no equipment — just your body weight.
- Is the knee tuck oblique crunch good for beginners?
- Yes. The knee tuck oblique crunch is a beginner-friendly movement and a strong foundation to build on.