Knee In And Out Crunch
Knee In And Out Crunch Exercise Description
The Knee In and Out Crunch is a bodyweight floor exercise that blends trunk flexion with coordinated hip flexion to challenge the anterior core. It primarily targets the rectus abdominis while the hip flexors assist and the obliques stabilize the pelvis and ribcage. By controlling the legs and torso as a unit, you train lumbopelvic control and resist excessive lumbar extension during dynamic movement. The movement alternates between extending the legs while leaning the torso back slightly, then drawing the knees in while flexing the trunk, emphasizing smooth, controlled ranges over momentum. Proper positioning—ribs down, slight posterior pelvic tilt, shoulders packed, and a neutral neck—helps direct the workload to the abdominal wall and reduces compensations from the lower back and shoulders.
- Muscle Groups: Abs, Core, Waist
- Target Muscles: Rectus Abdominis
- Assisting Muscles: Iliacus, Psoas Major, Rectus Femoris
- Stabilizing Muscles: External Obliques, Internal Obliques, Transversus Abdominis
- Body Area: Upper Body
- Body Parts: Core, Torso
- Body Surface: Front
- Body Symmetry: Bilateral
- Equipment: Bodyweight
- Exercise Patterns: Other
- Exercise Type: Strength
- Functional Grouping: Trunk Flexors
- Joint Involvement: Multi-joint
- Muscle Location: Stomach
- Movement Direction: Other
- Muscle Position: Anterior
- Gender: Male
How To Do The Knee In And Out Crunch Exercise
‘- Sit on the floor, knees bent, feet together, hands on the floor slightly behind your hips, fingers forward.
– Pack your shoulders, brace your abdomen, and gently draw ribs toward pelvis to create a slight posterior pelvic tilt.
– Lift your feet to hover; keep chest open and neck neutral.
– Inhale as you extend both legs forward while leaning your torso back slightly as one unit; avoid arching your lower back.
– Exhale as you pull your knees toward your chest, allowing a controlled trunk curl; bring thighs and ribcage toward each other.
– Keep movement smooth; avoid bouncing, shrugging the shoulders, or yanking with the arms.
– Set feet down briefly to reset if control or alignment is lost.
Knee In And Out Crunch Tips
‘- Place your hands on the floor slightly behind your hips with fingers pointing forward to set your base.
– Pack your shoulders and brace your abdomen before you start moving.
– Gently draw your ribs toward your pelvis to create a slight posterior pelvic tilt and keep the ribs down.
– Lift your feet to hover while keeping your chest open and neck neutral.
– Inhale as you extend both legs forward and lean your torso back slightly as one unit, avoiding any arch in your lower back.
– Exhale as you pull your knees toward your chest, allowing a controlled trunk curl so your thighs and ribcage move toward each other.
– Keep each rep smooth and controlled; avoid bouncing, shrugging the shoulders, or yanking with the arms.
– If you lose control or alignment, briefly set your feet down to reset before continuing.
Knee In And Out Crunch Beginner Introduction
The Knee In and Out Crunch is a bodyweight ab exercise performed on the floor that links torso curling with hip movement to challenge the front of the core. The main work falls on the abs, with the hip flexors helping to lift and lower the legs while the side abs assist in steadying the pelvis and ribcage. A major theme is teaching the hips and lower spine to move as a solid unit, rather than letting the lower back over-arch as the legs travel. Each repetition alternates between a more lengthened position, with legs stretched forward and the torso reclined slightly, and a compact position, with knees drawn in and the trunk curled. The rhythm emphasizes steady, deliberate motion rather than swinging or jerking, so tension stays on the midsection. Attention to rib, pelvis, shoulder, and neck alignment channels effort into the abdominal wall and limits help from the lower back and shoulders.
Because the exercise relies solely on bodyweight and a small amount of floor space, it fits easily into home or gym ab training. The coordinated leg and torso action builds awareness of how the core, hips, and breathing interact during multi-joint movement.