Appears in642 Workouts*

Knee in & Out Crunch

Strengthen your core with the Knee In & Out Crunch! A challenging exercise for toned abs and improved stability.

The Knee in & Out Crunch is a compound exercise that mainly works the core, with help from the lower back. No equipment needed: it uses just your bodyweight.

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Knee in & Out Crunch Muscles Worked

Primary

Abdominals (rectus abdominis); Obliques

Secondary

Deep Core (transverse abdominis); Lower Back (quadratus lumborum)

How to do the Knee in & Out Crunch

Knee-In-and-Out Crunch

Positioning

  1. Start by lying flat on your back on a comfortable surface, such as a yoga mat.

  2. Extend your arms straight above your head with palms facing each other.

  3. Raise your legs off the ground, bending at the knees to form a 90-degree angle, with your feet together. Your thighs should be perpendicular to the floor.

Movement

  1. Inhale and engage your core.

  2. As you exhale, pull your knees towards your chest while simultaneously raising your upper body off the ground. Your arms should reach towards your feet in a hugging motion.

  3. Hold this position for a brief moment, feeling the contraction in your abdominal muscles.

  4. Inhale as you slowly lower your upper body back to the ground and extend your legs away from you, keeping them just above the floor without touching it.

  5. Repeat the movement by exhaling to pull your knees back in towards your chest and inhaling to extend them out again.

  6. Aim for 10-15 repetitions, maintaining control throughout the movement.

Tips

  • Keep your back flat against the mat during the exercise.

  • Focus on using your core to perform the movement rather than swinging your legs.

  • Ensure your movements are slow and controlled to maximize effectiveness and minimize injury risk.

Knee in & Out Crunch FAQs

What muscles does the Knee in & Out Crunch work?

The Knee in & Out Crunch mainly works the core, with help from the lower back. The main muscles are the rectus abdominis and obliques.

What equipment do you need for the Knee in & Out Crunch?

None. The Knee in & Out Crunch is a bodyweight exercise, so you can do it anywhere.

Is the Knee in & Out Crunch a compound exercise?

Yes. It's a compound movement, meaning it trains several muscle groups at once rather than isolating one.

What are some Knee in & Out Crunch variations and alternatives?

Similar exercises include the 90-Degree Single Knee Crunch, Bent-Knee Crunch Abduction with Arm Through, Groin Crunch and Knee Tap Crunch.

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