Seated Alternate Crunch

Muscles worked

Setup

1. Sit on the edge of a flat bench with your feet flat on the floor and knees bent at 90 degrees.
2. Lean your torso back slightly to a 45-degree angle, engaging your core to maintain a neutral spine.
3. Place your fingertips lightly behind your ears with your elbows flared out wide.
4. Ensure your weight is balanced on your sit-bones to allow for fluid leg movement.

How to do it

1. Exhale and lift your right knee toward your chest while rotating your torso to bring your left elbow toward the rising knee.
2. Inhale as you slowly lower your leg and rotate your torso back to the starting centered position.
3. Repeat the movement on the opposite side, lifting your left knee and rotating your right elbow across your body.
4. Maintain a controlled 2-1-2 tempo (2 seconds up, 1 second squeeze, 2 seconds down) to avoid using momentum.

Form checklist

• Rotate from the waist and ribcage rather than just pulling your elbow forward.
• Keep your chest open and avoid pulling on your head or neck with your hands.
• Ensure your stationary foot remains planted firmly on the floor for balance.
• Maintain a slight lean back throughout the entire set to keep constant tension on the abs.

Pro tips

• Focus on the mind-muscle connection by visualizing your ribcage moving toward your opposite hip bone.
• Pause for a split second at the peak of the contraction to maximize oblique and quadriceps engagement.

Make it harder

• Keep both feet hovering off the floor for the duration of the set to increase the demand on the lower abs and hip flexors.
• Hold a small medicine ball against your chest to add resistance to the rotational component.

Frequently asked

What muscles does the seated alternate crunch work?

The seated alternate crunch primarily targets the abs and obliques, and also works the erector spinae as secondary muscles.

What equipment do you need for the seated alternate crunch?

The seated alternate crunch requires no equipment — just your body weight.

Is the seated alternate crunch good for beginners?

Yes. The seated alternate crunch is a beginner-friendly movement and a strong foundation to build on.

Related exercises

• 3/4 Sit-UpBeginner · abs and obliques
• 45 Degree Bicycle Twisting CrunchIntermediate · abs and obliques
• 45 Degree Lean Back Alternate Knee RaiseBeginner · abs and obliques
• 45 Degrees Arms PlankIntermediate · abs, deltoids, obliques, and pectorals